Management of Shade trees in the tea gardens of Bangladesh with special reference to the Rasidpur...

PROJECT PAPER

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PROJECT PAPER

COURSE NO-424

MANAGEMENT OF SHADE TREES IN THE TEA GARDENS OF

BANGLADESH WITH SPECIAL REFERENCE TO THE

RASIDPUR AND KAMAICHORA TEA ESTATE

A dissertation presented as a requirement for the degree of 4-year professional Bachelor of Science (Hons) in Forestry,

Institute of Forestry & Environmental Sciences, University of Chittagong Chittagong, Bangladesh

Supervised By

Dr. Mohammed Shafiul Alam

Associate Professor

Institute of Forestry and

Environmental Sciences

University of Chittagong

Submitted by

Mohammad Redowan

Exam Roll No: 97/22

Reg. No: 138

Session: 1996-97




CERTIFICATION

This is to certify that the author Mohommad Redowan bearing Exam Roll. 97/22, Reg. No.

138, Session: 1996-97 has prepared this Project Paper “Management of Shade trees in the tea gardens

of Bangladesh with special reference to the Rasidpur and Kamaichora Tea Estate” under my guidance

and supervision. I do hereby approve the style and content of this Project paper. This is for the partial

fulfillment of 4-year Professional Bachelor of Science (Hons) in Forestry degree of the Institute of

Forestry and Environmental Sciences, University of Chittagong, Chittagong, Bangladesh.

Dr. Mahammed Shafiul Alam

Associate Professor




Chittagong, Bangladesh.

DECLARATION

I would like to take the opportunity to declare that this Project Paper has been compiled

by me to submit it to the Institute of Forestry and Environmental Sciences for the partial

fulfillment of the requirements for the degree of B. Sc. (Hon’s.) in Forestry. This Project

Paper has not been submitted in any application in the past for the fulfillment of any degree.

The literature review and field works mentioned in this paper were absolutely executed by me

unless otherwise stated.

Mohammad Redowan

September, 2003

DEDICATED TO

MY LATE FATHER

MR. MOHAMMAD SIRAJUL ISLAM

WHO LEFT US VERY EARLY

AT THE AGE OF 52

IN MAY 1999

TABLE OF CONTENTS

TABLE OF CONTENTS .......................................................................................................... I

LIST OF TABLES .................................................................................................................. III

LIST OF FIGURES ................................................................................................................ III

ACKNOWLEDGEMENT .................................................................................................. IV

ABSTRACT ............................................................................................................................ V

1. INTRODUCTION .............................................................................................................. 1

2. OBJECTIVES ..................................................................................................................... 4

3. METHODOLOGY ............................................................................................................. 5

4. General description of rasidpur and kamaichora tea estate ................................................ 6

4.1. Location and area ......................................................................................................... 6

4.2. Tea Climate ................................................................................................................. 6

4.3. Tea soil ......................................................................................................................... 6

4.3.1. Ideal condition for tea soil .................................................................................... 6

4.4. Soil and topographic condition .................................................................................... 7

4.4.1. Soil texture ............................................................................................................ 7

4.4.2. Soil structure ......................................................................................................... 7

4.5. Topographic condition of Rasidpur and Kamaichora tea estates ................................ 7

5. SHADE TREE .................................................................................................................... 8

5.1. Types of shade trees ..................................................................................................... 8

5.1.1. Permanent shade trees: ......................................................................................... 9

5.1.2. Temporary shade trees .......................................................................................... 9

6. SOIL AND CLIMATIC REQUIREMENTS OF SOME SHADE TREE SPECIES ....... 10

6.1. Acacia auriculiformis A. Cunn. ex Benth .................................................................. 10

6.2. Acacia mangium Willd .............................................................................................. 10

6.3. Albizia falcataria (L.) Fosberg ................................................................................... 11

6.4. Albizia lebbek (L.) Benth. ......................................................................................... 12

6.5. Cajanus cajan (L.) Millsp. .......................................................................................... 12

6.6. Dalbergia sissoo Roxb. .............................................................................................. 13

6.7. Gliricidia sepium (Jacq.) Steud. ................................................................................. 13

6.8. Leucaena leucocephala .............................................................................................. 14

6.9. Matching Species with Site ........................................................................................ 15

7. Growth performance of shade trees .................................................................................. 15

8. Silviculture of shade trees ................................................................................................. 17

8.1. Mixture of shade tree species ..................................................................................... 19

II

8.2. Spacing of shade tree ................................................................................................. 20

8.3. Lay Out Of Tea / Shade / Green Crop ....................................................................... 21

8.4. Planting of shade trees ............................................................................................... 23

9. Propagation of shade trees ................................................................................................ 24

10. Establishment of shade .................................................................................................. 25

11. Effect of shade per se .................................................................................................... 26

12. Shade trees and litterfall ................................................................................................ 26

13. Shade and light intensity ................................................................................................ 28

14. Shade and tea leaf temperature ...................................................................................... 28

15. Effect of shade trees on light climate ............................................................................ 29

16. Shade and partition of growth ....................................................................................... 30

17. Shade effect on quality of made tea ............................................................................... 31

18. Current perspective ........................................................................................................ 31

19. Management of Shade Trees ......................................................................................... 33

19.1. Lopping and Uprooting of Shade Trees ................................................................. 34

19.2. Uprooting................................................................................................................ 36

20. The Bad Effects of Shade .............................................................................................. 36

20.1. Competition between shade trees and tea bushes .................................................. 37

21. Role of shade trees in reducing wind damage ............................................................... 37

21.1. Planting materials and wind damage ...................................................................... 38

21.2. Shade trees as shelterbelt ........................................................................................ 39

22. Importance of shade trees at a glance ............................................................................ 41

23. Uses of Shade trees ........................................................................................................ 41

24. A grief description of two important shade trees used in Bangladesh tea estates ......... 44

24.1. Gliricidia Sepium As A Shade Tree ....................................................................... 44

25. Leucaenas as shade trees ............................................................................................... 46

25.1. Some information about Ipil-ipil (Leucaena leucocephala), a common leucaena,

which is used as shade tree in the tea estate is given here; ................................................... 48

26. Influence of Shade on the Incidence of Pests in Tea Plantation in Bangladesh ............ 49

27. Diseases of Shade Trees ................................................................................................ 50

27.1. Leaf diseases .......................................................................................................... 50

27.2. Stem diseases .......................................................................................................... 53

27.3. Root diseases .......................................................................................................... 57

28. Catalogue of Pests on Shade Trees and Ancillary Crops .............................................. 61

29. Problems of shade tree management in Bangladesh ..................................................... 67

30. RECOMMENDATION ................................................................................................. 69

31. CONCLUSION .............................................................................................................. 71

REFERENCES ........................................................................................................................ 72

III

LIST OF TABLES

Table 1 Bangladesh tea research institute test the soil sample of Rasidpur tea estate and give

the following information. ............................................................................................... 8

Table 2 Showing the growth performance of A. chinensis and A. odoratissimaxin in

Kamaichora and Rasidpur tea estates respectively ........................................................ 16

Table 3 Spacing of shade trees used in the Rasidpur and Kamaichora tea estates depending on

location (in m.) ............................................................................................................... 21

Table 4. Pests of shade trees and ancillary crops................................................................... 61

LIST OF FIGURES

Figure 1: High and low shade of Grevillea and Dodaps in tea plantation ................................ 25

Figure 2: Mixture of various shade trees (Ipil-ipil, Shada koroi, Chakua koroi) used at

Rasidpur Tea Estate .......................................................................................................... 33

Figure 3: Wind damaged tea bush ............................................................................................ 39

Figure 5: Packaging of tea in the tea chests is going on .......................................................... 43

Figure 6: Gliricidia sepium which is used as temporary shade tree in the tea plantation ........ 44

Figure 7: Acacia auriculiformis used as shade tree at Rasidpur Tea Estate ............................. 69

IV

ACKNOWLEDGEMENT

I express my deepest sense of gratitude and indebt ness to my respected teacher and

supervisor of this project paper, Dr. MOHAMMED SHAFIUL ALAM, Associated Professor,

Institute of Forestry and Environmental Sciences, University of Chittagong, for his perfect

supervision, proper guidance, constructive criticism, inspiration, and affection during the

preparation of this project paper. Without his kind supervision and encouragement I could not

come up with this project paper. I am grateful to Mrs. Jarin Akhter, Lecturer, Institute of Forestry

and Environmental Sciences, University of Chittagong, for providing the book ‘Tea Environments

and Yield in Sri Lanka.’

I am deeply indebted to Mr. Md. Shahiduzzaman, Chief, Scientific Oficer, Crop

Production Department, Dr. Md. Mainuddin, Chief Scientific Officer, Entomology Division, Dr.

Quamrul Ahsan, Chief Scientific Officer, Soil Chemistry Department, Mr. Mohammad Ali,

Senior Scientific Officer, Plant Pathology Division all at Bangladesh Tea Research Institute

(BTRI) for supplying valuable books and written documents without which writing of this paper

could not have been possible.

I am grateful to Mr. Joynul Abedin, Assistant Manager, Kamaichora Tea Estate,

Habiganj and Mr. Hassan Tariq, Assistant Manager, Rasidpur tea estate, Habiganj who provided

necessary information related to this Project Paper. I thank Mr. Safiq Ahmed Chowdhury, Chief

Executive, Finlay House, Srimongal for permitting me to collect field data from Kamaichora and

Rasidpur Tea Estate.

I deeply acknowledge the co-operation of Sanjoy Kumar Deb, Shah Fakhruddin, Shariful

Islam for their cordial help in processing the field data and collection of necessary data form the

field. Special thanks to Syed and his younger sister Munny for their cordial help in computer

processing and typing the whole project Paper. I can never forget those who in various ways

helped in collection of data and prepare the Project Paper.

V

ABSTRACT

A concise review of different important aspects of shade tree management has been

presented in this Paper. Special reference has been made with Rasidpur and Kamaichora Tea

Estates at Habiganj District. Major study areas covered are climatic and edaphic requirements of

different Shade Trees, optimum growing condition, major types of shade trees used in

Bangladesh, evaluation of growth performance in the field, silvicultural details, uses of shade

trees when harvested etc. Shade trees not only provide shade t the tea crop in addition they

provide numerous other benefits to the society like furniture, timber, charcoal, fodder, food, posts,

piles, pulp and paper, gum, tannin, fuel wood, pulpwood, resin, fertilizer, carved articles etc. Tea

plant needs (50–70%) diffused sunlight. High isolation above 0.3 g cal/cm–2/min–1 is not only

unnecessary but could be detrimental to photosynthesis by the tealeaves. The need of shade is

irrevocable especially in Bangladesh condition. It all points to the beneficial effects of shade trees

in conserving soil moisture during the driest part of the year, adding organic matter, effecting a

higher rate of increase in leaf area and accumulation of dry weight, reducing and buffering the

effects of fluctuations in soil temperature, reducing the leaf temperature, and allowing a

favourable partition of growth and valuation of the final product. Shade trees also act as

windbreak and shelterbelt and protect the main crop tea from mechanical damage done by strong

wind. To offset these undoubted good effects of shade trees there are also various risks. Shade

trees are always a potential source of infection by diseases but the risk is not very marked if shade

trees are treated properly. Shallow rooted shade trees compete with tea plant for nutrient and

moisture. Deep-rooted shade trees are out from this danger. The system of pollarding shade trees

and using their foliage as a green manure reduces the possible harmful effects of shade to a

minimum. A light stand of trees (70–140 trees/ha) is commonly recommended because heavy

shading (>200 trees/ha) will increase the formation of a large canopy due to limitation of sunlight.

At Kamaichora tea estate the average volume of Albizzia chinensis was 144.41cubic meter per

hectare. At Rasidpur tea estate the average volume of Albizzia odoratissima was 216.55 cubic

meter per hectare.

1

1. INTRODUCTION

Shade trees are those trees, which are used for providing shade over the tea plantation.

Planting of shade trees has become an integral component of tree plantation and management

throughout the tea growing areas in the world. Shade is possibly one of the most well investigated

research problems in tea. It attracted the attention of tea scientists world over, particularly since the

second world war; its role in tea growing was intensively debated in east Africa (child, 1961), Sri

Lanka (Joachim, 1961; Visser 1961 a; b), South India and Tockli (Hadfield, 1974a; b). The problem

acquired and added significance because of conflicting results that emanated from investigations

carried out in tea growing areas. Despite the controversies, it is quite certain that shade trees are

essential for modulating the tea environment of tea ecosystem and improving soil fertility and hence

shade tree is very important for optimum growth of tea.

Tea is a shade loving plant. 50-70% diffused sunlight is needed for better tea production

(Sana, 1989). Considering the intensity and duration of sunlight, daily 5 hours sunlight is optimum for

tea growth (Amin, 2003). If the intensity of sunlight is reduced, production increases to 40% (Amin,

2003). As cloudy sky is not favourable for tea growth, at the same time intense sunlight, excess

temperature, or too much cold may stunt the growth of tea plant. Tea cultivation becomes affected at

temperature higher than 30oC and lower than 12oC. Tea plant is always favoured by its natural state

of forest. Different research findings show that monthly mean temperature less than 65oF and more

than 85oF are unfavourable for tea cultivation. But in our country air temperature are often outside

this range (Kibria, 1986). Selection and management of proper shade trees are needed to overcome

this situation. Shade trees help by reducing the rate of evaporation of the soil moisture and thus

maintain a suitable humid atmospheric condition (Anon, 1984).

Bangladesh is producing tea under marginal climatic and soil conditions. A moderate shade,

which allows 50-70% sunshine in the plantation, is essential for the optimum growth of tea in

Bangladesh. So, right type of shade trees and their proper management is prerequisite for successful

tea culture. A large number of jungle trees have been tried in the past as shade trees but only a few of

them proved suitable in the long run (Chowdhury and Kibria, 1977). The use of leguminous species as

shade tree for tea is common in Bangladesh, India and Sri Lanka. Leguminous species are preferred

because they help in conservation of soil moisture by reducing the evaporation rate and thus maintain

2

a humid atmospheric condition under the canopy. Soil moisture conditions also help the growth and

physiological activity of the root system and subsequent utilization of mineral nutrients.

About forty percent of tea crop on a dry matter basis consist of the element carbon, which is

derived from the atmospheric carbon dioxide and is built up into plant tissues by the action of sunlight

in the presence of the chlorophyll of the leaf. Adequate light is needed for this process but not fierce

insolation. Particularly with a shade loving species like tea, the limit of increase of photosynthetic

activity is soon reached, and if by increased sunlight temperatures are raised to the point at which the

stomatal pores are closed to prevent wilting through excessive transpiration of moisture, the

photosynthetic activity suffers correspondingly since it is through these same stomata that the carbon

dioxide gas gains entry to the active portion of the leaf. Shade therefore has a beneficial effect on the

fundamental mechanism of plant nurture or growth in tropical regions. The damage caused to tea by

hail and sun scrotch, the one reinforcing the other, is too well observed to need more than a mere

mention. Shade trees make a definite contribution to protection from both of these mishaps.

Unprotected soil can absorb heat so rapidly that in tropical countries like Bangladesh, the

temperature of the soil surface may exceed 30oC (54oF) higher than the adjacent atmosphere. Not

only does the high temperature dry out the soil but it accelerates the loss of organic matter from the

soil by literally burning it away. The destruction of organic matter whether by microorganism or

direct oxidation involves chemical reactions. The velocity at which a chemical reaction takes place is

increased by rise in temperature, an increases of 10oC (18oF) doubling that velocity. As a corollary of

this destructive temperature effect the soil structure upon which soil fertility depends deteriorates

since organic matter in the realm of nature is the structure builder par excellence. Shade trees protect

the soil from all these.

Shade trees not only contribute directly to the maintenance of even temperatures and soil

moisture control but also by their natural leaf fall, or by pollarding provide vegetable mulch. The

mulch gives even more intimate protection than the foliage canopy and also makes a contribution to

soil conservation by impeding soil wash. Here again the action is two-fold, first by straight forward

blanketing of the soil and, even more important, by assisting in the rapid percolation of rainfall.

Mulch prevents the “running” of erosive soils. Shade trees with a more robust root system are capable

of overcoming the resistance of physically bad soils. Where their roots go, tea roots will follow. The

sub soling action of shade trees is not the least important of their function.

3

Shade tree is planted at the starting period of tea cultivation in the garden. It is better to plant

the shade one year before the planting of tea. Permanent shade trees take a long time to provide

optimum shade. For this reason temporary shade is planted for first 4-5 years (Sana, 1989). Shade

trees not only used as shade provider, but it also produce fuel wood timber, foods (leaves, pods or

flowers) for people fodder, production of tannins, gums, medicines and services like erosion control,

living fences, ornamentals, environmental protection (FAO, 1987). Shade trees are deep-rooted plants,

which grow better at the deep soil and hence do not interfere with the root system of the tea plant.

The height of the shade trees could become crucial in influencing the percentage of light

intensity that would ultimately reach the tea bushes under its canopy. The light intensity in the same

section shaded tea varies seasonally because of the movement of the sun. Thus, light intensity even in

the shaded section remains lower towards the later part of the growing season (September-October)

then in May-June due to movement of the sun. This also creates conditions of overlapping of shadows

from the shade trees and the degree of overlap is determined by the height of the shade trees. This is

also of great importance because if overlapping of shadows reduces the light intensity beyond a

minimum, it may adversely affect the yield of tea. We can fulfill our requirements by planting suitable

shade trees and by using wasteland in every tea estate through proper plantation programme.

4

2. OBJECTIVES

The main objective of this project paper is to scrutinize the over all management system of tea

garden and importance of shade providing species in the management of tea gardens of Bangladesh.

The general objectives can be summarized as follows:

I). To know the present status of Rasidpur and Kamaichora tea estates.

II). To identify the main shade trees used in Bangladesh tea gardens.

III). To know the importance of shade trees in tea plantation.

IV). To know the growing condition of shade trees including climate and soil factors.

V). To have knowledge about the interaction of tea plant and shade trees.

VI). To know about the planting procedure of shade trees along with the plants and other green

manuring crop and see the best performer in each garden.

VII). To know about the influence of shade on the incidence of pest in tea plantation.

VIII). To know about the provided spacing of shade trees in different tea gardens in relation to

topography and aspect.

IX). To know about the techniques of raising nurseries of shade trees.

X). To know about the rotation of shade trees.

XI). To know about various pest and diseases of shade trees and their control measure.

XII). To know the growth performance of shade trees in different site condition.

XIII). To evaluate different beneficial and harmful effect of shade trees on the tea climate.

XIV). To know about the selecting criteria of shade trees for specific purpose.

XV). To know about various utilization of shade trees other than providing shade to the tea

plants.

XVI). To develop suggestions for the improvement of efficiency and method of establishment of

shade trees about the shade.

XVII). To evaluate the present condition and growth performance of shade trees in the two

selected tea gardens in Bangladesh.

5

3. METHODOLOGY

Review of literature: Both field visit and personal communication were made to relevant

persons to obtain information on various aspects of shade tree management. Attempts were also made

to review various articles, books and journals to collect available literature in a number of libraries

namely library of Institute of Forestry and Environmental Sciences, University of Chittagong

(IFECU), Bangladesh Forest Research Institute (BFRI), Sholoshahar, Chittagong, Bangladesh Tea

Research Institute (BTRI), Srimongal, Maulavibazar.

Collection of Data/information: Personal Communication was made with forest officers,

Scientists of BTRI, managers of Tea Estates, to discuss different aspects of shade tree management.

Informations were collected systematically one after another and were enlisted in the notebook for

further assessment. Information were collected mainly in soil type, growing condition, environmental

requirements, planting technique of shade trees, types used, various beneficial and harmful effect of

shade trees to tea growth, shade vs. tea plant interaction, competition, role of shade in increasing tea

production, loping and uprooting technique, spacing, pest control, utilization of shade trees etc. The

relevant information and data was collected from Rasidpur tea estate, Hobiganj and Kamaichara Tea

Estate, Habigonj.

Reconnaissance survey: The author visited the tea estates to have a general idea of the every

pro and cons of management system of shade trees used in these gardens. For studying growth

performance of the shade trees in different locations data of height and d. b. h. of trees were taken

from two tea gardens, Rasidpur and Kamaichora. Under consideration species of shade trees were

Albizzia chinensis in the Kamaichora tea estate and Albizzia odoratissima in the Rasidpur tea estate.

30 m x 30 m random plots were taken, one in lower slope and another in upper slope in each garden.

Compilation of data: The collected data had been compiled into different sections under

different heads. Thus the data had been put into a systematic study work for seeding out the final

findings. Figures were taken directly from field, different books and international journals.

6

4. General description of rasidpur and kamaichora tea estate

4.1. Location and area

Rasidpur tea estate have established in 1978. The Rasidpur tea estate and Kamaichora tea

estate belong to Messers James Finlay and company. Rasid pur tea estate is situated about 20 Km and

Kamaichora Tea Estate 19 Km away on the East of Hobiganj thana under Hobiganj Districts. They are

on the way of Dhaka Sylhet high way. The total area of Rasidpur teas estate is 941.42 hectares of

which 414.75 hectares of land under tea only. The total area of Kamaichora Tea Estate is 754.72

hectares.

4.2. Tea Climate

The distribution of rainfall plays a vital role on the growth of the tea plant and shade trees.

While the temperature, photoperiod and latitude determine the cropping season of tea. An evenly

distributed rainfall through the year is needed for proper growth of tea plants. The hilly slopes area

where water drained away rapidly is favourable for the cultivation. The variation of temperature and

rainfall seasonally, influences greatly in production of tea. In Bangladesh, rainy season prevails from

April to September. Tea grows well in areas with low range of diurnal (daily) variation and fairly high

relative humidity (67-85%) during the greater part of the year. Maximum temperature ranges from

27.1o C to 28.6o C and minimum temperature ranges from 9.3o C to 20.4o C (Rashid, 1985). It is found

that 1270 mm annual rainfall is marginal for tea cultivation (Sana, 1989).

The annual rainfall recorded at Rasidpur tea estate was about 1692.7 mm in 1995 (Personal

communication). The average temperature in Kamaichora tea estate in January is 18.5oC and annual

rainfall was 1623 mm. So, the climatic conditions are favourable for the two studied tea gardens.

4.3. Tea soil

4.3.1. Ideal condition for tea soil

Tea is a deep-rooted plant and requires a loose friable soil and easily penetrable subsoil at a

depth of 0.8-1.5 m for its proper growth. Various experiments revealed that soil of sandy loam to

loamy textures are favourable for tea plant sand shade trees with a pH ranges from 5.0 to 5.5 soil rich

with organic matter rich is suitable for better growth of tea (Personal com). Shade trees provide

organic matter for tea plant.

7

Tea cannot stand in waterlogged condition. As such for an ideal condition, water table must be

below the root zone during the wet part of the year.

4.4. Soil and topographic condition

4.4.1. Soil texture

Soil texture is considered with size of mineral particles. It refers to the relative proportions of

particles of various sizes in a given soil. Tea is a deep rooted plant and requires a loose and friable soil

and easily penetrable sub soil at a depth of 0.91-1.5 m for its safisfactory growth. Medium loam to

sandy loam is considered ideal for root poliferation and optimum growth considering this the soil at

Rasidpur and Kamaichora tea estates are good for tea cultivation. PH value of soil at Rasidpur is 4.6

and at Kamaichora it ranges from 4 to 5.

4.4.2. Soil structure

Structure refers to the arrangement of soil particles into groups or aggregate and regulates the

air and water content of soil. Soil structure takes part in the formation of macro and micro pores and is

responsible for movement of air, percolating water and holding soil moisture respectively. The

arrangement of soil particles is quite suitable for tea and shade trees in Rasidpur and Kamaichora tea

estates.

4.5. Topographic condition of Rasidpur and Kamaichora tea estates

Topography of the tea area of Rasidpur and Kamaichora may be divided into two units.

(i) High Flat which are the higher valleys constitute 20% of the land, they are 15-20 feet

above the plain and dissected by narrow valleys created by water erosion, soil are well

drained water without rock fragment in the substratum, but gentler slopes than tillahs, the

soil are suitable for tea cultivation.

(ii) Low flat, which are the valley floor and constitute about 80% of tea land they are flat or

slightly undulating with moderately well drained and subjected to flush flooding up to a

day after heavy shower in monsoon. The topsoil is brown the substratum is gray may be

relatively rich in organic matter but subjected to water logging.

8

Table 1 Bangladesh tea research institute test the soil sample of Rasidpur tea estate and give the

following information.

No. Description Rasidpur-1 Rasidpur -2

1. Rock

2. Topography

3. Depth (cm) 0-23 0-23

4. Sample no 1 12

5. Textural class Sandy Loam Sandy loam

6. pH 4.6 4.6

7. Organic carbon (%) 0.97 0.87

8. Total nitrogen (%) 0.093 0.084

9. Phosphorus (æg/g) 28.3 26.1

10. Potassium (æg/g) 96.0 24.0

11. Calcium (æg/g) 61.2 77.8

12. Magnesium (æg/g) 7.4 5.0

No such type of tabular information is available for Kamaichora tea estate.

5. SHADE TREE

Leguminous or non-leguminous trees, which are used in the tea, coffee, and cacao gardens for

providing shade to the main crop, are called shade trees. In the cultivation of tea 50-70% diffused

sunlight is needed for the optimum production of tea. Shades are used to provide that range of

diffused sunlight in the cultivation of tea (Sana, 1989). There are about 159 tea estates in Bangladesh

which are spread over Sylhet, Srimongal, Surma-Valley, Zaintapur, Jaflong, Shamshernager, Juri,

Monu Doloi, Kulaura, Naypara, Vanugas, Longla, Chunarughat, Laskarpur, Satgaon in Sylhet

Division, at Brahmonbaria, Fatiqchari, Rangunia, Ramgar, Patiya (Kanchannagar), Dohazari-Sangu

Valley Banshkhali (Chanpur-Balgoan) in Chittagong, and Kapti (Wagga Chitmorom) in CHTs where

various types of leguminous trees are planted as shade trees to provide optimum growing condition

for the cultivation of tea plant.

5.1. Types of shade trees

Shade trees are of mainly of two types’ viz., permanent shade trees and temporary shade trees.

Permanent shade trees are planted for a longer rotation (about 40 years). It takes a long period to be

9

established. That’s why at the initial stage of plantation temporary shade trees along with the

permanent shade trees are planted to protect the tea plants from direct sun light. When the permanent

shade trees become established after 5/6 years, the temporary shade trees are removed (Sana, 1989).

5.1.1. Permanent shade trees:

Name of some permanent shade trees used in the tea estates of Bangladesh are given below:

Tetuya koroi (Albizzia odoratissima)

Melacana koroi (Albizzia moluccana)

Deris (Deris robusta)

Sada koroi (Albizzia procera)

Kala koroi (Albizzia lebbek)

Chakua koroi (Albizzia chinensis)

Ipilipil (Leucaena leucocephalla)

Siris (Albizzia lucida)

Sissoo (Dalbergia sissoo)

Minjiri (Cassia siamea)

Acacia lenticularis

Dalbergia assamica

Gravillea robusta

Akashmoni (Acacia auriculiformis)

Mangium (Acacia mangium)

5.1.2. Temporary shade trees

The following temporary shade trees are commonly used in the tea estates of Bangladesh:

Indigofera (Indigofera teysmanii)

Arhor (Cajanus cajan)

Cajanus indicus

Tephrosia candida

Gliricidia (Gliricidia spp.)

Dadap (Erythrina lithosperma)

Desmodium gyroides

10

6. SOIL AND CLIMATIC REQUIREMENTS OF SOME SHADE TREE SPECIES

It is difficult at times to find a concise summary of the site requirements of shade tree species.

Soil and climatic requirements of some commonly used shade tree species in the tea gardens of

Bangladesh are given below (F. A. O, 1987/15. NITROGEN FIXING TREES. REGIONAL OFFICE

FOR ASIA AND THE PACIFIC (RAPA). pp 61-70)

6.1. Acacia auriculiformis A. Cunn. ex Benth

Center of origin: Queensland, Papua New Guinea

Latitude range: 20 S – 7 S

Environment zone: Humid tropics

Minimum rainfall (mm): 1300 mm – 1700 mm

Annual rainfall: 1300 to 1700 mm

Dry season tolerance: 4 – 6 months

Mean maximum temp: 28 to 34 C

Mean minimum temp: 17 to 22 C

Mean annual temp: 24 to 29 C

Soil texture: Light/medium/heavy

Soil reaction: Alkaline/neutral/acid

Soil drainage: Seasonally waterlogged

Other soil requirements: Adaptable to most soil conditions, even poor,

sterile sandy soils

Main wood uses: Timber (4): pulp (2): fuel (2)

Forage uses: None

Other uses: Tannin (2): ornamental (2) erosion control () shade

()

6.2. Acacia mangium Willd

Center of origin: Australia, Papua New Guinea, Indonesia

Latitude range: 18 to 1 S

Environment zone: Humid and sub humid tropics

11

Minimum rainfall (mm): 1000 mm


Dry season tolerance: 2 to 4 months

Mean maximum temp.: 30 to 32 C



Soil texture: Medium

Soil reaction: Moderately acid, tolerates 4.2 pH

Soil drainage: Moist; tolerates seasonal water logging

Other soil requirements: Tolerates very poor sites and slight salinity; often

grows on creek and swamp margins.

Main wood uses: timber (2): fuel (2): pulp (1): Veneer ():

Forage uses: Browse (4)

Other uses: Plantation of water catchments; firebreaks;

ornamental purposes shade.

6.3. Albizia falcataria (L.) Fosberg

Center of origin: North Moluccas, Indonesia;

naturalized in much of Far East

Latitude range: 10 S to 3 N

Environment zone: Humid tropics


Annual rainfall: 2000 to 4000 m


Mean maximum temp.: 30 to 34 C

Mean minimum temp.: 20 to 24 C

Mean annual temp.: 22 to 29 C


Soil reaction: neutral/acid

Soil drainage: Free draining; moist

Other soil requirements: adaptable

Main wood uses: pulp (3): veneer (3): timber (3): fuel

(3)

12

Forage uses: Leaves (4)

Other uses: Tannin (): shade; cover for annual and

perennial crops in cluding coffee.

6.4. Albizia lebbek (L.) Benth.

Center of origin: Burma, India and Andaman Islands

Latitude range: 11 to 27 N

Environment zone: Semi-arid, sub humid and humid tropics









Soil drainage: Free draining

Other soil requirements: adaptable

Main wood uses: fuel (2): timber (2):

Forage uses: Leaves (2):

Other uses: gum (): Tannin (2): ornamental (2) erosion

control (2) shade tree.

6.5. Cajanus cajan (L.) Millsp.

Center of origin: India, Africa

Latitude range: 30 N to 30 S

Environment zone: semi-arid to sub humid

Minimum rainfall (mm):


Dry season tolerance: extensive

Mean maximum temp: 35 C

Mean minimum temp: 18 C

Mean annual temp:

13

Soil texture:

Soil reaction: neutral

Soil drainage: Thrives in light sandy soils best in deep

loams

Other soil requirements: cannot withstand water logging

Main wood uses: fuel

Forage uses: Leaves (3): browse (1); seeds (2): pods (2)

Other uses: windbreak (2): medicinal (): green manure

(2): food (1): shade

6.6. Dalbergia sissoo Roxb.

Center of origin: Indus to Assam; Himalayas


Environment zone: semi-arid, and humid tropics

Minimum rainfall (mm):




Mean minimum temp: –2 to +5 C


Soil texture: Light to medium

Soil reaction: Neutral to acidic

Soil drainage: Good; seasonally inundated

Other soil requirements: River beds and river flats

Main wood uses: timber (1): fuel (1): furniture (1):

cabinet work (1)

Forage uses: Leaves (3); pods (4)

Other uses: Honey flora (); erosion control, shade.

6.7. Gliricidia sepium (Jacq.) Steud.

Center of origin: Tropical Americas Naturalized in

Philippines and W. Nigeria


14

Environment zone: sub-humid, humid tropics

Minimum rainfall (mm): 800 to 2300 mm

Annual rainfall:





Soil texture: Medium


Soil drainage: Free draining; moist

Other soil requirements: Tolerates poor fertility soils

Main wood uses: fuel (1): timber (1)

Forage uses: Leaves (2)

Other uses: Bee pasture (): green manure (2): fodder ():

rat poison (): shade (1):

6.8. Leucaena leucocephala

Center of origin: S. W. Mexico and Central Guatemala


Environment zone: semi-arid, sub humid and humid tropics








Soil reaction: Alkaline/neutral

Soil drainage: Moderately free draining

Other soil requirements: will not tolerate strongly acid soils or

waterlogging

Main wood uses: fuel

Forage uses: leaves (2)

15

6.9. Matching Species with Site

To find Shade Trees whose climate and soil requirements match conditions at the planting site,

the most important factors to consider are climate and soil characteristics. The choice of species

depends on the intended use, availability of planting materials and adaptability. Species selection,

whether from indigenous or exotic sources, involves matches species’ climatic and soil requirements

to the conditions at the plating site. The most important climatic factors to consider are amount and

distribution of rainfall and extremes in temperature. Principle soil properties include depth, texture,

fertility and pH. The best way to identify well-suited species is through a series of well-planned

species. The actual climatic conditions at the planting site may differ from those recorded at the

nearest meteorological station. In this case, it will be necessary to estimate or predict actual

conditions. Temperature variations are mainly due to changes in altitude. The commonly accepted

gradient is 0.5o C per 100-meter rise in elevation. Variations in rainfall cannot be predicted so rapidly.

The rainfall at the nearest meteorological station cannot be accepted unless the topography is fairly

similar between the two areas. Soil pH is important because it influences the availability of nutrients.

Some species are more adapted to alkaline soils (high pH) and other to acidic soils (low pH).

7. Growth performance of shade trees

The growth performance of shade trees was assessed in the field by visiting two tea estates at

Habigang district. The results are discussed here:

In Kamaichora tea estate in the lower slope the average height of the Albizia chinensis was

11.65 m, average diameter was 23.12 cm. Average volume per tree was 0.3842 m3 and average

volume per hectare was 145.14 m3. In the upper slope, the average height of the trees was found

11.21 m, average diameter 22.79 cm, average volume per tree was 0.3592 m3 average volume per

hectare was 143.68 m3. Considering upper and middle slope in the whole tea estate average volume

was 144.41 m3/ha.

16

Table 2 Showing the growth performance of A. chinensis and A. odoratissimaxin in Kamaichora and

Rasidpur tea estates respectively

Name of the

Tea Estate &

corresponding

species

Plot Average

height

(m)

Average

diameter

(cm)

Average

vol/tree

(m3)

No. of

trees in

30 m x 30

m plot

Average

vol/ha

(m3/ha)

Average

vol per

hectare

of the

garden.

(m3/ha)

Kamaichora

(Albizia

chinensis)

1 (lower

slope)

11.65 23.12 0.3842 34 145.14 144.41

2 (upper

slope)

11.21 22.79 0.3592 36 143.69

Rasidpur

(Albizia

odoratissima)

1 (lower

slope)

13.91 28.10 0.6776 29 218.00 216.55

2 (upper

slope)

13.17 27.32 0.6065 32 215.10

In Rasidpur tea estate in the lower slope the average height Albizia chinensis was 13.91 m,

average diameter was 28.10 cm, average volume per tree was .6776 m3 while average volume per

hectare was 218.0 m3. In the upper slope, the average height was 13.17 m, the average diameter was

27.32 cm, and average volume per tree was .6065 m3 while average volume per hectare was 215.10

m3. Considering upper and middle slope in the whole tea estate the average volume was 216.55

m3/ha.

It is observed from the data given in table 3 that the average height and diameter of the trees

growing in the lower slope is greater than the averages of those parameters in the upper slope.

Consequently the average volume of A. chinensis per hectare in the lower slope is 1.46 m3 higher than

that of upper slope in Kamaichora tea estate and the average volume of A. odoratissima in lower slope

per hectare is 2.90 m3 higher than that of upper slope in Rasidpur estate. This may be due to the fact

that in the lower slopes, there is a higher accumulation of litter and higher moisture content in

comparison with the upper slope. The age of A. chinensis is 18 years and A. odoratissima is 21 years

in the tea estates. Rotation of both the trees is considered to be 40 years in the tea estates. So, at the

17

end of the rotation, a volume of 320.91 m3/ha of A. chinensis and 412.47 m3/ha of A. odoratissima can

be obtained.

8. Silviculture of shade trees

An ideal shade tree is one of which the foliage forms a single layered canopy which cuts out

most of the infra-red rays but allows sufficient visible light to pass through the bush surface and does

not compete with the tea for nutrients and soil moisture. Albizzia chinensis (sau) almost satisfies these

ideal requirements. Other shade tree species found suitable for shading tea are A. odoratissima, A.

lebbek, Acacia lenticularis, Derris robusta and Dalbergla sericea. Indigofera leysmanii is a very

popular temporary shade trees species. Their important characteristics are:

A. chinensis: Deep root system. In droughty years it comes into full foliage only about the end

of April; very prone to red-rust and cankers from very early age.

A. odoratissima: Deep root system, easy and quick to establish, susceptible to red-rust and

plant lice in the nursery, prone to attacks by all kinds of leaf-eating and sucking pests, as well as to

wood and bark-borers.

A. lebbek: Very deep root system, is slow to establish and in early stage is susceptible to all

common pests and red-rust but later on grows well and provide good shade, rarely cankers, but has a

short life.

Acacia lenticularis: Deep root system, leaflet size and growth form similar to A. odoratissima;

has sharp thorns on the smaller branches.

Derris robusta: Deep root system, wood is hard, susceptible to attack by leaf-eating caterpillar

Baradessa omissa but virtually free from other pests and diseases and easy to establish; used in

mixture, with lopping makes a reasonable shade canopy.

Delbergia seficea: Deep root system, fairly quick growing, leaf size and growth habit similar

to A. lebbek, presently free from pest and diseases, difficult to raise from seed but grows very well

from root cuttings.

Grevillea robusta (Poteaceae) is a large, evergreen, hardy tree that grows to a height of 20-

30m. When lopped at a height of 5-6 m, it spreads out at the top, forming a good canopy of foliage,

18

and does not complete unduly with the tea. Due to a constant dropping of its leaves it produces heavy

mulch, which benefits the soil as organic matter.

Albizzia moluccana (Leguminosae) is a very large, fast-growing, evergreen tree, which grows

to a height of more than 30 m with a spreading habit and light feathery foliage. It has a canopy of a

mean of 13-15 m in diameter.

Erythrina lithosperma (Leguminosae), commonly named Dadap, is a fast growing tree and

easy to establish.

Gliricidia maculata (Leguminosae), is a fast growing, leguminous, medium sized, thorn less

tree, which reaches up to 10 m in height. It provides a large quantity of green material compared to

Dadaps and stands harder to more frequent lopping. Furthermore the tree is relatively free of pests and

diseases. Its main advantage is the ease with which it can be established. Gliricidia is commonly

established from cuttings, though it can be grown from seeds as well.

Acacia pruinosa and Acacia decurrens (Leguminosae) are small trees, which remain in a tea

field for 5-6 years, but do not stand up to lopping very well.

Indigofera teysmanzi: Shallow root system but is very quick growing and easy to propagate

by seed, cuttings or air-layerings, gives effective shade within one year at 2 X 2 m spacing, but if

uncontrolled its becomes susceptible to storm damage; with good management it can be maintained

for five to six years; apart from a hairy caterpillar and green aphids it is fairly pest free but suffers

from red-rust.

Choice of shade trees for single species of mixed species use is determined by the following

factors:

1) Growth habit

2) Pest and disease resistance

3) Economic life

4) Resistance to storm damage

5) Depth of root system

6) Suitability to the soils and climate of the district

19

8.1. Mixture of shade tree species

A) Intimate Mixtures: From the point of view of reducing the damages of epidemic pests and

diseases, it is desirable to use a number of species in mixture. The ideal mixture called 'intimate

mixture' is one where no two trees of a single species are adjacent to each other; a minimum of four

species is required for this combination:

a) Square planting

A B C D

C D A B

A B C D

C D A B

b) Triangular planting

A B C

C D A B

A B C D

C D A B

B) Non-intimate Mixtures: This is followed when use of intimate mixtures is not possible. The

dispersion of shade in this situation would be:

1) Tea and shade square planted

a) Two permanent shade species

A B A B

X X X

B A B A

X X X

C A B C

X X X

A B C A

20

Where X = temporary shade

b) Three permanent shade species

A B C A

X X X

B C A B

X X X

C A B C

X X X

A B C A

Apart from dispersion, the following factors should be considered in the arrangement of the

individual shade tree species in the mixture:

a) Relative crown diameters of species.

b) Relative potential rotations of species.

Large-crowned species should alternate with smaller ones; short rotation species should also

alternate with long rotation species.

8.2. Spacing of shade tree

Spacing is an important factor of management of shade trees in the tea gardens. Spacing which

must be provided varies with place, aspect of the slope, Phenology of the plant, rooting

characteristics, competitions with the tea crops etc. Following are some suggested spacing of shade

trees applicable for Bangladesh condition.

a) Temporary shade: 2 X 2 metres initially, thinned out to 4 X 4 metres later on.

b) Permanent shade: (based on shade given by mature A. chinensis).

Light shade: 15.24 m x 15.24 m (50' x 50) triangular or 13.7 m. X 13.7 m (45'x 45') square or

wider.

Medium shade: 13.7 m x 13.7 m (45' X 45) triangular or 12.2 m x 12.2 m (40'X 40') square.

21

Heavy shade: 10.67 m x 10.67 m (35' x 35) triangular or 9.14 m X 9.14 m (30' x 30') square or

closer.

For teelas and steeply slopping land it is better that a shade spacing of the type described as

heavy is used.

Table 3 Spacing of shade trees used in the Rasidpur and Kamaichora tea estates depending on location

(in m.)

Serial

No.

Kinds of shade trees Slope Plain/Fairly

slope South/west East North

1. Permanent shade tree 4.5 6 7.5-9 6

Initial stage after thinning 9 12 15-18 12

2. Temporary shade tree 2.25 3 3.75 3

8.3. Lay Out Of Tea / Shade / Green Crop

A standard layout of tea, shade tree and green crop suggested by D. L Sana, a famous tea

scientist of Bangladesh Tea Research Institute have been given below. It may vary in different

locations and tea-shade tree combinations. In Bangladesh tea, the temporary shade species, Indigofera

teysmanii is grown at spacings 3.0 to 4.6 m. (10′- 15′) depending on the topography of plantation.

When the permanent shade trees, viz. Albizzia odoratissima, A. lebbek and Derris robusta become

established after 5/6 years, the temporary shade trees are removed. The spacing of permanent shade

trees, varies from 3x3 m. to 5x5 m. (10'x10' to 15'xl5') square. While planting, the south and

south-west slope of the tillah should be avoided unless the proper shade is established beforehand.

A planting design for a composite tea plantation, which is adopted in principle, is shown in the

underlying figure. Bogamedeloa is sown in lines at distance of 240 cm. while the tea is planted at

spacing 120 cm. x 60 cm. The permanent shade trees are planted 6m x 6m. square, but temporary

shade at 3m. x 3m. spacing. One row of green crop is placed alternate of two rows of tea. The

placement of temporary shade may be adjusted along the shade trees or separate line at 3 m. apart.

22

23

8.4. Planting of shade trees

A general method for raising plantation of shade trees is suggested below:

(a) Method of planting: The best method is to plant out as one year old seedlings sleeve

grown or with a bethi. Where this is impracticable, good results can be had by carrot planting in

which roots are shortened to 30 to 45 cm in length while retaining as much of the laterals as possible.

At the time of planting, holes 60 cm deep (or even more for A. odoratissima) should be dug and 450 g

TSP plus 9 to 14 kg dry well rotted cattle manure per plant should be mixed with earth. In mature

square or triangular planted tea, it is usually best to remove a tea bush to plant a shade tree. In mature

close hedge planted tea, when inter planting permanent shade in the line of the hedge, two or better

three tea bushes should be removed to make way for a shade tree. Before lifting, the plant should be

pollarded at I to 2 in from ground irrespective of the method of planting. The cut should be protected

with a lump of fresh cattle manure pressed w ' ell around the stem.

(b) Time of planting: The most suitable time is when the soil is moist as it is between

February and April; in drought areas planting out may be delayed till some rain has fallen..

(c) Manuring of shade: Young shade trees may be manured as follows: Trees under 2.5 m in

height - 500 g TSP applied in broad ring of approximately 1.5 m diameter. Trees between 2.5 in and 4

in - 1.5 kg TSP in broad ring of approximately 3 m diameter.

(d) Maintenance of shade: To maintain a satisfactory shade canopy throughout the life of a

section of tea, the original shade stand should be interplanted with new shade, at such a pace that the

new shade is well established before the original shade comes to the end of its useful economic life.

Following the planting of shade either in mature tea that is being reshaded or in young tea, good

maintenance is essential to ensure that shade grows and the single-leaf canopy is achieved. The

temporary species will require frequent lopping until they are finally removed. In the first few years

after transplanting, the permanent species will require regular rounds of prophylactic sprayings

against pests and diseases. Once the permanent species takes over, it will be necessary to ensure that

there is only a single-leaf shade by lopping off the lower branches.

24

9. Propagation of shade trees

i) Selection of seed: Seed should be obtained from an area where the species is known to grow

well. Seed may be selected locally from species, which grow particularly well in that locality. The

mother tree (or trees) should possess good growth habit and be free of pests and diseases.

ii) Seed collection: Seed should be collected from the tree and not from the ground. In the

case of leguminous trees the pods should be collected only when they are ripe. Ripe seed will have

lost its greenish colour and be hard to the touch. The pods should be collected by lopping off the

branches to which they are attached when the majority turns brown they are stored on clean ground or

on a tarpaulin until the foliage dries out. The seeds are extracted from the pods by thrashing them with

long sticks and then winnowing.

iii) Seed treatment and storage: Seeds should be mixed with any insecticidal dust, for

example, 5 per cent gammaxene dust at the rate of 30 g per 15 kg seed. Seeds can be stored until

sowing time but it must be kept in a well-ventilated cool and dry place, either in sacks or shallow

boxes having wire gauze bottoms and tops.

iv) Preparation of sleeve nurseries: Polythene sleeves in 250 gauze of 25 to 30 cm width

lay-flat and 40 to 50 cm lengths are adequate. These could be filled with 4:1 parts of good soil and dry

well rotted cattle manure respectively. Mixing 0.5 kg TSP per cubic meter of the soil and cattle

manure mixture is beneficial. Soil should not be compact. Two to three seeds are planted in each

sleeve and when the seedlings become about 15 to 20 cm tall, the weaker seedlings are pulled out

leaving the best ones to grow. The best plants can be planted out at any time of the year as soon as

they become more than 1 m in height. To prevent the taproot from penetrating into the soil below the

sleeves, the sleeves should be shifted at frequent intervals.

v) Time of sowing: Seed can be sown any time from January to May with the provision of

irrigation facilities. March/April is, probably, the best months for sowing seeds. Hard-coated seeds

may be put in sacks and alternating soaked and dried three or four times. Seeds with very hard seed

coat may be soaked in 50 per cent sulphuric acid for 30 minutes, then washed in sodium bicarbonate

or ordinary washing soda, and sown.

vi) Drainage of shade nursery: Good drainage system should be provided in the shade

nursery area to allow the roots to grow to a good depth.

25

vii) Control of pests and diseases in the nursery: Prophylactic sprayings at monthly rounds

with suitable insecticides and with a fungicide at fortnightly intervals between April and June help

prevent damages by pests and diseases

10. Establishment of shade

In view of the seriousness of the situation immediate programmes of reestablishing shade

should start or should be intensified in many estates, both in new clearings as well as in nature tea

fields. Permanent shade should be established early during the period of rehabilitation with grass, so

that the shade trees will serve their purpose by the time the tea is planted. The grass surrounding every

point of planting should be kept low in order to admit light and prevent a smothering of the shade

plants. The shade trees should be planted in the rows where the tea is anticipated to be planted. In

mature tea fields it is advisable to plant shade trees soon after the pruning of the tea to facilitate a

speedy establishment of the shade plant. Shade reduces transpiration by affecting the microclimate of

the leaf, which also includes a reduction of solar radiation and wind speed.

Figure 1: High and low shade of Grevillea and Dodaps in tea plantation

A light stand of trees (70-140 trees/ha) is commonly recommended because heavy shading

(>200 trees/ha) will increase dormancy and will influence the formation of a larger canopy due to the

limitation of sunlight. Shade trees should be planted as a mixed stand of high shade, like Grevillea,

and low shade, like Erythrina lithosperma (Dadaps) or Gliricidia. For the purpose of establishing

such a system of shade the high shade trees have to be planted at a wider spacing with the low shade

trees, which are to occupy an intermediary position

26

Suitable shade trees for high-grown teas are Grevillea robusta, spaced 12m x 12m, giving

approximately 74 plants per ha, Erythrina lithosperma, Acacia pruinosa, and Acacia decurrens spaced

6m x 6cm. For the mid- and low-grown teas, the author recommends Grevillea robusta (12m x 12m)

and Gliricidia maculata (6m x 6m).

11. Effect of shade per se

The very fundamental issue of shade problem is whether or not a reduction in illumination

intensity by shade will have a positive effect on yield and growth of tea. Preliminary experiments

using overhead mechanical shade of split bamboo laths to reduce light intensity by about half showed

that growth, yield and weight of prunings of teas under the bamboo screens were significantly higher

than those under full sun (Barua, 1960). Although the magnitude of increase somewhat varied in the

experiment, the inevitable conclusion was that shade indeed had a beneficial effect on the growth and

yield of tea, at least under Assam conditions.

Although bamboo screens (mechanical shade) in the experiments mentioned above helped in

conserving soil moisture during the driest, part of the year, it is possible that roots of young shade

trees and tea would compete for available moisture in the top 30 cm of soil profile. The degree of

competition may vary according to the species of shade trees but properly managed stands of mature

and good shade trees like A. chinensis and A. odoratissima would also help conserve soil moisture,

and may even negate the effect of competition, if there is any. For example, in south India, soil

moisture level at two depths-0 to 23 cm and 23 to 46 cm, shaded by Erythina lithosperma (Dadap)

was higher than in un-shaded-tea-areas during the driest part of the year from October to March, and

there was no over-competition for moisture between tea and shade trees (Venkataramani, 1961). The

basic point is that a properly managed stand of mature, deep-rooting shade trees is unlikely to

compete with tea for water during a period of water scarcity. In fact, some species of shade trees may

even help conserve moisture. Moreover, the variation in crop yield under different shade trees is also

closely related to soil moisture at 2.5 cm to 45 cm soil depth at the end of March in a drought year;

and strong positive correlation exists between the soil moisture and yield (Barua and Dutta, 1961).

12. Shade trees and litterfall

An additional advantage of shade tree is the organic matter it adds to the soil. The total weight

of organic matter in the form of leaf, twig and pod droppings by a mature stand of A. chinensis trees

spaced 12 in square comes to around 5 tonnes per ha, with a nitrogen content of 77 kg per ha (Dutta,

27

1960). In east Africa, the total annual leaf fall from Grevillea robusta shade trees. and tea bushes is

6.5 tonnes dry matter per acre (Goodchild and Foster-Barham, 1958); it is much higher than what is

common in Assam.

The actual quantity of litter from shade trees will vary with the species, age, spacing, locality,

and. manuring etc. The litter from a stand of a A. chinensis trees casting moderate shade (50 to 60- per

-cent light intensity) adds annually 2500 to 5,000 kg; dry matter per ha with a nutrient content of N

-63 to 126 kg; P2O5 - 1,8 to 36 kg; K2O – 22 to 44 kg; CaO–32 to 64 kg; MgO- 16 to 32 kg ha–1

(Hadfield, 1974a). Complete removal of litter from shaded plots is capable of causing an approximate

15 per cent drop in yield, but an addition of the litter to plots in full sun plots would also raise the

yield to an equal extent though it is not clear how the yield increase is affected

It is worth noting that nitrogen fixing capacity of the leguminous shade trees in, tea, is still a

suspect and precious little is known of the amount of atmospheric nitrogen fixed by the roots of these

legurninous trees. However, it is most likely that in the presence of large quantities of added soluble

nitrogenous fertilizers in tea fields, the fixation of nitrogen by the shade trees is greatly reduced

(Wight, 1959b; Visser, 1961a).

There is some evidence that leaf area and dry weight increase significantly under shaded

conditions. Shade is also effective in enhancing the rates of increase of the leaf area and dry weight

with age of leaf, and in decreasing the leaf area, dry weight ratio. The rates of increase of leaf area,

dry weight and dry weight per unit leaf area are important parameters for yield projections of tea, and

shade appears to have a positive influence on them.

Expectedly, soil temperatures recorded during summer are much higher in full sun than under

50 per cent light - possible under a stand of shade. Also during much of this period aeration is

inadequate as soil water remains at or above field capacity, but shade tree roots can help in improving

soil aeration because of their capacity to penetrate deep into the soil. This apart, mature tea shaded by

A. chinensis and manured with 84 kg N per ha as ammonium sulphate is conducive to the growth of a

higher proportion of feeding roots, during the growing season (April to October) than those exposed

to full sun (Barua and Dutta, 1961), and this may well be a premium against drought damage.

An important aspect of shade is its influence on the build up of diseases and pests, at times

favourable but most times unfavourable. Mites, for -example, are generally adverse to shade, but

28

blister blight and black rot thrive well under shade. Red spider and other tea mites thrive well under

unshaded condition (Das, 1961; Banerjee, 1969). Mite damage is more severe on unshaded rather than

shaded tea. Just the opposite effect has been reported from Sri Lanka (Danthanaryana and Ranaweera,

1972), though in Indonesia the incidence of orange mite on tea increased considerably following

removal of shade trees (De Weille, 1959).

13. Shade and light intensity

From the physiological point of view, perhaps one of the most important effects of shade is its

indirect influence on growth of tea. Net assimilation rate (NAR) of young tea ranging from extreme

China to extreme Assam type is related to low light intensity, ranging from 20 to 100 percent. In all

tea varieties, leaf area remains nearly steady between 50 per cent intensity and full sunlight. However,

the leaf area is maximum under 35 to 50 per cent light intensity but is minimum in full sun. In

contrast, the weight of the whole plant does not vary significantly between light intensity of 50 and

100 per cent.

The total plant weight being the product of NAR and leaf area, it follows that growth will be

maximum in reduced light intensity provided the reduction in leaf area between light and partial shade

is very large. The optimum light intensity for maximum growth will then shift more and more towards

full light as the difference in. leaf area between fun light and reduced light gradually diminishes

(Barua, 1961). The yield of plucked shoots in all cultivars is generally maximum under 50 per cent

light intensity - the relative values for the four light intensities being 50, 35, 100 and 20 per cent

(Barua, 1961).

14. Shade and tea leaf temperature

At ambient temperatures of 30o to 32o C leaf temperatures of horizontal and erect-leaf tea in

full sunshine may reach 40o to 45o C, but in shaded leaves they remain 10 to 20 C above the, ambient

value. However, fully exposed horizontal leaves are generally 2o to 4o C, warmer than erect or semi

erect leaves, but a leaf temperature of 40o C is common to all types of leaves under unshaded

condition when the ambient temperatures are from 30o to 32o C (Hadfield, 1968). This temperature

range is common in Assam during April to October when tea productivity is at its peak. Apart from

temperature effect, -net photosynthesis also declines sharply when leaf temperature goes beyond 35o

and between 39o and 42o C it virtually stops. But respiration continues up to 48o C, above which, leaf

tissues get irrevocably damaged (Hadfield, 1968).

29

15. Effect of shade trees on light climate

The measurement of light, intensity, its duration and spectral analysis in shade and, sun

provide a fairly adequate characterization of the light regime, which is optimal for growth and

productivity of tea. The spectral composition of light in full sun, and under shade varies between 400

and 1,400 n m at different hours of the day and times of the year under-varying weather, conditions.

The light pattern under shade also varies with the distance from the tree, hours of the day time of the

year and cloud cover of the sky (Hadfield, 1974a).

Shade trees absorb a considerable amount of radiation of different wavebands from the solar

spectrum. Even under light, shade, on a bright summer day, there is a marked reduction of those

wavebands, (400-450 nm and 600-700 nm) associated with action peak of photosynthesis. This means

that a considerable amount of useful radiation is removed from the solar spectrum before it reaches tea

canopy. However, shade tree canopy of this nature also absorbs a large amount of harmful infra-red

radiation-over 70 per cent of the total present in full sunlight. It is likely that this reduction in infra-red

radiation and hence cooler leaves compensates well for the reduction of potentially useful visible

wavebands under climatic conditions of high ambient temperatures and low wind speeds common in

Assam (Hadfield, 1974 b).

The light pattern on the surface of individual tea bushes in the north-south and east-west rows

between rows of shade trees under diverse growing conditions is a heterogeneous mixture of light

intensities, varying from full light to very low light, and cannot therefore be properly expressed as,

percentage of full sunshine. Under sunny conditions some bushes receive full sunlight but those in

dense shade receive no sun flecks and yet a third category receives sun flecks light of greater or lesser

intensity. The proportion of each class of bushes receiving light of different intensity varies

throughout the day depending on the total irradiance received from the sun (Hadfield, 1974 a, b);

therefore light absorption and distribution are rather dynamic with no definite pattern emerging for

generalization.

Shade pattern under 10 common species of shade trees varies greatly because of difference in

light transmission through their canopies and this difference is species specific. Indeed, if the canopy

characteristics and light transmission by different species of shade trees are known, it is often possible

to screen potentially useful shade trees. By use of the area survey method' (Evans, 1956), it is even

possible to eliminate many species before the field trial stage and only those trees which allow an

30

adequate proportion of light in the form of sun flecks to penetrate the canopy can be selected right

way instead of going for the time consuming and expensive replicated trials (Hadfield, 1974 a).

The distribution of light intensity as a percentage of visible radiation at the bush surface also

varies with the plant types having different leaf angles, such as, those ranging from erect to droopy

leaves. But in most, cages, the first 10 cm layer of leaf absorbs 70 to 90 per cent of visible- radiation

incident on its surface and visible light reaches the lower layers of leaves in the canopy' either through

gaps in the canopy or by reflection from upper leaves (Hadfield, 1974 a).

Light penetration into tea canopies also depends on leaf angle. Generally the erect and

semi-erect leaves allow a greater penetration of light than the horizontal leaves where light is

restricted only to the top layer of the foliage (Hadfield, l 974 a). This finding could be of considerable

practical importance in the selection of plant architecture suitable for optimal growth and productivity.

16. Shade and partition of growth

In a classical Shade and partition experiment at Tocklai, the effect of tree shade (A. chinensis)

and mechanical shade (bamboo lath screen) on the productivity of tea cultivars was compared against

those in full sun, with and without optimum nutrients (Hadfield, l 974 a). The cultivars selected

ranged from hybrids to extreme Assam variety in Assam, and weights of pluckings and prunings were

recorded continuously for 10 years. In the eleventh year one complete block was uprooted to record

the weights of roots and frames for each cultivar in each treatment. The main conclusions were:

a) Yields of plucked shoots over the 10 years period by all cultivars were at maxima under

shade trees and minimum under the screens with the sun plots occupying an intermediate position.

But the screen plots out yielded the sun plots once these plants covered the ground by profuse growth.

b) The total biomass was also maximum under shade though the difference in biomass weight

between sun and mechanical shade was very small. But the weight of root was highest in full sun

followed by shade and mechanical shade.

c) The most significant aspect was that even the addition of balanced nutrients (NPK and

micro-nutrients in some years) in plots under full sun or in mechanical shade failed to compensate for

the decline in yield in unshaded tea.

31

Perhaps the most important effect of shade tree is the favourable partition of growth between

different plant organs that it causes. The ratios of plucking to prunings, plucking to total growth, and

top to root are generally the highest under shaded trees. Indeed the percentage of plucking to total

growth (Plucking plus pruning plus frame plus root), that is, the harvest index was highest under a

shaded tree. It is possible therefore that shading diverts a relatively larger fraction of the assimilates

towards the production of pluckable shoots which economically are the most useful fraction of growth

(Magambo and Cannell, 1981).

17. Shade effect on quality of made tea

A related interesting but important aspect of shade is its overt influence on the quality of made

tea although a causal explanation is lacking. The strength and colour of liquor appear to improve

significantly in 50 per cent light though infused leaf from plants in full light was categorized as of

high value (Dutta and Basu, 1955). The main conclusion to be drawn from this and related studies is

that reduction of light intensity to about 50 per cent of full sun does not have any adverse effect on the

quality of made teas; if anything, the overall character of the teas slightly improves at relatively low

light intensity (Barua, 1961).

18. Current perspective

The experience in northeast India would suggest that shade does have an agronomical and

physiological role to play in enhancing productivity of tea. It is of interest that the role of a shade is

now being reassessed even by traditionally non-shaded tea growing countries. Nevertheless, there are

still some problems of assessing and measuring the true effects of shade.

First, it is necessary to know precisely the amount of atmospheric nitrogen that can actually (it

at all) be fixed by the different leguminous shade trees used in tea areas, and the probable and possible

influence of environmental factors like temperature, light intensity, day-length and their interactions

in the fixation of nitrogen. This problem is of considerable topical interest as currently a search is on

for more efficient nitrogen fixers among legumes to fertilize tea soils.

The other aspect is that very little information is currently available on suspected competition

between shade trees and tea. Although devising parameters for measuring competition is no doubt

difficult, but if there is any competition at all is not clear. Perhaps, use of isotopes will be helpful. It is

also necessary to evaluate the effect of shade on the microclimate in the immediate vicinity of the tea

32

plants, including soil climate of the root zone as it has great influence on nutrient uptake and other

physiological processes.

The basic question, however, is whether or not there are tea genotypes that would grow better

in sun (sun-lover) or under shade (shade-lover). A survey of germ-plasm would help in identifying

plants of either category. This does not however overlook the basic fact that penetration of light into

the bush canopy is dependent on the leaf orientation.

The height of shade trees could become crucial in influencing the percentage of light intensity

that would ultimately reach the bushes under its canopy. The light intensity in the same section of

shaded tea varies seasonally because of the movement of the sun. Thus, light intensity even in the

shaded section remains lower towards the later part of the growing season (September-October in

Assam and the Dooars) than in May-June due to movement of the sun. This also creates conditions for

overlapping of shadows from shade trees and the degree of overlap is determined by the height of the

shade trees. This is of great significance because if overlapping of shadows reduces the light intensity

beyond a minimum, it may adversely affect the yield. Judged in this context, none of the shade

species currently being used will appear to be ideal, except perhaps A. chinensis which comes closer

towards the concept of an ideal shade, but this species is prone to canker and is dying out in parts of

Assam. Despite intensive search for alternative species for the last few decades both among

indigenous and exotic species, an ideal species of shade tree still remains as elusive as ever. However,

the recent approach to propagate shade trees by tissue culture may provide opportunities to develop

the ideal plant by genetic recombination (Phukan and Mitra, 1983).

1n summation, the need for shade trees is irrevocable if one were to go by the hard evidence

collected in the past 40 years. It all points to the beneficial effects of shade in conserving soil moisture

during the driest part of the year, adding organic matter, effecting a higher rate of increase in leaf area

and accumulation of dry weight, reducing and buffering the effects of fluctuations in soil temperature,

reducing leaf temperature and allowing a favourable partition of growth without affecting the quality

and valuation of the final product. All these are of consequence in enhancing productivity of tea but

physiological aspect of shade is also worth noting.

33

19. Management of Shade Trees

It has been noted that monthly mean temperatures less than 65o and more than 85o F are

unfavourable for tea cultivation. But in our climate air temperatures are often outside this range

(Kibria, 1986). Shade trees help by reducing the rate of evaporation of the soil moisture and thus

maintain a suitable humid atmospheric condition. So, there is a great need of shade trees for suitable

growth of tea. (Usually trees, which grow within the pH range of 5.0-6.0, are used as shade trees in

the plantation. Deep-rooted species which retain leaves during dry weather (e.g. Albizia odoratissima)

could be used (Anon, 1984). Particularly in our climate, successful tea culture mostly dependent on

selection of right type of shade trees and their proper management.

Figure 2: Mixture of various shade trees (Ipil-ipil, Shada koroi, Chakua koroi) used at Rasidpur Tea Estate

Previously a large number of forest trees have been tried as shade trees but only a very few of

them have proved suitable (chancing and Kibria, 1977). When there is a continuous operation, in that

cases leguminous trees are preferable to use as shade trees.

Generally Albizia lebbek are used as shade trees in most tea gardens of Bangladesh. Albizia

chinensis is a fast growing shade tree and produce excellent shade but it is more sucptable to canker

disease than any other species of Albizia (Hassan and Chowdhury, 1964). The range of pH values for

the satisfactory growth of Albizia chinensis is 5.5 to 6.5 the optimum growth is found at pH 6.0. It

prefers slightly to moderately acidic soil (Choudhury and Kibria, 1977).

34

Another vital use of trees is they can be used as windbreaks. Single row windbreaks are

considered to be better than multi row windbreaks since the farmer gives protection against wind

vetocity for a greater distance (Kibria, 1986). While planting shade trees at the early stage of tea

cultivation, spacing should be carefully maintained. In care of permanent shade trees, the distance

between two trees should be 9-12 m. depending on the site condition.

The system of pollarding shade, trees and using their foliage, as a green manure reduces the

possible harmful effects of shade to a minimum. By the very act of periodic lopping the rate of growth

of a tree is controlled and at the same time, the proportion of useful foliage to probably unwanted

wood is favorably altered, just as pruning a tea bush encourages crop growth. A long-term policy of

shade should make provision for replacement by building up an age-rotation of trees. This will

involve denser planting than the optimum at first so as to get shade quickly, followed by thinning by

stages. The ideal to be aimed at is rows of shade at two or three different stages of maturity, and to

achieve this some immature trees will have to be sacrificed in the initial stages of the programme.

Thinning of the stand is best done by rows so as to ease the problem of felling and removal

and should always be preceded by ringing. The correct time for felling is just before pruning the tea so

that unavoidable damage can in part be rectified at the subsequent pruning. This system demands

forethought so that all these operations; ringing, felling and pruning of the tea, dovetail correctly into

one another in point of time. Probably the prejudice against shade, where that prejudice exists, arises

from unsatisfactory yields under old shade allowed to outlive its usefulness. Examples could be

quoted where total removal of shade has had an immediate beneficial effect on crop, for this reason,

but the benefit is short-lived. Accurate shade experiments are notoriously difficult to carry out

because so many interlinked factors are present.

19.1. Lopping and Uprooting of Shade Trees

Periodically the lopping of low shade trees is a very important practice to prevent too much

shade during the rainy periods. For the tree itself lopping is necessary in order to produce a

satisfactory recovery and adequate shade during the drier months. Only branches at the up end of the

stump should be encouraged to grow and all other shoots which are/below as well as those which

grow between the plucking table of the tea bushes should be removed with a sharp knife without

damaging the bark of the stump. A stripping of the branches by hand should be avoided because this

will damage the bark of the main trunk of the tree and finally retard the growth of the shade tree. The

35

thinning-out of large branches is necessary to prevent the tree from becoming top heavy and liable to

be blown down,

The most suitable time for lopping the branches is when they show maturity on the bark of the

stem and not, when the branches are green and tender. When lopped at this stage, recovery is

satisfactory even with a completely branched-out canopy. The shade trees in the up-country could

generally be lopped two times a year, in the low-country up to 3 times. Depending on the planting

district and annual variation of precipitation the first lopping in the Wet Zone could be done around

March/April and the second by the end of August, when the dry period is over. In the low-country a

third lopping can take place in November. For the districts in the Dry Zone lopping should be carried

out in October and partly in February, which depends on the precipitation quantity during the first

intermonsoonal period. In case of predictable small quantities of precipitation during the

above-mentioned period the crowns of the shade trees should not be lopped completely, then only a

thinning-out of the largest branches is recommended. The Loppings should be placed as green manure

and mulch between the rows of the tea plants, which will increase the soil fertility and reduce soil

erosion during the rainy period as well as evaporation during the dry spell.

When the time for lopping the shade trees has come, the topography as well as the exposition

of the tea fields should be taken into consideration: lopping should first of all start in the steep to very

steep westernly exposed tea lands and then in those of an eastern exposition. The trees should be

completely lopped in the westernly exposed fields, whereas a thinning-out of large crown branches

would be enough in easternly exposed fields. In the Wet Zone the first rainy period in the course of

the year is the first intermonsoon, which is characterized by sunny, cloudless mornings and by heavy

afternoon showers. After the sunrise the easternly exposed tea lands still get intensive sunlight and the

not fully lopped shade trees protect the tea bushes against sun-scorch and over-heating.

During the field rounds the author has observed that the westernly exposed steep to very steep

tea lands get full sunlight only around 11 a.m. or even later. When the diurnal temperature and the

convectional movement of air masses have reached their maximum around 2 p.m., heavy

intermonsoonal showers start. The sky is fully covered with clouds and no direct sunlight reaches the

tea bushes. Therefore a complete lopping of shade trees in the westernly exposed tea lands is

absolutely necessary with the onset of the first intermonsoonal season.

36

19.2. Uprooting

When the old tea bushes are uprooted prior to replanting, old stands of shade trees should also

be uprooted. The quickest and safest way to kill a shade tree completely is to ring-bark it. Thereby the

roots and shoot simultaneously die off and harbouring root diseases causes no trouble. The idea of

ring-barking is to deplete the food reserves in the root and the stump. To achieve this bark must be

removed over a length of 30 cm along the trunk at about chest height. The ring barking of trees like

Grevillea should commence two years before actual felling. It then takes eight months to two years to

die, the time for dying depending on the size of the tree. Dadaps and Gliricidias should be ring-barked

about 6-8 months before the actual removal of the trees is planned. The felling of the trees should be

done 2-3 months after all leaves have yellowed. Once a tree has been felled, it is advisable not to

allow a stump to remain above soil level. It should be cut to a point below soil level and covered with

earth.

20. The Bad Effects of Shade

To offset these undoubted good effects of shade there are various risks. Wherever there is

widespread fungus disease of tile leaves of tea the presence of shade is likely to prove a significant

factor encouraging its persistence India with the Blister blight a humid atmosphere in the vicinity of

the leaves encourages the quick germination or the disease spores. After their release the spores must

germinate and tile growing thread-like mycelium must penetrate into the leaf within a matter of a few

hours or it will die. Of the millions of spores that do fall on leaves, only the favoured few survive.

Sunlight is lethal to them and so is rapid drying of the leaf after rain and dew. Air movement and

evaporation are both decreased by shade, which accordingly reacts favourably on fungus infection.

Brown Blight (Colletotrichum camelliae) is common and enters the leaf through wounds such as are

caused by hail Once a fungus has established itself in the leaf, climatic conditions cease to have in

immediate effect on its chance of survival and as has been remarked earlier, shade by protecting the

foliage from a measure of laceration is a help rather than a hindrance in the prevention of this

particular disease.

Shade trees are always a potential source of infection by root diseases such as Armillaria, but

this risk is not very marked if shade trees are treated properly and are ringed before they have to be

remove competition for nutrients is not of great importance because, apart from what is locked up in

37

the permanent tree structure, the nutrients that the shade trees absorb are returned to tile soil and in tile

case of the leguminous species, there is a net nutrient gain nodule nodule-fixed nitrogen.

It is also possible to have shade. So dense that the optimum light intensity, even for shade

loving species, is not reached. When this occurs there is direct evidence of it in the drawing up of 'the

plant into sappy, and spindly growth, a reaction that is particularly deleterious to young tea and

probably the quality of manufactured tea from mature hushes in plucking (Eden, 1952).

20.1. Competition between shade trees and tea bushes

The fact of competition between the shade trees and the tea bushes has to be taken into

consideration. Different authors (Carr 1970, Domros 1974, Peters 1978, Kathiravetpillai 1985) have

pointed out that shade trees compete with the tea bushes in relation to nutrients, moisture, aeration,

and light. Especially Dadaps (Erythrina lithosperma) and Acacias are characterized by a very shallow

rooting system, extending a large area in the upper soil layers. During periods of moisture stress they

definitely compete with the tea bushes, which are also characterized by a lateral root system. This

moisture and nutrient competition will have its peak in sandy or gravelly soils. Therefore both species

should not be planted as shade trees in tea fields with sandy or gravelly soil texture. An introduction

of both species is only recommended in tea growing areas, which are not characterized by frequent

droughts. In the low country massive trees of the species Albizzia moluccana quite often to be seen

as shade trees in the tea fields. It is not advisable to plant them as shade trees because of the

above-mentioned reasons. These trees are also characterized by shallow, extensive root systems,

which definitely compete with the surrounding tea bushes during the time of water stress. The root

system of Grevillea robusta and Gliricidid maculata extends to deeper soil layers than tea roots,

which means that a competition is reduced to minimum during moisture stress. They can be planted in

all planting districts and soil types.

Shade trees should be planted in a wider spacing in such estates which are located in deep N-S

valleys. In the course of a day there are only a few hours of direct sunlight around noon for all tea

fields. A heavy stand of shade trees would decrease the duration and intensity of sunlight even further.

21. Role of shade trees in reducing wind damage

An important ecological factor in relation to the growing conditions and yield potential of a tea

plant is the wind. High speed of - surface winds causes mechanical damages to the bushes, especially

38

in the case of young plants. Mature tea bushes suffer under heavy winds because the immature young

shoots ("two leaves and a bud"), which are essential for tea manufacture, are stripped off, which

causes a loss of crop. Sometimes even smaller branches break or get blown off and a defoliated bush

remains. It takes a long time for a bush to recover from such damage.

Within the tea growing area of Bangladesh a spatial variations of wind Direction and velocity

play a major role with regard to the occurrence of damage. The present study mainly concentrates

upon wind conditions, which cause mechanical damage to the tea crop. The arriving winds of

southwest monsoonal origin are forced to raise and to cool down on the western and southwestern

slopes thereby cause orographic rains. The surface winds during this period of a velocity of

60-80 km/h or even more, cause severe mechanical damages to the cultivated tea crop on the

described windward side.

21.1. Planting materials and wind damage

The arriving strong winds are able to cause damages by blowing off tea leaves, but those are

not as severe as in the tea fields of a lower bush density. Fields with a low stand of tea bushes are

patchy and provide an increased surface for the attacking winds. This results in small-scale

turbulences between the bushes whose power is highly destructive and resulting in great damages.

Therefore the patches in the low-density fields of wind-swept areas have to be in filled with

vegetation of the same height as the tea bushes. Infilling tea bushes, of course, can be done in case of

high-yielding fields, which are expected to remain productive for the next 10 or 20 years. But in fields

which are due for uprooting in the next 5-10 years, the patches can be filled in planting Guatemala

grass. This will serve many purposes, such as the reduction of-the target for arriving destructive

winds, the protection of the fully exposed soil against soil erosion, the reduction of the evaporation

rate and soil temperature during dry weather conditions. Both species are easy to establish and grow

very fast, but they tend to over-grow the neighbouring tea bushes. In such cases the grass should be

cut to the ground level during the time of non-occurrence of destructive winds.

Taking the planting material into account, the result is that 38 % of the studied seedling tea

fields are damaged by strong winds. Especially the Assam-seedling bushes with their large leaf-size

are mainly damaged. Only 19 % of the fields planted with estate clones are characterized by a loss of

crop during the period of strong blowing, which again proves the vigor and hardiness of those clones

as well as their high stand per ha. 42 % of all the studied fields exclusively planted with BTRI clones

39

are damaged by destructive winds. 63% of them are located in the up-country, 29 1-4 in the

mid-country, and 8 % in low-country elevations. In the up-country the large-sized leaves of the TRI

clones are easily blown off with increasing wind speed. Due to a frequent occurrence of strong winds

and damage the bush gets weaker and weaker and recovery takes a longer time. This means a frequent

loss of crop of tea bushes which are expected to be high-yielding, which are responsible for the

continuous decline of the productivity of Bangladesh Tea Industry. Shade trees reduce the wind

velocity and protect the tea bushes from drastic damages.

Figure 3: Wind damaged tea bush

21.2. Shade trees as shelterbelt

Shade trees can act as shelterbelt and protects the tea plantation from wind damage.

Shelterbelts are strips of vegetation consisting of a mixture of trees and shrubs with the aim of

protecting valuable lea land and crop from destructive winds. Shelterbelts, consisting of several lines

of trees and shrubs, reduce the wind velocity on both sides, which results in a decreased destruction of

the tea bushes and increases the yield of the protected fields. Their effect can be felt at 15 times the

height of the belt in the lee and at about three times the height of the belt on the windward side. A

reduction of the wind speed on both sides of a shelterbelt is combined with a minimization of wind

erosion on the soil surface. In steep areas shelterbelts with their dense vegetation act as buffer strips

intercepting surface run-off and reducing water erosion. An improvement of the micro-climate can

also be achieved by reducing the evapotranspiration rate in the neighbouring tea lands during a dry

spell. Due to the existence of such-shelterbelts the population of birds that frequent tea fields and prey

on swarming termites increases. The appearance of the landscape is improved by interrupting the

40

monotony of the tea bush carpet. The value of a shelterbelt is the higher, the more tea lands it protects.

It can be expected that the loss of productive area will be more than compensated by their benefits.

A mixture of medium to tall trees in the centre and of small trees and shrubs on the outside of

the belt is most effective. Shelterbelts have to be dense in their lower part, whereas the middle and

upper parts should be more open. A completely impermeable wind barrier is aerodynamically

disadvantageous because it would cause whirlwinds in the lee and eliminate the protective function.

Shelterbelts may consist of several rows of trees or shrubs planted at a right angle to the direction of

the prevailing winds. It is also possible to allow tea rows inbetween to grow freely. The interval

between the shelterbelts, where high wind velocities are to be expected, should be about 100 m, in

case of less severe occurrences about 200-300 m (BTRI recommendations). A shelterbelt should

consist of approximately 65 %. Shrubs and 35 % trees which should further be subdivided into about

15 % tall and 20 % medium sized trees (BTRI recommendations). Large trees are to be planted in

small clusters, small trees and shrubs in larger groups.

Figure 4: Acacia auriculiformis is used as wind break at Kamaichora Tea Estate

41

Grevillea robusta and Albizzia moluccana are suggested to be tall trees for shelterbelts. For the

medium elevated areas: Grevillea robusta, Albizzia moluccana, and Gliricidia maculata. Again, the

fact of competition between the shelterbelt trees and the tea bushes has to be taken into consideration.

Especially Albizzias Dadaps and Acacias with their very shallow rooting system should not be

integrated as windbreaks in sandy or gravelly tea fields.

22. Importance of shade trees at a glance

Drought resistance

Reduce the rate of evaporation of the soil moisture

Reduce wind velocity. Shade trees act as wind break in tea garden

Prevent the tea plant from direct sunlight and reduce the light intensity (50-60%

diffused sunlight)

Reduce the temperature of the garden

Increase nutrient by litters and leaf falls

Increase nitrogen supply in the soil

Reduce soil erosion

Provide situation for proper photosynthesis

Essential for modulating the environment of tea ecosystem

Also product fuel wood and timber for our national consumption.

23. Uses of Shade trees

Shade trees, other than providing shade to the tea gardens are also used for diverse purposes

when they are matured and harvested from the tea estates.

Furniture: A. odoratissima, A. chinensis, A. procera, Dalbergia sissoo, A. falcataria, A.

lebbeck

Panelling: A. lebbeck, A. chinensis, A. odoratissima, A. falcataria, A. Procera, Albizzia

moluccana

Agricultural implements: A. procera

Fodder: Animal feeds are in short supply in many parts of the tropics. Leaves or pods from

fodder trees are an important source of animal feed, particularly in area such as South Asia. Fodder

trees are generally either browsed by the animals directly or the fodder is cut and carried to animals,

which are confined or tethered. Trees which are used as fodder sources in tea estates management

42

include Gliricidia sepium, Leucaena leucocephala, Acacia albida, Acacia senegal, A. Chinensis, A.

Lebbeck, A. Procera, Erythrina lithosperma, Cajanus cajun.

Food: Food for human consumption is often an important output from shade trees. Pods, seeds

young leaves and flowers are the most common sources of human food from NFT. Outstanding

expamples of NFT as tree foods are Sesbania grandiflora and Gliricidia sepium (flowers), Leucaena

leucocephala (young shoots, pods and seeds), and Erythrina flowers.

Timber: A. lebbeck, A. chinensis, A. procera, A. lebbeck

Charcoal: A. lebbeck, A. procera, A. falcataria

Posts, Piles: A. lebbeck, A. chinensis

Planking: A. falcataria

Pulp and paper: A. falcataria

Gum/Tannin: A. chinensis, A. lebbeck

Fuel wood: A falcataria, A. chinensis, A. lebbeck, Acacia auriculiformis, Acacia mangium,

Leucaenas, Dalbergia sissoo, Grevilliea robusta, Albizia lucida, Derris robusta.

Pulp wood: A. falcataria (excellent for fibre and particle board also used as veneer core stock

and crafting)

Matches and boxes: A. falcataria

Veneers: Dalbergia sissoo, (also used for structural works, cart wheel, railway carriage, boat,

ploughs, toys, tenis rackets, hocky sticks, musical instruments making etc) A. falcataria.

Carved articles: Dalbergia sissoo, A. falcataria

Resin: A. auriculiformis,

Fertilizer: Leguminous shades are often having the advantage of high nitrogen foliage, which

can be used as a green manure to fertilize other crops. Farmers in some areas have long recognized

that crops grow more productively under some trees than they do under others. NFT, which produce

succulent, high-nitrogen foliage and have the ability to regenerate from coppice shoots are excellent

sources of nutrients.

43

Tea chests: Bangladesh needs nearly 9 lakh of tea chests per year for exporting tea in the

foreign market. The supply of the entire quantity of chests is met by the local factories. The

“Bangladesh Standards for tea chests and plywood for tea chests 18:1978” recommend 36 species for

the manufacture of shooks and battens. Some of the species are susceptible to fungi and require

prophylactic preservative treatment with borax, boric acid or zinc chloride (Anon. 1978). Soft to

moderately hard species are required for tea chests; the figure of the wood is of least importance.

Flavour of the tea is an important consideration. The tea chests, therefore, be manufactured with wood

species free from any inherent undesirable odour and must not offer any taint to tea subsequently. A

few shade tree species can be used for making effective chests for packing tea. These are Albizzia

moluccana, Albizzia falcataria, Dalbergia sissoo etc. (Azizullah, M.A. 1982).

Figure 5: Packaging of tea in the tea chests is going on

44

24. A grief description of two important shade trees used in Bangladesh tea estates

24.1. Gliricidia Sepium As A Shade Tree

In recent years, many tea estates have witnessed deterioration in their stands of shade trees.

This has been most marked in the case of pure stands of Chakua koroi (Albizzia chinensis) which on

some gardens have been completely destroyed as a result of cankers caused mostly by the attacks of

'the Buprestid, Agrilus beesonii, but in the, sada koroi (Albizzia procera) is also dying out due to

attack by Orange Mite. The rapidity with which the existing shade trees have died has called for an

equally rapid replacement by new ones and it is for this reason that fast growing species such as

Gliricidia sepium (previously Gliricidia maculata) are being planted on an increasingly extensive

scale.

Figure 6: Gliricidia sepium which is used as temporary shade tree in the tea plantation

Gliricidia sepium was introduced into Bangladeshfrom the West Indies as an ornamental

flowering tree. It grows quickly producing long arching branches carrying abundant foliage. Leaves

45

are shed during the cold weather and the tree remains leafless until after it has flowered in

March-April.

The seed matures in May-June, but should only be collected from mature trees because the

seed set in the first few seasons is of very poor quality. Trees can be raised from seed in nurseries in

the normal manner and transplanted with a bheti in the following February-March, but excellent

results have also been obtained by putting it out as seed at stake on several estates. Alternatively,

Gilricidia sepium can readily be propagated from cuttings. The cuttings should be made from 2-year

old wood and should be ¾” -1" in diameter at the base and 5-6 ft. long. They should be set directly in

their final positions 9"-12" inch deep and made very firm. Shading is the natural canopy of the tree is

inconveniently low and the lower branches must therefore be lopped periodically. Even when a high

canopy has been formed, some thinning of the crown is needed from time to time to prevent it from

becoming too dense. The tree responds well to lopping and the mass of green material obtained is

valuable as mulch.

The use of Gliricidia sepium is not limited by soil type as it flourishes on heavy clay as well as

sandy soils. To date, the mature trees have proved free from serious pests or diseases. The scale insect

Ferrisia virgata is the most notable. A good solution is Clensel, a liquid soap, diluted to 1 in 30 parts

of water. The addition of I oz. of Dieldrex 18% E.C. per 10 gallons of spray fluid is likely to increase

the effectiveness of the application. It is important that spraying should be carried out in bright sunny

weather and a second round given if necessary.

Gliricidia sepium does not develop into a large permanent shade tree, but with systematic

lopping it .should have a useful life of up to 20 years. It can most usefully be employed by

interplanting between young permanent shade trees. Thus in permanent shade, planted 40 ft. X 40 ft.

square, a Gliricidia sepium tree should be established in the centre of each 40' X 40' square. It is

advisable to plant the trees between the rows of tea rather than to uproot a tea bush. This procedure is

equally suitable when establishing shade in young tea or replacing shade in mature tea. In both cases

the Gliricidia sepium serves the useful function of providing shade for the tea during the period when

the young permanent shade trees are largely ineffective. On tea estates in Assam, it is usual to uproot

Gliricidia sepium when the permanent shade trees have developed sufficiently. This practice contrasts

with that followed in Southern India and Ceylon where this shade tree can commonly be seen growing

beneath mature stands of Grevillea robusta or Albizzia species. In this case Gliricidia sepium is

46

retained for the value of its loppings rather than its shade. The trees are pollarded and lopped heavily

four times in a season, thus providing a mass of green manure for the tea. The trees are uprooted and

replaced by new cuttings when necessary.

25. Leucaenas as shade trees

Leucaenas are seen as ideal trees for agroforestry, shade tree in the tea plantation contributing

to overall productivity and helping to stabilize and enrich the soil fixing N2 in it.

The Spanish sailing ships of four centuries ago brought the first leucaenas from Mexico to

Asia. In the nineteenth century, leucaenas spread widely in Asia and the Pacific region, throughout

Latin America and later in Africa. They were used as shade trees for coffee and tea and became

increasingly important as a source of fuelwood because they grow back easily after coppicing. Today,

farmers grow leucaenas on an estimated 2 million hectares, in every tropical region of the world.

There are 13 species of the genus Leucaena in the great family legumes. These are native trees of the

America. The most common species is Leucanea leucocephala, the white-headed leucaena). The

'giant' leucaenas are single stemmed trees, growing up to 20 metres high and 50 centimetres in

diameter. In ideal conditions, they grow more than 10 metres in three years, reaching their maximum

height in about eight years. The wood is dense-a ‘medium hard-wood’ of 0.6 specific gravity. It works

well for carpentry, maturing to a pale brown, and can make good flooring. Burning properties are

excellent: farmers almost everywhere use leucaenas for home fuelwood. Charcoal made from leu-

caena also has good properties. Leucaena wood has-even been used on an experimental basis to fuel

large-scale electric power plants. They grow quickly during the rainy seasons and can survive long

drought. While they grow bestinareasw re annual rainfall is more than 1000 millimetres, they can

survive, once well established, with annual rainfall as low as 500 millimetres.

They can survive fire and frost’ by growing back from the undamaged crown, and can

withstand severe annual grazing. When mature trees are coppiced, they can regrow from 4 to 6 metres

in one year. Farm families often harvest them by coppicing every year. Leucaena polewood is used in

house construction and for fences. It takes preservatives well; but has low resistance to wood-boring

insects). Perhaps leucaena's most important feature is its ability to enhance soil fertility by fixing

nitrogen. Atmospheric nitrogen is converted into useful compounds in small nodules on the tree's i

outs; that are inhabited by symbiotic bacteria known as rhizobia. The tree builds these compounds

47

further into amino acids, proteins and other substances, resulting in leaves rich in nitrogen and other

minerals.

Farmers in Southeast Asia have exploited these 'living nitrogen factories' for decades by

interplanting leucaenas in their maize fields. Before the maize is planted, the trees are cut low and

branches are spread on the ground to provide leaves as fertilizer. Fodder from leucaena and other le-

gumes is rich in protein, representing the organic form of fixed nitrogen. Leucaeua can provide an

important protein supplement for ruminant livestock, such as cattle and goats. Leucaena

trees-particularly certain hybrids-can produce gum exudates that are similar to gum Arabic.The seeds

also contain a pure galactomannan gum that may have useful pharmacological properties. Leucaena

leaves are taken as medicine in some countries to settle the stomach and for other less plausible cures.

Leucaena is easily propagated, although methods vary in different parts of the world. Seeds

germinate readily. Lucaena seeds are 'hard', with a tough seedcoat that excludes water. To promote

germination, the coat can be cracked or scarified by various treatments: the simplest is to nick the seed

with a knife. One effective treatment involves pouring boiling water over the seeds and pouring it off

after three to five minutes. Following any of these treatments, the seeds can be soaked overnight,

easily revealing those fattened ones that are likely to germinate. The common leucaenas (L.

leucocephala) have small white flowers in tight clusters, with little odour. Other leucaena species

have red or yellow flowers, often with a strong odour that is attractive to bees. All leucaenas have

long thin seed pods with straight edges that hang straight down and turn brown as they ripen, which

takes about three months. The bark is thin and need not be removed for piper of rayon production.

Several less common species are-

L. diversifolia: this is a red-flowered highland tree with tiny leaflets, flowers, pods and seeds;

not weedy; good psyllid resistance

L. pallida: trees are pink-flowered with leaflets, pods and seeds like L. leucocephala; tolerant

of cold; bushy or arboreal; psyflid resistant

L. pulverulenta: this species is characterized by small white flowers on a very large tree with

grayish young leaves and tiny leaflets; it is tolerant of cold

48

L. salvadorensis: a white-flowered tall tree with small leaves; good pole wood; suitable for

lowlands.

25.1. Some information about Ipil-ipil (Leucaena leucocephala), a common leucaena, which is used as shade tree in the tea estate is given here;

Climatic Conditions: It grows best in full sunlight and in high light 'Intensities but its growth

is relatively slow when in heavy shade. The tolerable length of dry season is 5-6 months. The annual

mean temperature range from 14.7o C - 27.4o C. Frost kills it. Annual rainfall requirement is 100 -

3000 mm)

Physiographic, Edaphic and Biotic requirements: Ipil-ipil prefers neutral to

alkaline/limestone soils. It could tolerate rocky sites with little soil, although the growth is slow and

height often stunted. It grows poorly in acidic soil with pH below 5.5 and in water-logged areas where

the soil has deposits of Al, Fe, or silica). It can tolerate sandy clay loam to sandy loam soil with pH

ranging from 5.6 to 8.0. It thrives in elevation less than 700 meters above sea level.

Phenology: On areas where moisture is available, leaf shedding is very minimal. In drier

areas, however, almost complete leaf shedding occur during the hottest portions of the year. Leaf

flushing occur two weeks after the first rain.

Silvicultural Characteristics: This species is very light demanding. It grows best in full

sunlight and in high light intensities. It is one of the fastest growing trees in the tropics.

Planting in the tea gardens: This species can be established by planting nursery grown

seedlings or by directly sowing pretreated seeds in the field. It can also be grown by rooted cuttings

and grafts (Zabala, 1977). It is planted at a spacing of 6 m x 6m with tea bushes.

Silvicultural systems: This species is a very popular multi-purpose tree. Its uses are firewood,

charcoal, source of electricity, fodder, pulpwood, medicinal, posts, tannin, banana props, organic

fertilizer, soil improver, firebreaks, shade and nurse crops, ornamental, erosion control, etc.

49

26. Influence of Shade on the Incidence of Pests in Tea Plantation in Bangladesh

The use of the leguminous and few non-leguminous trees as shade for tea is common in the tea

growing areas of the world but there are some exceptions depending upon topography and

agro-climatic conditions. Tea ecosystem generally comprises tea, shade trees, green crops, forest, etc.

The intensive monoculture of a perennial crop like tea in Bangladesh over an extensive land area in

Sylhet, Chittagong and Chittagong Hill tracts has virtually formed a stable ecosystem for divergent

pests and diseases. In Bangladesh, so far 29 arthropod pests including insects and mites, 1 algal and

18 fungal disease are recorded (Sana 1983, Ali 1990). Due to their infestation over the years,

inadequate shade, poor drainage, improper intercultural practices etc., the annual crop losses is

estimated to be about 10-15% (Ali 1990))

There is some controversy over use of shade but it is fairly certain that the shade trees are

essential for modulating the environment of tea ecosystem, enriching the soil fertility, reducing

temperature and the evaporative capacity, conserve soil moisture and helps in the control of certain

pests and diseases which are positively thermo tropic in nature (Eden 1952, Barua 1989). On the

contrary, shade trees also serve as potential source of root diseases, encourages -quick germination of

disease spore, invite and harbour different insect pests as well as play a vital role for the transmission

and transmigration of pests and diseases among different components of tea ecosystem (Hasan 1963).

In spite of that the importance of shade in the plantations in Bangladesh as far as pest infestation is

concerned can not be over emphasized.

To evaluate its influence, a reconnaissance pest survey was undertaken at Baraoorah Tea

Estate where deshading was practised by the management. During the study as many as nine pests and

diseases invaded successively at different times during cropping season. It also envisaged that the

incidence of most of the pests spectrum were found comparatively higher in unshaded than shaded

area indicating direct influence of shade on pests. This study also confirms that shade in plantations

plays a certain beneficial role in regulating pests incidence. From the study, it would appear that the

seasonal incidence of Termites, Jessid, Flush worm, Macrophoma were prevalent throughout the

period and were more pronounced in the unshaded than shaded plantations due to their sun loving

habit. Activity of Termite and Macrophoma, which are considered t be recurring problem, were more

or less acute irrespective of shaded condition.

50

Helopeltis being a negatively thermo-and phototropic appeared comparatively higher in the

shaded than the unshaded condition. On the contrary, red spider mite, Red rust were seen during the

early part of the cropping season and thereafter through its incidence declined, mild to moderate

infestation of Red spider mite was prevalent during mid cropping season.

The study also reflected that the overall incidence of most pests and diseases were more or less

consistent in different quarters but their magnitudes of attack were comparatively higher in unshaded

areas. The initial attack of the recurrent pest was slight to moderate during the first quarter which

becomes dominant during the second and third quarters. Infestation of permanent pest like Termite,

Macrophoma and seasonal pest like Helopeltis and Jassid were pronounced during the fourth quarter.

This directly indicated the influence of shade on the colonization, perpetuation and succession as well

as status of pests in different ecological niches.

Of all standard control strategy, shade management no doubt plays a significant role to

minimise pest problem to a great extent. From this observation it is quite apparent that the importance

of shade cannot be over emphasized t check tea pest by providing optimum shade condition through

planting of leguminous shade species.

27. Diseases of Shade Trees

Shade is an important and' necessary component for plantations. They are however, very often

attacked by various diseases which if not controlled may result in reduction or elimination, of shade

and consequent susceptibility of the tea underneath secondary and weak parasites. Some of the shade

tree disease organisms are vigorous parasites of the tea plant itself, and if left uncontrolled may attack

the adjoining tea. In the paper an attempt has been made to put together all available information on

the occurrence, disease symptoms, host spectrum and control measures as applicable in Bangladesh.

27.1. Leaf diseases

The fungi causing leaf disease may be grouped as follows:

I) black rot, II) rusts, III) Camptomeris leaf V) spot, IV) Sooty mould and Aschersonia, V)

Cercospora leaf spot, and VI) uncommon fungi. Of these, only black rot is an important disease of

tea.

51

I) Black rot as in tea, the disease is caused by both Corticium invisum Petch and C. theas

Bernard and the symptoms produced on the hosts are almost identical. The fungi produce patches

causing a part or entire leaf/leaflet to wither away. The affected leaves/leaflets remain suspended or

attached to the stems or other leaves by means of the fungal mycelium as in tea. The fungi spread by

contact and grow rapidly in cool humid, dull wet weather during July-August. The affected leaves

drop off and transmit the disease to, tea underneath. Fortunately such cases are rare and the disease

has been recorded mostly in the nursery plants.

Host spectrum: Albizzia amara Boiv., A. Chinensts (Qsbeck) Merr., A. falcata Baker Syn A.

moluccana Miq., A. lebbek Benth. A. odoratissinta Benth., A. procera Benth,, Alfurijis sp., Erythrina

sp., Gliricidia sepium (Jacq.) Steud,. Indigofem teysmanii Miq. (1960).

Thorough spraying of two rounds of copper fungicide at' fortnightly interval during the

actively growing season controls the disease.

Another fungus, Pellicularia filamentosa (Pat.) Rogers produces black rot like symptoms in

Albizzia falcala; the affected branches however die back following defoliation. In cross inoculation

studies identical symptoms were recorded in Gliricidia sepium while in tea discretenecrotic spots on

older leaves were produced(4). Excision of the dead portion to clean healthy wood and 2-3 rounds of

spraying with a copper fungicide at 14, day. intervel are suggested.

II) Rusts: Species belonging to the genera Ravelelia Sphaerophragmium and Uromyces have

been observed to cause disease spots in a few hosts, during the cold season. Ravenelia clemensae

Sydow, R. sessilis Berk. on leaves of Albizzia lebbek and A. procera (Ann. Rep. 1956), and another R.

sp. on A. chinensis (1968). Sphaerophragmium acaciae (Cooke) Magn, on A. odoratissima (1967).

Uromyces achorus Sydow: This brown rust was in association with a hyperparasite Darluca filum

(Biv Bern ex Fr.) Cast. on Dalbergia sp. (Anti. Rep. 1957).

The depredation by the rusts occurs towards the ends of the season when the leaves are due for

shedding.

III) Camptomeris leaf spots are caused by two species of Camptomeris on Albizzias (5).

52

a) Camptomeris albizziae (Petch) Mason. The disease manifests itself on the undersurface of

the leaflets as numerous, black pulverulent dots, reminiscent of rust: sori. The spots on the upper

surface are ill defined,

Hosts: Albizzia amara,_A. chinensis, A.falcata, A. gam. bleli Prain (1967). A. julibrissin

Durazz, A. Iebbek, A. odoratissima, A. procera.

The host A. gamblei was recorded in 1967 the others were reported earlier (5).

b) C. albizziicola (Thirumalachar and Narasinihain), Bessey. Spots produced are not much

different fro1w those produced by C. albizziae, the difference lies in themicroscor) in details.

Hosts. : A. lebbek (5)

No treatment is called for as the infection period concides with natural leaf fall.

IV) Sooty moulds and Aschersonia are fungi growing in honeydew secretion of scale insects

and on the insect respectively.

a) Sooty moulds: Many fungi including species of Meliola growing on honey dew secretion

as a superficial layer on the upper surface present a sooty appearance on the leaf. The coating breaks

off in flakes when dry.

Sooty mould was recorded on Derris robusta Benth, (1928) imol Meliola albizziae Hansford

et Deighton on .A. odoratissima (6).

b) Aschersonia sp. parasitizes scale insects and is seen as orange to pinkish red lump3 or about

1-2 mn diameter on leaves or stem.

Hosts : A. odoratissima, Derris robusta (1932). V) Cercospora leaf spot: More than two

species are involved.

Cercospora leysmanii Barua and Barua (7) attacks leaves of Indigofera teysmanii and

produces sub-circular to irregular spots on both the surfaces of the leaflet. They are brown with

greyish centre on the upper surface and brown to olivaceous brown on the lower surface. Adjacent

spots merge to form a bigger patch and in extreme cases the lamina may be distorted. Cercospora

subsessilis N. & P. Sydow produces spots on Melia azedakaeh Linn. (Ann. Rep. 1957) while an

53

undetermined species of Cercospora is recorded on Erythrina indica Lam (1957). Chemotherapy is

not advocated and none of the above Cercospora are found to parasitise on tea.

VI) Uncommon fungi: Some fungi are found to cause localised spots on certain species of shade trees

on few occasions. They are listed hereunder:

a) Periconia sp. on Erythrina indica (1957) and on indigofera teysmanii associated with

blackening of inflorescence axis (Ann. Rep. 1962).

b) Epicoccum sp. on Erythrina indica (1957).

c) Phyllochorca dalbergiae Niessl causing tar spots on -Dalbergia sissoo Roxb. (8).

d) Stigmella sp. on Erythrina indica (1957).

e) Stigmina sp. on Derris robusta (1956).

f) Phyllostica sp. on Erythrina indica (1957).

g) Stigmochora albizziae (Syd.) Arx on Albizzia odoratissima (1974).

27.2. Stem diseases

The diseases so far recorded are

I) Red rust, II) Nectria, III) Pink disease, IV) Macrophoma theicola, V) Phomopsis sp., VI)

Auricularia auricula, VII) Hypoxylon spp. and VIII) Uncommon fungi.

I) Red rust: This algal disease is of common occurrence in almost all the shade tree species

but the degree of incidence varies from species to species-Albizzia chinensis being the worst affected.

In badly attacked plants, the affected branches die back and always bear patches of orange-red

fructifications of red rust during April-July.

Hosts: Acacia lenticularis Buch-Ham. Adenanthere pavanina Linn. Albizzia amara (Ann. Rep.

1962), A. chinensis, A. gummifera J. F. Gmel (Ann. Rep. 1962), A. julibrissin (1960), A. lebbek, A.

lucida Benth (Ann. Rep. 1965), A. odoratissima, A. procera, A. sumatrana, Dalbergia assamica

Benth, Derris robusta, Gliricidia sepium, Indigofera dosua Buch-Ham, I. teysmanii, Melia azedarach,

Milletia dura Dunn (Ann. Rep. 1962), Parkia javonica.

As in tea, copper fungicides are effective in controlling the disease. Besides, improvement in

drainage and nutrient status of the soil reduces the disease.

54

Physolinum monile (De Willd) Printz is an epiphytic alga growing on shade tree trunks, often

confused with the red rust alga Cephaleuros parasiticus Karst.

II) Nectria spp. More than two species of this genus have been found to occur as wound

parasites of shade trees. They usually cause local infection but, at times, branches may die-back from

the seat of infection. They may be covered by white to pinkish soft cushions of the imperfect stage

and/or small globular, cinnabar to crimson red bodies of the perfect stage of the fungus. Tunstall (9).

has recorded how Nectria spread onto the tea in the direction of the wind from affected, Erythrina

plants. Their host spectra are recorded as follows:

N. haematococca Berk. et Br. on A. falcata (1957), A. odoratissima (1960), A. procera (1959),

Derris robusta (1958), Erythrina sp. (1919).

N. cinnabarina (Tode ex Fr.) Fr. on A. procera (1932) Dalbergia assamica (1933).

Nectria sp. on Albizzia falcata (1915), A. procera (Ann. Rep. 1956), Derris robusta (1925),

Indigofera dosua (1917) on roots and I. loava (1917).

Affected branches should be cut to clean healthy wood and sprayed with a copper fungicide.

Tea in such areas should be pruned between mid November and December. In case of hail damage

such tea areas should be thoroughly sprayed within 24 hours of the damage.

III) Pink disease (Corticium Salmonicolor Berk. & Br. Pellicularia salmonicolor (Berk. et

Br.) Dastur. It can be recognized as a thin film of silky white mycelium on the affected part of the

stem. The infection presumably occurs through the lenticels and leaf scars during the rainy season.

The fungus at first produces small whitish patches which later on increase in diameter assuming a pale

pink colour and gradually girdle the stem(4), though usually the trust is formed on the, shaded side of

the stem. The disease is known to attack young tea plants on rare occasions (3).

Hosts : A. falcata (Ann. Rep. 1961), Derris robusta (1926), Gliricidia sepium (1965).

The affected part should be cut to clean healthy wood and the plants be sprayed with a copper

fungicide.

55

IV) Macrophoma theicola Petch: The fungus causes branch die-back. Diseased patches on

the branches are noticeable as slightly sunken, usually longitudinal lesions, edged by a ring of callus

growth. The patches bear tiny, black, fruit bodies of the fungus during the rains. It also attacks tea.

The fungus is considered secondary to drought and sun-scroch damage and hence cutting out

of the affected portion to clean healthy wood is sufficient.

Hosts: A. falcata, A. odoratissima, A. procera, Dalbergia assamica and Milletia dura.

V) Phomopsis sp.: The fungus is found to cause branch die-back in few instances. The

affected region becomes sunken and turns grayish black or dark purple and becomes dotted with

minute pycnidial structures. Sometimes the wood tissue becomes permeated by bluish black lines. P.

theae attacking tea is different from the one known in shade, the latter in some instances has been

found to be associated with Valsa, Valsella and Eutypella (Ann. Rep. 1962) and also Phoma (Ann.

Rep. 1961).

Hosts: A. falcata (1932), A. richardiana king and Prain (Ann. Rep. 1957), Derris robusta

(1968), Gliricidia sepium (1957).

The dead portion is to be cut to clean healthy-wood.

VI) Auricularia auricular (Hooke) Underwood. The fungus attacks through wounds on

branches. It has also been recorded in tea as weak wound parasite of rare occurance (3). The disease

can be recognized by the soft, flesh coloured, gelatinous human ear-like structures borne on the

branches during rains.

Hosts: Albizzia procera (1929), Derris robusta (1926), Gliricidia sepium (Ann. Rep. 1957).

Diseased branches should be lopped to clean healthy wood.

VII) Hypoxylon spp.: Four distinct species of the genus including the one causing Tarry root

rot in the tea have been recorded in shade tree branches and discussed by Agnihothrudu (10). The

fungi produce spores in flattened, hard, almost black encrustations, the upper surface of which is

smooth, and even, resembling dried black paint.

56

a) H. stygium (Lev.) Sacc. When young the spore bearing stroma is a thin reddish brown layer,

later on this turns red and with the production of perithecia deep purplish black. It is very often

found on Gliricidia sepium.

b) H. bovei Speg. (Var microspora ?) Miller. Here stroma is restricted or rarely somewhat flat

with abrupt margin. It has been recorded on two undetermined twigs of Albizzia spp.

c) H. truncatum (Schw. ex Fr.) Miller. When young the stroma is greenish, and then it gradually

turns brown becoming black with development of perithecia. Stroma 2-3 mm thick with

perithecial projections. The fungus is recorded from one dead branch of Albizzia sp.

d) H. nummularium Bull. ex. Fr. var merillii (Bres.) Miller. The fungus causing Tarry root rot of

tea, II. asarcodes (Theiss) Mill. is considered as its synonym. Agnihothrudu (II) considers H.

asarcodes as a stem parasite. The stroma in shade tree is exposed, flat, deep purplish to almost

black and typically sub convex.

The disease has been almost confined to the tea growing areas of West Bengal.

Host: A. procera.

Cutting out of the affected parts is considered sufficient except in the case of the case of the

last named species where care should be exercised not to spread the diseased material on to the tea

underneath.

VII) Uncommon fungi: Some fungi have been recorded in some shade tree species on

isolated occasions. They are as follows:

a) Kutilakesopsis macalpinae Agnihothrudu et GCS Barua (12) is isolated from stem pieces

of A. richardiana. The fungus produces cushion shaped esslle sporodochia at first white,

then turning pale olive green with age. An identical fungus was also recorded on dead

twigs of A. procera in 1956.

b) Haplosporella aleuritis Agmojptjrudu, Hadfield (13) is reported from dead snags and bark

of Aearitis Montana Wilson as possibly responsible for the die back.

57

c) Exosporium assamicum Agnihothrudu (14). The fungus is recorded from dead branches of

Albizzia chinensis.

d) Sporidesmium tropicale M.B. Ellis. This dematiaceous hyphomycete is very common on

dead twigs of shade trees particularly those of A. chinensis (14).

e) Daldnia concentrica (Bolt. ex Fr.) Ces. & de Not. is recorded on dead twigs of Derris

robusta (Ann. Rep. 1957).

f) Cytospora sp. on Albizzia richardiana (Ann. Rep. 1957).

27.3. Root diseases

Some shade trees are killed in the nursery by- I) Pythium sp. II) Fusarium sp. III) Rhizoctonia

sp. and IV) bacterial wilt while in the field condition after being planted out many are attacked by V)

primary root disease VI) secondary root disease and VII) uncommon diseases. They are discussed

hereunder.

I) Pythium sp. The fungus causes ‘damping off’ in very young plants during rains when the

diseased plant suddenly dies out during a period of hot dry weather following wet spells. The bark of

the affected root decays and peels off easily, specially at the collar region below the soil surface.

Hosts: Albizzia procera (1946), A. sumatrana (1957). To avoid this particular fungus crust

formation in nursery beds in heavy soil should be avoided. Cheshunt compound or a copper fungicide

is advised to treat the survivors after removing the dead ones.

II) Fusarium sp. It attacks during the rainy season when the collar region along with the

surface roots become covered with a thin, white fungal growth. In many cases tissues inside turn

black.

Hosts: A. chinensis (1948), A. falcata (Ann. Rep. 1956), A. richardiana (Ann. Rep. 1960),

Derris robusta (1929), Gliricidia sepium (Ann. Rep. 1956), I. teysmanii (Ann. Rep. 1963) and on D.

robusta (1934) as Fusarium udum Butler.

III) Rhizoctonia sp. Two species have been recorded. The collar region is the worst affected.

It becomes covered with white fungal mycelium browning slightly with age. Sometimes sclerotia are

also recorded.

58

Rhizoctonia solani Kühn is found to kill. A. odoratissima (Ann. Rep. 1960) and I. teysmanii

(Ann. Rep. 1963) seedlings whereas one undetermined species of Rhizoctonia killed seedlings of A.

richardiana (Ann. Rep. 1960).

IV) Bacterial wilt: This is recorded in Gliricidia sepium seedlings (1955) in the nurscries.

The affected collar region presents a water soaked appearance. In the case of the above three diseases,

the affected plants are to be pulled out together with a couple of unaffected ones from either side and

destroyed. Planting of susceptible trees are to be avoided.

V) Primary root diseases: They can directly attack and kill a shade tree and sometimes its

surrounding tea bushes in such a way that it would appear to have been killed by lighting. In

lightening however the accompanying dead tea bushes would always be more than nine in number. A

part or the whole of a tree may die suddenly. The primary root diseases of tea attacking shade trees

are:

a) Charcoal stump rot, b) Brown root rot, c) Black root rot, d) Purple root rot and e) Tarry root

rot.

a) Charcoal stump rot: Ustulina zonata (Lev.) Sacc. = U. deusta (Fr.) Petrak. The disease

produces at the collar region, characteristic wavy incrustation which is white at first, turning grey and

finally charcoal black; in course of about two weeks time it becomes hard and brittle. Silky fan-like

mycelium abounds on the surface of the wood and can be seen when the bark of a diseased root is

removed. The root tissues become permeated by irregular black lines or bands.

Hosts: Albizzia chinensis, A. falcate, A. odoratissima, A. procera, Aleuritis montana, Derris

robusta.

b) Brown root rot: Fomes lamaoensis (Murr.) Sacc. and Trott. = F. noxius Corner. The

diseased root is characterized by an encrustation of soil, sand and stone particles held together by

brown mycelium. The root surface may be interspersed by cushions of brown mycelia. The affected

roots bear brown lines or reticulations.

Hosts: Albizzia chinensis, A. odoratissima, A. procera, Dalbergia sissoo, Derris robusta,

Erythina spp. and Melia azedarach.

59

Black root rot: Rosellinia arcuata Petch and R. bunodes: (Berk & Br.) Sacc. The affected

plants some times bear wooly, purplish grey to black stocking of mycelium at the collar region going

up the stem. On the root surface black, irregular, cob webby mycelial cords and black isolated spots

are seen. On removing the bark small white to black star like markings are seen with black dots and

dashes, the last two are also seen when a cut is made into the wood. Perithecia are seen produced as

almost black spherical bodies at the collar region.

Hosts: A. procera, Erythina sp. and Indigofera dostia.

d) Purple root rot: Helicobasidium compactum Boedijn: The disease develops its

fructification as a thick velvety mycelial pad at the soil level often girdling the whole stem for several

centimeters. The colour of the growth is purplish to state chocolate while that of the affected wood is

pinkish.

Hosts: A. chinensis, A. odoratissima (Ann. Rep. 1965), A. procera, Gliricidia sepium (Ann.

Rep. 1965).

e) Tarry root rot: It attacks A. procera and has been discussed under stem diseases (VII d)

Meticulous removal of all the dead roots from the soil is the most common method advocated

in dealing with primary root diseases. Tunstall (15) records an outbreak of brown root rot in tea traced

to a piece of Mesua ferrea root lying buried at 120 cm. depths for at least fourteen years. Ring barking

(16) is recommended to avoid storage promote depletion of starch in the roots of trees due for felling.

Lightening affected tree is to be removed at the earliest as it is likely to be attacked by Charcoal stump

rot.

VI) Secondary root disease: It is caused by a soil fungus Sphaerostilbe repens B. and Br.

which can attack only when the health of the plant is impaired by water logging or impeded aeration

of the soil. The roots turn violet to inky black in colour. On removal of the root bark or sometimes on

the soil adhering to the root surface, characteristic strands of mycelia are noticeable. They are usually

flat, 1-2 mm broad and white at first then turning orange to purplish black with age.

Hosts: A. chinensis, A. falcata, A. odoratissima, A. procera, Derris robusta, Erythrina sp. and

Gliricidia sepium.

60

As in tea, improvement of soil aeration by proper drainage is necessary. Plants like A. falcata,

A. procera and Gliricidia sepium may be killed by waterlogging alone even in absence of the fiungal

element. In one instance waterlogging restricted root development in A. odoratissima to such an

extent that they were easily blown down by storm.

VII) Uncommon diseases: Some diseases of occasional occurrence are here:

a) Ganoderma spp: Two species of Ganoderma have been recorded on shade trees. The

fructification usually appears on the affects trunk or stumps.

i) G. lucidum (Leys ex Fr.) Karst = Fomes lucidus (Leys) Fr. The fructification develops as a

thick bracket the upper surface of which is smooth, yellowish to deep red in colour and concentrically

zonated while the under surface is white in colour.

Hosts: A. chinensis (1919), A. odoratissima (Ann. Rep. 1957).

ii) G. applanatum (Pers ex. Wallr.) Pat = F. applanatus pers ex Wallr.) Gill.

Compared to G. lucidum the bracket in this case is larger in size and thick, hard and dull. The

upper surface is marked with grey and brown concentric zonations while the undersurface is dull

white. The disease was first noticed on A. chinensis in 1934. Ganoderma affected plants may be cut

off to clean healthy wood or uprooted if necessary.

b) Aglaospora sp. was recorded on roots of Albizzia falcataria in the year 1938. Since no

material is available it is not possible to say if it is Tunstallia aculeata Agnihothrudo. Infection in tea

is known through wounds on the above ground portion and thence to roots and is not known to spread

by root contract or through soils.

c) Hattiali disease: Affected plants look sickly and may die out after some time. The roots

bear typical pock marks on the surface.

Hosts: A. chinensis (Ann. Rep. 1960) and Dalbergia sissoo (1948).

61

28. Catalogue of Pests on Shade Trees and Ancillary Crops

The use of shade trees in tea cultivation and green crops in the management of young tea and

fallow land is a well established practice. Pest Management has a very important role in the

silviculture of these plants. The bio-ecology and control of some of the major pests of shade trees and

green crops have been reported and a review of reports on the biology of major shade tree pests was

made by Kakoty. In view of the importance of shade trees and green crops a catalogue of pests has

been presented below. Out of the 147 species recorded so far, beetles rank the highest with 65 species,

moths and butterflies have 40 species, followed by 34 species of bugs, six species of mites and one

species each of termite and nematode. (Gope and Das.1988)

Table 4. Pests of shade trees and ancillary crops

Order Family Species Host Site of

infestation

1 2 3 4 5

Insect Buprestidae Sternocera aurosignata

Thompson

Albizzia odoratissima

Albizzia lebbek

Albizzia procera

Albizzia chinensis

Root

Buprestidae Agrilus beesoni

Oben berger

A. odoratissima

A. procera

A. chinensis

Albizzia lucida

Bark

Buprestidae Agrilus sp. near

A. babaulti Theory

A. lucida Bark

Buprestidae Catoxantha bonvoulloirvi

Deyr.

A. odoratissima Bark

Curculionidae Apoderus dentipes Fst. A. lebbek

Leaf

Curculionidae Apion (=Conapion) sp Tephrosia candida

Priotropis cytisoides

leaf

Curculionidae Cryptorrhynchus sp A. chinensis Bark and soft

wood

Curculionidae Colobodes sp Derris robusta Bark and soft

62


infestation

1 2 3 4 5

wood

Curculionidae Myllocerus

undecimpustulatus Faust

A. lebbek, A.

chinensis

Leaf

Curculionidae Deiradolcus moratus

(Faust)

A. lebbek

A. maranguensis

Indigofera teysmanni

Cerambycidae Xystrocera festiva Thom. A. procera,

A. chinensis,

A. moluccana

A. odoratissima

Heart wood of

trunk

Cerambycidae X. globosa (Olivier) A. maranguensis Heart wood of

trunk

Cerambycidae X. globosa (olivier) A. maranguensis Heart wood of

trunk

Cerambycidae Ropica sp A.odoratissima Heart wood of

trunk

Bruchidae Bruchidius sp T. candida Pod

Histeridae Terelriosoma sp A. odoratissima Soft wood of

trunk

Endomychidae Indalmus kirbyanus Latr. C. anagyroides leaf

Anthribidae Phloeophilus agrestis

Boheman

A. odoratissima Soft wood of

trunk

Tenebrionidae Conocephalum oblongum

(F)

A. odoratissima

Bark

Tenebrionidae Encyalesthus sp A. lebbek

A. maranguensis

Bark

Tenebrionidae Lyphia indicola Geb A. odoratissima Bark

Tenebrionidae Amarygmus cuprarius

(Weber)

A. maranguensis Bark

Lagriidae Lagria ventralis Reitter A. odoratissima Leaf

Lagriidae Aulonogria lemoides I. teysmanni Leaf

63


infestation

1 2 3 4 5

(Fairmaire)

Carabidae Coptodera sp A. moluccana Bark

Carabidae Holcoderus alacer

Andrews

A. moluccana Bark

Monommidae Monomma? glyphysternum

(Marseul)

A. moluccana Stem

Sagriidae Sagara purpurea Licht. C. anagyroides Leaf

Lepidoptera Noctuidae Rhesala meoestalis Walk. A. odoratissima

A. lebbek, A. procera

Leaf

Noctuidae R. impartata A. odoratissima Leaf

Noctuidae Ophiusa sp. A. odoratissima

A. procera

Leaf

Leaf

Noctuidae Hyperaeschea pallida

(Butl.)

C. anagyroides Leaf

Noctuidae Pericyma cruegeri Acacia lenticularis Leaf

Noctuidae P. umbrina Guenee A. lenticularis Leaf

Noctuidae P. detersa Walk Sesbania aegyptica Leaf

Noctuidae Selepa celtis Moore A. maranguensis Leaf

Pieridae Erema hecabae L A. odoratissima, A.

procera, A.

fraxinifolius

Leaf

Pieridae E. blanda silhetana Wallace A. fraxinifolius Leaf

Pieridae Catopsilia crocale Cr. C. fistula, C. siamea Leaf

Lycaenidae Surendra quercetorum

Moore

A. odoratissima Leaf

Lycaenidae Lampides boeticus L C. anagyroides, C.

usarmoensis

Leaf & pod

Lycaenidae Maruca testulalis T. candida Pod

Notodontidae Phalera raya Moore A. lebbek, D. robusta Leaf

Notodontidae P. grotei Moore A. lebbek, D. robusta Leaf

64


infestation

1 2 3 4 5

Notodontidae Boradessa omissa Roth. D. robusta, C. siamea Leaf

Lasiocampidae Cosmotrichia laeta Wlk A. odoratissima, D.

robusta,

Leaf

Geometridae Buzura (Biston)

D. robusta, I.

teysmanni

Leaf

Geometridae suppressaria Guen A. odoratissima, A.

chinensis, P.

cytisoides, Dalbergia

assamica

Leaf

Geometridae Semiothisa sp?

mayandaria Walk

Mimosa invisa Leaf

Arctiidae Diacrisia obliqua Wlk I. teysmanni Leaf

Arctiidae Argina cribraria Cl. C. grahamiana Leaf

Arctiidae A. argus Koll C. grahamiana Leaf

Arctiidae Chionaema peregrina Wlk D. robusta Leaf

Arctiidae Macotasa orientalis

Hampson or close

A. moluccana Leaf

Indarbelidae Indarbela quadrinotata

Walk

A. odoratissima, A.

procera, A. lebbek, A.

chinensis, A.

lenticularis

Bark

Hyperidae Harita nebulosa Moore I. teysmanni Leaf

Gelechiidae Dichomeris ianthes Meyr. I. teysmanni Leaf

Lyonetiidae Leucoptera sp. A. lebbek Leaf

Pyrallidae Etiella zinckenella Tr. C. anagyroides Pod

Pyrallidae ? Oligochroa sp A. moluccana, A.

procera

Pyrallidae Lamprosema paeonalis Wlk D. robusta Leaf

Pyrallidae L. diemenalis Gn. T. candida Leaf

Momphidae Ascalenia sp nr.

liparophanes Meyr.


65


infestation

1 2 3 4 5

Nymphallidae Polyura arja Feld

P. athamus Drury

Charaxes fabius (Fabr.)


Cosmopterigidae Limnaecia sp?

auximona Meyrick

A. lebbek Leaf

Tincidae Dasyses rugosella

Stainton

D. robusta Bark

Tortricidae Cacoccia sp. T. candida Leaf

Hemiptera Psyllidae Psylla oblonga Mathur A. odoratissima, A.

procera, A. lebbek

Leaf

Membracidae Oxyrachis tarandus Fabr. A. odoratissima, A.

procera, A. chinensis,

A. lebbek, A.

fraxinifolius, C.

fistula

Tender stem

Membracidae Centrotypes securis Bicket A. odoratissima Tender stem

Coccidae Coccus elongatus (Sign.) A. odoratissima, A.

lebbek, A. procera

Tender stem

Coccidae Drosicha sp. A. odoratissima, A.

procera, A. chinensis

Tender stem

Coccidae Ceroplastodes chiton

(Green)

A. procera, C.

anagyroides

Tender stem

Coccidae C. cajani Maskell C. anagyroides Tender stem

Diaspididae Pinnaspis strachani (Colley) A. odoratissima Tender stem

Diaspididae Pseudaonidia duplex Ckll A. odoratissima Tender stem

Diaspididae Hemberlesia lataniae (Sign.) A. lebbek, A. procera Tender stem

Diaspididae Lepidosaphes sp. C. anagyroides Tender stem

Diaspididae Pseudaulacaspis pentagona

(Targioni)

P. cytisoides, A.

odoratissima

Tender stem

Pscudococcidae Perissopneumon sp. A. odoratissima, A.

procera

Tender stem

66


infestation

1 2 3 4 5

Pscudococcidae Ferrisiana rirgata (Ckll) A. lebbek, C.

anagyroides

Tender stem

Pscudococcidae Rastrococcus iceryoides

(Green)

A. procera, D.

robusta

Tender stem

Pscudococcidae Crisicoccus sp.

Nipaecoccus vastator

(Maskell)

A. chinensis

T. candida

Tender stem

Stem

Asterolecanidae Asterolecanium sp. T. candida Stem

Plastaspidae Coptosoma sp. T. candida, P.

cytisoides,

Desmodium gyroides,

C. grahamiana, C.

anagyroides

Stem

67

29. Problems of shade tree management in Bangladesh

The following problems of shade tree management generally exist in Bangladesh:

1. A large number of leguminous or non-leguminous trees are recommended for using as

permanent shade trees to provide shade over tea plantation. But in Bangladesh the shade tree

diversity is limited. Only a few species like A. oderaatissima, A. lebbeck, A. procera,

Leucaena leucocephala, A. chinensis, are used extensively. No trial for other species, which

could be used as shade trees, was made. If that could be done biodiversity would be enriched.

2. Few shade trees like A. moluccana are still used extensively; but there are shallow rooted

plants and competes with the tea crop for nutrient and moisture; thus reduces tea production.

3. The climatic and soil condition in Bangladesh is marginal for growing of tea and shade tree.

4. Tea estates in Bangladesh are mostly owned by private companies, that’s why research

recommendations of BTRI scientists regarding different management aspects of tea and shade

trees are not always implemented.

5. Mangers who have been recruited in the tea gardens are not technical persons in most of the

cases and lack in expertise of the proper management of shade trees and tea crop. In many

cases they even know nothing how to manage a tea ecosystem. They just manage the ‘colies’.

Proper silvicultural techniques of shade trees and tea crop are even unknown to them.

6. In many cases matching of species with the site is wrong, as a result shade trees do not thrive

well even fail

7. Sometimes proper spacing of shade trees after thinning is not maintained. Some trees die, but

the gap is not filled again. As a result an even canopy of shade trees is not found over the tea

plantation. In some patches, tea plants get lower amount of sunlight than necessary, while

other patches are flooded with sun which is detrimental for tea growth.

8. In many tea estates proper tea, shade tree, ancillary combination is not maintained. Then

layout recommended by tea scientists are not followed rather they are planted in general way.

9. Proper planting technique is not followed.

10. Number of shade trees per hectare of estates is less or more than the optimum, as a result yield

decreases.

68

11. Lopping of shade trees are not done at right time following right procedure, when the

permanent shade trees are grown height, lapping becomes problematic. Mechanical damage to

the tea plantation is done due to the falling of lops and tops of shade trees.

12. During thinning of shade trees damages to the tea plantation is done.

13. As a result of uprooting of shade trees, the topsoil is exposed to the direct hit of the raindrops,

thus enhances soil erosion.

14. Sometimes shade trees enhance the chance of post attack to the tea plants. Lops and tops of

shade trees left in the upper soil during lopping, thinning and mulching harbour various insects

and fungus.

15. The labourers engaged to carry out silvicultural operations of shade trees are not trained to the

right procedure of action.

16. Once a tree has been felled, it is advisable not to allow a stump to remain above soil level. It

should be cut to a point below soil level and covered with earth. But in many cases this is not

done. As a result posts get good harbouring place in the rotten stump.

17. Planting materials are sometimes prone to wind damage for not providing proper shade trees

and shelterbelt to protect them form destruction of strong wind prior they are planted.

18. Litter and Mulches, which are provided from the cutting of shade trees, are often washed to

the valley from the slopes due to rum-off. As a result upper hill slopes get less nutrient then

lower slopes or vallies.

69

30. RECOMMENDATION

For better management of tea plans and shade trees and to increase quality and yield of tea and

shade tree, the following recommendation are suggested-

1. Deep-rooted leguminous trees should be selected as shade trees for using in the tea estates.

Shallow rooted trees like A. moluccana should be discarded as they compete with the rain crop

tea for nutrients.

2. Shade trees should be leguminous providing higher litter fail and fixes N2 to the soil.

3. A wide variety of trees should be tried instead of a few commonly used ones to increase

biodiversity. This would harbour various birds and other wild lives and would contribute to the

maintenance of environmental balance. Acacia auriculiformis, Acacia mangium, Dalbergia

sissoo, etc. fast growing species should be planted as shade trees along with commonly used

species which would provide demand of fuel wood to the local community tea laborers.

Figure 7: Acacia auriculiformis used as shade tree at Rasidpur Tea Estate

4. Research recommendations of BTRI scientists regarding various aspects of shade tree and tea

management should be properly implemented. Private companies must be liberal towards the

innovations recommended by the tea scientists.

5. For proper management of tea estates, professional Forester should be appointed. Trained

manpower for tea gardens management is generated by Institute of Forestry and

70

Environmental Sciences, Chittagong University on regular basis. They should be recruited in

the tea estates for better management.

6. The labourers should be given training of the proper method of silvicultural operation of

shade trees like lopping, uprooting, planting, pruning, thinning, fertilizing etc to increase

productivity.

7. Right species should be selected for right soil and climatic characteristics. Matching of species

with site is important for a successful tea plantation.

8. Proper spacing and planting technique should be maintained throughout the plantation.

9. An optimum number of shade trees per hectare should be retained in the tea estates which

would allow required amount of sunshine (50-70%) break through the canopy for optimum

growth of tea plants.

10. Lopping and thinning of shade trees should be done at the right time following right procedure

when the shade is heavy. Care should be taken so that tea crop is not damaged much.

11. Once a shade has been felled he stump should be covered with soil otherwise when it rotten

allows harbouring of insects and fungus, which may infect tea crop.

12. Present tea soil is extremely degraded and exhausted, strongly acidic with less quantity of

organic matter and other essential plant food elements. Thus future policy must be designed to

accelerated to improved and management of the soil as to obtain maximum productivity and

maintain fertility of the soil by planting right type of shade trees, available green corps and

cover crops.

13. Cultural operation such as weeding, vacancy filing, maturing, pruning, tipping and plucking

should be done properly, which influences the growth and quality of tea.

14. Shade tree is a very much profitable cash crops; adequate shade trees of suitable species

should be planted in the estate. Shade tree is not provide only shade it also product fuel wood

and timber to meet the present need.

71

31.CONCLUSION

Bangladesh produces tea in marginal climatic and soil condition. The yield and quality of tea

in our country is lower than many other tea-producing countries of South Asia like India and Sri

Lanka. To increase yield and quality of produced tea, proper selection and judicious manipulation of

shade trees are very much important. An improper combination of shade tree, tea plant and ancillary

crop even may lead to failure of the plantation. The importance of shade trees in tea plantation is

crucial. Right type of shade trees should be chosen for right soil and climatic condition. A good

management of shade trees should be ensured. Professionals, who have expertise and good knowledge

in the related field like forestry graduates, should be recruited in the tea estates for their better

management to increase yield of tea. BTRI recommendations regarding shade tree management

should be implemented practically in the filed.

72

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