AMOL VIJAY SHITOLESUBJECT- PLANT PATHOLOGY

EFFECT OF NUTRIENTS ON CITRUS DISEASES

1. Soil and environment2. Mineral nutrition essential for plant and organism3. Plant diseases interaction 4. Nutrient stress5. Pathogen changes plant physiology6. Pathogen infect plant root7. Secondary infection8. It is clear that the severity of most of diseases can be reduced and

the chemical , biological or genetically control of many plant pathogens enhanced by proper nutrition. (Dr. D. M. Huber states)

Introductions

The study of plant disease often begins with a discussion of the “plant disease triangle”.

1. The three legs of the triangle – host, pathogen, and environment .

2. If any of the these factors is altered, changes in the progression of a disease epidemic can occur.

3. Nutrients impact on all aspects of the diseases cycle.

PLANT DISEASE

Nutrient Chemical symbol Function in plant

Nitrogen N Proteins, amino acids

Potassium K Catalyst, ion transport

Calcium Ca Cell wall component

Magnesium Mg Part of chlorophyll

Phosphorus P Nucleic acids, ATP

Sulfur S Amino acids

Chlorine Cl Photosynthesis reactions

Iron Fe Chlorophyll synthesis

Boron B Cell wall component

Manganese Mn Activates enzymes

Copper Cu Component of enzymes

Zinc Zn Activates enzymes

Molybdenum Mo Involved in N fixation

Essential mineral nutrients required by all plants for normal growth and development

Relative nutrient balance for citrus

There are two primary resistant mechanism that mineral nutrition can affect .1.Formation of mechanical barrier 2.Synthesis of defense compound :-

(Phytoalexins, antioxidant and flavonoids)

Defense Mechanism In Plant Against Pathogen

Most Important Nutrient's For Disease Resistance

*K, Ca, Cu, B, Mn, S, Si

Not essential, but beneficial

NITROGEN (N)ROLE OF NITROGEN IN PLANT Formation of various structure protein and enzyme needed both in growth and diseases resistantFUNTION OF NITROGEN:-1. High nitrogen rate lead to more disease but2. Proper nutrient suppress diseases.3. N contain increases amount of antifungal

compound decrease.

* Effect of different nutrient 0n citrus diseases

* Correlation of factor influencing the form of N in soil and severity of diseases

take all FACTOR NITRIFICATION DISEASES

NITRATE NITROGEN …. DECREASES

AMMONICAL NITROGEN

…. INCREASE

LIMING INCREASES INCREASES

ACID SOIL DECREAS DECREASES

CHLORIDE DECREASE DECREASES Menge et, al. 1979

EFFECT OF DIFFERENT FORM OF NITROGEN ON CITRUS DISEASE

K+ most important insect and diseases reduction.Role of potassium:-

1. Mobilizing of plant defense system.2. Increases cuticle thickness.3. Tolerance to adverse condition.4. Stress: Heat, cold, drought.

Potassium K: 4 issues Tied up in clay soils. Slowly available from native soils. Leaches out in light soils. High nitrogen overcome K effect. Dr. Steve Petrie et.1992

* POTASSIUM (K)

Role of potassium:-1. K is involved in cellular function :- synthesis of

protein.2. Mobile regulator of enzyme activity. k reduce susceptibility to plant to pathogen but beyond sufficient leval of k there is no additional benefit from supplying additional k (Huber and Graham 1999).

*POTASSIUM

SOIL K DISEASES REDUCED DUE TO K

YIELD RESPOSE DUE TO K

LOW 48% 88%

UNKNOWN 14% 60%

Spectrum Analytical, inc (Washington)

Effect of potassium in citrus Phytopthora root rot

1.Citrus plant susceptible to diseases if they are suffering from k deficiency.2. Phytopthora root rot (P.parasitica )of citrus was increases by high leval of k fertilizer.3. Because high k uptake probably caused a shortage of Ca. 4. Shortage apparently resulted in improper formation or function of the plant cell wall.

*Effect of K, N and Ca on Severity of Phytopthora Diseases

Pathogen Host\ disease Factor Effect

P. infestance Potato Late Blight K DecreaseK NoneHigh KHigh N Increase

P. capsici Pepper Blight K DecreaseP. drechsleri Pigeon Pea Blight

High KLow N Decrease

P. parasitica Citrus GummosisHigh KLow Ca Increase

Phytopthora , Its Biology, Taxonomy, Ecology and Pathology , 1983 , APS Press, St. Paul , MN Page 191

*PHOSPHORUS (P) 1.Taken up by plants as HPO4

2- or H2PO4-

•Important for energy transfer in plants•Cell division and proper growth•Creates a stay-green effect in plants

2. Relationships with disease is inconsistent

3.Reduce plant stress, improves resistance and decreases disease risk

*Why P Affects Disease1.Increase in plant maturity that

attacks young plant tissue.2.Increased plant vigor with adequate

P.3.Highly specialized pathogens may

attack vigorous plants, while less specialized pathogens attack weak plants.

4.Increases plant defense mechanisms.

1.Seedling infected with mycorrhizal fungus and P. parasitica

2.Influence of Mycorrhizal fungus on diseases.3.P. parasitica were influenced by phosphorus

nutrition.4.Ability of Mycorrhizal roots to absorb more

phosphorus and possibly other mineral than non mycorrhizal roots.

(Devis et, al.1997)

* Determine the role of phosphorus in the interaction between V A Mycorrhiza and P. parasitica on citrus

* Percentage of root of sweet orange seedling treated with various

combination Glomus fasiculatus, Phytopthora parasitica, and three

levels of soil phosphorus

Soil Phosphorus (µ g P/g soil)

TRETMENT 6 56 600

No infected 100 100 100

Phytopthora parasitica 33 74 86

Glomus fasiculatus 100 100 100

P. parasitica+ G. fasiculatus 50 72 79

Healthy Root %

Devis et al., 1997

* Effect of phosphorus on release of zoospore by sporangia of

Phytopthora parasitica

Equivalent concentration

Phosphorus H3PO4 Empty sporangia

(mg/L) (Mm) (% of control)

0 0 100

10 0.3 89

50 1.6 43

100 3.3 13

300 9.9 3

600 19.8 0R.M. Devis and J. A. Menge et.1979

1.Growth of colonies of P. parasitica was not affected by phosphorus.

2.Germination of sporangia however , were more sensitive and was inhibit by phosphorus .

3.A Significant reduction in the release of zoospore was detected in solution with 50 mg P/L water and 600mg P/L water. No sporangia release zoospore.

*Effect of phosphorus on P. parasitica

Role of calcium:-1. Structural component of cell wall and other plant

membrane.Mechnism of Ca against plant pathogen

• Cell wall regulate the passage of and other compound between cell and other parts.

• When Ca is low it permits increases transport of sugar from within the cell to the intracellular spaces in the plant tissue.

• Higher sugar leval in this area tends to increases chances of infection and growth of diseases pathogen.

*CALCIUM (Ca)

CALCIUM(Ca++)

1) Fortifies the middle lamella Middle lamella= Calcium pectate2)Slow degradation by pathogen3)Stops motile spores-zoospores phytophthora and pythium4)Salanity stress can increase Phytopthora root rot through increase zoospore attachment on roots5) Ca and B deficiency also cause mineral imbalance that lower resistant to diseases by creating more favourable environment for plant growth.

* Zn, Mn and B

Role of n Zinc Role of Mn Role of B

1. It is essential to the integrity and stability of the plant membrane and it is thought to help prevent “leakage” of the essential element S or compound from plant cells.

1. Involved in the production of lignin.

2. Mn inhibit the enzyme pectin methyl-esterase.

3. Methyl –esterase is a fungal pathogen exoenzyme for degrading pathogen.

1. Increases the uptake of cation .

2. K, Ca, Cu are cation that are vital for plant resistant to diseases.

3. Involved in metabolism of phenolic.

4. Phenolics include phytoalexins and other molecule that are toxic to plant pathogen.

1) Change in plant nutrition associated with Huanglongbing HLB (“nutrient defiance like”)

2) HLB accumulate large amount of starch because bacterium caused phloem plugging .

3) High leaf starch :-disturbed chloroplast and loss of chlorophyll

4) HLB increases K while Mg, Ca and B decreases5) K increases in clay loam 6) K decreases in sandy soil7) Micronutrient Zn and Mn deficiency symptoms found.

(Imothy et. al.2009)

*Overall NPK and Zn status in plant tested

for HLBElement Status No of plant %

N deficient 83 71.55

Satisfactory 33 28.24

P Deficient 99 85.34

Satisfactory 17 14.65

K Deficient 70 60.34

Satisfactory 46 39.65

Zn Deficient Nil Nil

Satisfactory 116 100 (Muhammad et. Al.,2011)

1.All essential nutrient are critical for the proper metabolic functioning of citrus tree. 2.A balance between macronutrient and micronutrient is needed to optimize the yield of high quality fruit and maintain tree healthy and tolerant to pest diseases and other stress.

*CONCLSUION

3.Maintaining appropriate levels of nutrients will maintain productivity and inhibit disease.4.Many interactions occur that have resulted in the nutrient recommendations we currently use.