10/6/2014

1

OLERICULTURE

Hort 320Lecture 9

N.R. (Rick) Knowles, Professor

Washington State University

Rm 43 Johnson Hallrknowles@wsu.edu

N.R. (Rick) Knowles, Professor

Washington State University

Rm 43 Johnson Hallrknowles@wsu.edu

POTATOES

Lecture Outline

� Classification

� Origins & domestication� nutritional attributes

� scope of production (production trends) & importance

� Botany, morphology, anatomy

� Production – planting to harvest� propagation – importance of apical dominance

� phases of growth & development� sprouting� emergence & plant establishment� flowering & tuberization� tuber bulking� foliar senescence� tuber maturation

� controlling tuber set & size distribution� stem number/tuber set relationships – seed age� seed spacing� hormone treatments

� Harvest, postharvest handling & storage considerations� maturation & skin set

� minimizing bruise

� wound healing, cooling & holding periods� sugar buildup� managing dormancy� reconditioning & removal

Additional Reading & InvitationAdditional Reading & Invitation

�Potato Health Management ch 10 pp 79-99.

�Participation in the NW Variety Development Program – French fry culinary evaluation trials#

�Week of October 13, Johnson Hall Pilot Plant –prizes & coupons for participation (~1-4 pm).

�Evaluation of fries from clonal entries grown in regional & tri-state trials of WA, ID and OR in 2014.

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� Solanaceae ‘nightshade’ family (other members

include tomato, pepper, eggplant)

� 5th most important crop worldwide after

sugarcane, corn (maize), rice & wheat (total

tonnage basis).

� Herbaceous perennials with white, blue, pink,

purple, or red flowers with yellow stamens

� Range of ploidy in wild & cultivated species: 2n,

3n, 4n and 5n – cultivated potato is tetraploid

(n= haploid # chromosomes =12 in potato).

� High morphological diversity with a great variety

of shapes and colors of tubers.

� Green portions of plant contain toxic

glycoalkaloids (solanine, chaconine, etc.) – role

in plant defense

Potato (Solanum tuberosum L.)

Classification

1570

1621

‘Ozette’

1700s

Solanum tuberosum Origin and

Domestication

Native to S. Am. – Andean

mountain regions of Peru &

Bolivia

The Irish Potato Famine 1845-52

�Late Blight oomycete (Phytophthora infestans) -

destroyed potato crops all over UK & Western Europe.

�~1 million died, a million more emigrated to U.S.,

Ireland’s population fell 20-25%.

�Reasons - lack of genetic diversity (cv ‘Irish Lumper’) +

large dependency on potatoes as sole crop & food

source (~33% of the population).

�Stimulated potato research – especially variety

development & disease resistance.

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‘Defender’

• Released in 2004

• Primarily Processing

• High Yield & Specific Gravity

• High Vitamin C

• Bulks Rapidly

• Good for Organic ProductionAm J Pot Res (2006) 83:9-19

Weaknesses:Blackspot, scab, greening,short dormancy

� Resistant to Late Blight� Foliage� Tuber - very

� Also Resistant to:� Tuber early blight, PVX, net necrosis and PC Nematode

� Moderate Resistance:� Early dying, pink rot, corky ringspot, PVYO, and soft rot

Northwest Potato Variety

Development Program

Late Blight Screening Trial Bonners Ferry, ID (2004)

� No fungicides

� Late blight inoculated

Late Blight Susceptible:

Dead Vines

DefenderCourtesy of Dr. Jeff Miller

� Food Energy per Acre:

� 75% more than wheat; 58% more than rice

� Vitamin C:

� 45% of required daily value (med-size potato)

� Ranger, Defender, GemStar: 30% higher than Russet Burbank

� Protein

� ~54% more protein/A than wheat; 78% more than rice

� Good balance of amino acids

� Biological value of potato protein = 90-100 (chicken egg std = 100)

� Classic and Clearwater Russet: 32% & 38% higher-Burbank

� Phytonutrients/Anti-Oxidant Compounds

� Polyphenols, flavonoids, carotenoids

� Yukon Gem, Purple Pelisse

Potato Nutritional Qualities

Nat’l Potato Council

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World Potato Production

Rank Location

World

Production

1 China 23.5%

2 India 12.3%

3 Russian Fed. 8.1%

4 Ukraine 6.4%

5 USA 5.3 2012

364,868,768 Tons

U.S. Total = 1,131,900 A

2012

49%

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USA Potato Production 2012 (total cwt)(418,779,000 cwt = 41,877,900,000 lbs)

62%21%

13%

NASS 2012

PNWNorth Central Eastern

Southwest

9.4%

20.8 T/A

416 cwt/A

U.S. Potato Production

Seed & fresh red/specialty prod’n

�Potatoes rank 3rd behind apples & wheat in value

�87% of crop is processed

�~65% of processed fries are exported to Japan

�23,500 jobs & ~$4.6 billion to WA economy

Seed prod’n

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WA Potato Industry Spotlight

2014

Whole Plant

Morphology

Perennial,

herbaceous,

dicotyledonous plant

Indeterminate growth

habit, although many

cultivars have been

bred to have more

compact & bushy

growth habits.

Leaf Morphology

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Stem Morphology

style

stigma

Anther cone

Stigma is

exerted beyond

the anther cone

Floral Morphology

Complete –

sepals (1),

petals (4),

stamens (2),

pistil (3.1-3.3)

Ripe fruit showing seeds

Developing fruit

pollination ripening

seed

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Tuber Morphology &

Anatomy

Apical or

bud end

Basal or

stem end

Note the

variation in

different stages

of tuberization

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Tuberization

� Daylength – photoperiodic SD response

mediated by phytochrome (protein/pigment photoreceptor

complex in leaves sensitive to light in red & far red spectral regions)

� Day/night temperature – warm days cool nights

induce tuberization; constant high temperature (day/night) inhibits tuberization.

� Stress – nutrient, water, disease, etc.

Tuberization & Flowering may be mediated by the same

Phloem-transported Signal similar to Flowering

Interaction of Photoperiod & Temperature

(day/night) to affect Tuberization

∆T day-night

0

36 F

12.5 F

No yield

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Effects of day-length &

temperature on foliar

growth

8 h

70-80oF

16 h 8 h

60-70oF

16 h

Effects of day-length & temperature on foliar growth

Propagation

� Vegetative – cuttings (‘seed pieces’)

from certified seed-tubers

� Seed potatoes are grown in areas

geographically isolated from

commercial production

� Certified as to cultivar and virus-free

status.

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sectorial

chimera =

somatic

mutation

Russet Burbank Cultivar:� ~42% of PNW production (2013)� Rapidly being replaced by more efficient varieties (was 83% in 1992)

� The original Burbank was a smooth white/buff-skin potato

� Russeting was selected later (in CO) from a somatic mutation of the periderm of the original Burbank

� Mutation is a sectorial chimera (somatic mutation)

� Russet Burbank (also called Netted Gem)

Seed potatoes

entering cutting

facility

Seed is first sized

according to weight, then

sent through cutters to get

maximum # seedpieces

from each tuberG

Targeting 1.5-2.5-oz

seedpieces (ideal = 2.25

oz)

Seed cutters with

orientation rollers

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Seed emerging

from cutter

Planting

Air cup planter

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Typical planting & spacing (Col Basin)� 8 inches deep

� 10 inches between seed pieces within a row

(can vary from ~8-12)

� Rows 34 inches apart

� 1.5-2.5-oz seed pieces

Nutrient & H2O use

� require high levels of fertilizer (N, P, K e.g.

350-400 lb N/A) & H2O

� ~1/3 N & P incorporated at planting, rest is

delivered through pivot during growing

season through end of July.

� Maintain soil moisture > 65% field capacity.

Seed piece size & plant establishment

0.75 2.0 2.5 3.01.51.251.0

Seed Piece Weight (ounces)

Date

Seasonal N Rates (lb/A)*

278 365 453

In-season N (lb/A)

6/4 6 15 30

6/11 30 30 40

6/17 24 30 35

6/20 24 20 30

6/25 12 20 30

7/2 - 20 25

7/9 - 18 25

7/16 - 10 25

7/23 - 10 16

7/30 - 10 15

*Includes 182 lb/A (203 kg/ha) N pre-plant

(incorporated + residual).

Typical N fertigation

schedule for a late season

long russet cultivar in the

Columbia Basin

14 DAE

21 DAE

28 DAE

DAE = days after emergence

Expect 100% emergence ~35

days after planting (mid April

planting).

Ideal regime

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VRI Center Pivot with mixing tanks (Othello)

June 15 June 30 July 15 July 30

Pe

tio

le N

itra

te (

%N

O3

-N)

1.5

1.9

2.3

2.7

3.1 2.7 to 3.0

2.1 to 2.4

1.8 to 2.1

1.5 to 1.8

Alpine Russet

June 15 June 30 July 15 July 30

1.5

1.9

2.3

2.7

3.1

2.9 to 3.2

2.6 to 2.9

2.4 to 2.7

2.2 to 2.5

Sage Russet

Recommended Petiole NO3-N Ranges for Maximize

Economic Return of Alpine & Sage Russet

Stages of crop growth & development

� sprouting

� plant emergence & establishment

� flowering & tuberization

� tuber bulking

� foliar senescence & tuber maturation

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Tuberization

& flo

wering

Tuber Bulking

Foliar senescence

& tuber maturation

Em

erg

ence &

pla

nt

esta

blishm

ent

Days After Planting

40 60 80 100 120 140 160 180

Fo

liar

Gro

wth

(T

/A)

0

5

10

15

20

25

30

35

40

45

50

55

Tu

ber

Yie

ld (

T/A

)

0

5

10

15

20

25

30

35

40

45

50

55Alpine Russet

foliar

growth

tuber yield

Cumulative Degree Days (45o

F base)

38.6 T/A

453 lb/A N

636 1084 1582 2086 2556 2951 3228208

Total Biomass

Stages of crop growth& development� sprouting� emergence & plant

establishment� flowering & tuberization� tuber bulking� foliar senescence & tuber

maturation

Knowles, et al.

2011-13 Columbia Basin, Othello, WA

Tuber set & size

distribution greatly

affects crop value

Late Frozen-Process Contract

�Base price (e.g. $133/ton)

�Premiums & Penalties� % market yield above 6 oz

� Specific gravity – sweet spot =

1.083-1.088

� Oversize clause

� Bruise clause

Estimating tuber size distribution

at Simplot French fry plant

Estimating & eliminating bruise at

Simplot French fry plant

Blackspot bruise due to polyphenol oxidase (PPO) –

InnateTM from Simplot Inc. silenced PPO

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Simplot French fry plant

Tuber Specific gravity

measurement

Sp gravity = wt in air(wt in air – wt in H2O)

% Dry Matter = 24.182 + 211.04 (SG)

DM is fundamental to the yield of solids (ie the non-water component of potato – mostly starch) in processing crops, which affects oil absorption and texture in fried, baked or boiled potatoes.

SG is directly proportional to % dry matter & % starch content.

Dry matter content is also used generally as an indicator of bruising risk, with high DM associated with more damage.

Controlling tuber size distribution

� Physiological age of seed at planting

� In-row seed spacing

� Plant growth regulators

� Timing the harvest

� Cultivar

Stem Number, Tuber Set & Size Relationships

High apical

dominance

Low apical

dominance

Seed physiological age

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Physiological & Developmental Indicators

of Advanced Seed-tuber Age

� Shortened dormancy

� Early sprouting in storage

� More rapid emergence & plant establishment

� Reduced apical dominance – increased stems

� Increased tuber set per plant

� Shift in tuber size distribution

� Effects on yield depend on extent of age, cultivar, & length of growing season

In-row seed spacing affects tuber set & size

*tuber number per plantcv. Ranger Russet

6-in 10-in 14-in

2.8-stem seed lot

In-row spacing (inches)

7* 9 10

(young seed)

Older tubers have a greater ability to

breakdown auxin (IAA oxidase) and

sprouts from older tubers have reduced

ability to translocate auxin

Auxin - IAA

Active

apical bud

Inhibited

lateral bud

Auxin Has a Major Role in

Regulating Apical Dominance

Kumar & Knowles (1993) Can J Bot 71:541-550Kumar & Knowles (1993) Can J Bot 71:541-550

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NAA Concentration (mg L-1

)

0 33 66 99

Ste

ms p

er

Seedpie

ce

1.6

2.0

2.4

2.8

3.2

3.6

4.0

4.4

4.8

5.2 Ranger Russet

3-yr 07-09 Avg.

(600 deg-day)

(80 deg-day)

R2= 0.98**

R2= 0.98**

2.8-stem seedlot

4.8-stem seedlot

Restoring Apical Dominance with Auxin(auxin decreases stem numbers)

36 T/A

35 T/A

34 T/A

34 T/A

Age x NAA**

Tot YldsNAA, naphthalene acetic acid

Auxin Product on the Market

Treating Seed with Gibberellins Breaks Dormancy Hastens

Emergence & Increases Stem Numbers

GA (ppm)

0.0 0.5 1.0 2.0 4.0

Ste

ms p

er

Seedpie

ce

3.0

3.5

4.0

4.5

5.0

5.5

6.0 Red LaSoda

R2= 0.96**

GA (ppm)

0.0 0.5 1.0 2.0 4.0

Em

erg

en

ce

(%

)

0

20

40

60

80

100Red LaSoda

R2= 0.94*

31 DAP

Red LaSoda, Yukon Gold, Chieftain, Cal White, Satina

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Re

d L

a S

od

a

GA

ppm

Yield

T/A

% Change in value from control Total %

ChangeA’s(92-360 g)

B’s(67-91 g)

C’s(10-66 g)

0 18.5 0.0 0.0 0.0 0

0.5 20.3 8.1 23.3 3.2 9.1

1 20.4 4.8 30.0 9.7 10.2

2 19.4 -16.1 36.7 51.6 11.4

4 18.8 -24.2 40.0 67.7 12.0

Gibberellins as a Pre-plant Seed Treatment can Shift

Tuber Size Distribution & Crop Value(Red La Soda)

Vine kill 90 DAP

Harvest 103 DAPBlauer & Knowles (2013) Am J Potato Res 90:470-496

GA Products on the Market

U.S.A. Canada

Harvest, Postharvest Handling & Storage

Considerations

Harvest, Postharvest Handling & Storage

Considerations

Challenge – transfer a healthy crop from underneath

the soil to bulk storage with minimal damage (i.e.

minimize the ‘trauma’)

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� Bruising & skinning

� Improper curing (wound-healing)

�Weight loss

� Starch breakdown

� Sugar buildup

� Decay

� Sprouting

� Greening – chlorophyll development

Causes of Postharvest Losses

Maturation & Skin-set

� Native periderm (skin) is fragile while actively growing – high susceptibility to skinning.

� Water loss from non-damaged tubers (prior to skin set) is up to 28 times greater than from mature tubers in which periderm has “set”.

� Skin set occurs during maturation under dead vines, typically within 10-21 days of vine death.

� Skin-set involves death of the phellogen (cork cambium), which cements the outer phellem layer firmly to the underlying cortical cells.

� Can test for skin set by “slipping the skin” on freshly dug potatoes.

� If tubers are immature (e.g. from green vines), skin set will continue in storage.

Result of Chemical desiccation of Russet

Burbank vines with Reglone (Diquat = a.i.)

N.R. Knowles, WSU

Choices

Chemical desiccation

Mechanical flail mowing & rolling

Green vine harvest

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Lulai, E.C. 2007 In Potato Biology & Biotechnology, Elsevier

Skinning/excoriation injury to immature

native periderm

Sou

rce

s o

f M

echa

nic

al In

jury

(%

)

0

20

40

60

80

100

Harvester(70%)

Bulk Truck(14%)

Bin Piler(14%)

Rollback on PileFace (2%)

Mechanical Injury

Knowles et al.

2008. In Potato

Health

Management 2nd

ed. APS Press

Location in Harvester

Pe

rce

nt

Bru

ise

Da

ma

ge

0

10

20

30

40

50

Dig

ge

r B

lad

e

Pri

ma

ry C

ha

in

Dro

p o

nto

Se

co

nd

ary

Ch

ain

Dro

p o

nto

Re

ar

Cro

sso

ve

ra

nd

on

Re

ar

Cro

sso

ve

r

Dro

p o

nto

Sid

e e

leva

tor

On

Sid

e E

leva

tor

Dro

p O

nto

Bu

lkB

oo

m C

ha

in

On

Bu

lk B

oo

m C

ha

in

On

Se

co

nd

ary

Ch

ain

Areas of Harvester &

their Relative

Contributions to

Bruise Damage

Areas of Harvester &

their Relative

Contributions to

Bruise Damage

Bruise Damage to more

than 3-4% of the crop is

excessive

Load the harvester to

capacity by adjusting chain

speeds relative to forward

speed of tractor to

minimize damage

Knowles et al. 2008. In Potato Health Management 2nd ed. APS Press

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Harvesting tubers at physiological maturity – note

condition of vines

Knowles et al. 2008. In Potato Health Management 2nd ed. APS Press

Note drop height into truck (≤6 inches is ideal)

Knowles et al. 2008. In Potato Health Management 2nd ed. APS Press

Tarp

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Uniform tuber

distribution

A stepped bin-piling

procedure minimizes

roll back and

damage on the pile

face.

Knowles et al. 2008. In Potato Health

Management 2nd ed. APS Press

In-floor ventilation ducts

Knowles et al. 2008. In Potato Health Management 2nd ed. APS Press

16-18 ft pile

∆T ≤ 2oF

Airflow

warmer

colder

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Knowles et al. 2008. In Potato Health Management 2nd ed. APS Press

Top surface of

18 ft pile

0.5 – 2oF warmer

than floor

Storage bay 1 Storage bay 2

Central Plenum

20 cfm/tonVentilation duct

running under

floor

Door

Curing (wound healing) after Harvest

� Potatoes need to be stored for approximately three

to five weeks (in practice) at 50 to 60oF and ≥95 %

relative humidity.

� Supply high rates of ventilation (20 cfm/ton).

� During this time, potatoes become more resistant to

storage diseases and shrinkage.

� Wound healing and suberization (formation of a

protective layer between the tuber surface and the

interior tissue) take place during this period.

� Required for all potato lots, regardless of storage

time and intended use.

Wound

Suberized cells

New phellem (cork) cells

New phellogen (cork cambium)

Storage parenchyma

Wound

Healing

Suberization of wound surface

phellodermphelloderm

Increased H2O loss &

Wound respiration = heat & loss of dry matter

Kumar & Knowles, WSU

10/6/2014

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(Bernards, 2002. Can J Bot 227-240)

Poly(phenolic)

domain Poly(aliphatic)

domain

Suberin lamellae Primary cell wall

Temperature Profile of Commercial Seed

Storage from Harvest to Planting

Days from Vine Kill

32 46 60 74 88 102 116 130 144 158 172 186 200

Sto

rage

Te

mp

era

ture

(oC

)

2

4

6

8

10

12

14

Sto

rag

e T

em

pe

ratu

re (

oF

)

36

40

44

48

52

56

Stored from10-17-07 to 4-1-08

harv

est

(10

-17

-07

)

pla

nte

d (

4-1

1-0

8)

20

9 D

AH

Russet Burbank

Wound healing

Pull down

Holding

0.4oF/day

French fry potatoes

Fresh market potatoes

Seed potatoes

Knowles, WSU

Period of Storage

Curing Cooling Holding Marketing

Temperature Maintain tuber pulp temperature at:

• 55-60oF if tubers are healthy

• 50oF if some

tuber decay is present

Rapidly cool seed and fresh-market tubers to the appropriate holding temperature

Slowly cool processing tubers, lowering pulp temperature by 2-3oF per week

Maintain tuber pulp temperature at:

• 37-39oF for seed

• 40-42oF for

fresh market

• 44-48oF for

French fry processing

• 50-55oF for chip processing

Warm slowly to 50-55

oF over

several weeks

Rel. Humidity 95-99% 95-99% 90-95% 90-95%

Ventilation Supply at high rates to remove

field heat, stabilize pile temperature,

reduce CO2 buildup and

provide O2 for wound healing

Supply at high rates to control

cooling and maintain

differential of 0.5-2oF from bottom to

top of pile during cooling

Supply at reduced rates, adjusted as

necessary to supply O2, remove CO2 and maintain differential of 0.5-

2oF across pile

Supply at reduced rates to allow heat

of respiration to raise pulp

temperature to 50-55

oF and thus

minimize bruising during removal from storage

Environmental Management for Maintaining Tuber Quality in Storage

Knowles et al. 2008. In Potato Health Management 2nd ed. APS Press

Main concern is

prevention of low

temperature

sweetening (LTS)

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Reducing Sugar (glc + fru) Accumulation

� Dependent upon:

• Variety

• Storage temperature

• Physiological maturity

• Stress problems and defects

• Tuber age

� Sweetening is not an issue at 50-55oF for most varieties

� LTS is partly reversible depending on tuber age. When tubers reach an age where sweetening cannot be reversed they are said to have undergone “senescent sweetening”

� InnateTM potatoes from Simplot Inc. – silenced gene for invertase = no sweetening at low temperature

LTS = low temperature sweetening Knowles, WSU

Dark FriesStarch Sucrose Glc + Fru heat

Amino acids

Maillard Reaction

Invertase

Premier Russet

Defender

12 18 42 6326

Reconditioning(60oF)

Low Temperature (39oF) Storage Period(Days after Harvest)

apical

basal

*USDA color scale 0 (light) to 4 (dark)

Cold-induced Sweetening

2-months

14-months

26-months

0 7 14 23Storage Time

(39oF)

Reconditioning (days at 73oF)

Senescent Sweetening Cannot be Reconditioned

Knowles, WSU

10/6/2014

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Approximate Length of

Dormancy (days)

Cultivar 42oF 45oF 48oF

Russet Burbank 150 135 120

Ranger Russet 75 60 50

Summit Russet 150 125 100

Umatilla Russet 140 120 80

Effects of Storage Temperature & Cultivar

on Length of Dormancy

Kleinkopf & Olsen (2003) In Potato Production Systems, Univ. of Idaho

Inhibitor Structure Chemical or trade name

Mode of action

& application

CIPC Chloroisopropyl carbamate

(chlorpropham)

Cell division inhibitor;

postharvest – before

dormancy break

MH Maleic hydrazide (MH-60) Cell division inhibitor;

preharvest – before

vine senescence

DMN 1,4-Dimethylnaphthalene Auxin; cell cycle

inhibitor; postharvest -

before & after

dormancy break

DIPN 2,6-Dimethylnaphthalene

(Amplify)

Auxin; postharvest

(augments CIPC)

Eugenol Clove oil (Biox C) Pinching agent;

postharvest – after

dormancy break

3D2 3-decen-2-one (SmartBlock) Pinching agent;

postharvest – after

dormancy break

Potato Sprout Inhibitors

Knowles, WSU

Cl N

O

O

NN

O

O

Rick Knowles

Office: 43 Johnson Hall

Lab: 133 Vogel Plant Biosciences

rknowles@wsu.edu

509-335-3451