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Chapter 24 Potatoes Link to New York Potato Crop Profile See New York Potato IPM Elements Link to Resource Guide for Organic Insect and Disease Management
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See Cornell Report: NEW
YORK CERTIFIED SEED POTATOES VARIETY DESCRIPTIONS
New York Certified Seed Potatoes - 2007 Crop Directory
Only certified seed (2007 Crop Directory) should be used. Diseased seed not only affects the plants that grow from it but puts the rest of the field and the whole farming operation at risk because many diseases can be spread by cutters, planters, and other equipment. In addition, diseased plants from affected seed tubers serve as the primary inoculum source from which other plants in the field can be infected as the inoculum is spread by wind, rain, and insect activity. This is the same risk posed by leaving cull piles exposed in the vicinity of production fields. A grower often cannot tell by looking at tubers whether they will be good for seed. Fortunately, the New York State Foundation Seed Certification Program can survey for these problems. Seed growers can obtain meristem-produced, disease-free plantlets or high quality seed from the Uihlein Foundation Seed Potato Farm at Lake Placid, which is administered by Cornell University. Seed producers are required to use a "flush-out" system, obtaining new seed from the state seed farm each year and producing a limited number of generations. Seed more than four or five generations old often poses a higher production risk for commercial use because repeated field exposure increases the probability of disease introduction and spread within a seed lot which may reduce yields significantly and pose a serious risk of other problems.
When handling seed, growers should maintain lot identity and prevent contamination. Trucks, storage, and handling equipment must be clean and disinfected between each lot of certified seed. Placing seed in storages that have been treated with chlorpropham (CIPC) may result in delayed or irregular sprouting, poor stand, and low yield.
Seed tubers should be stored at 40°F to prevent premature sprouting and dehydration. Tubers should be warmed to 50° to 60°F before being handled and cut. Curing cut seed is best accomplished by placing seed in half-full pallet boxes or spread out in piles only a few feet deep with adequate air circulation, temperature between 55° and 60°F, and about 90 percent relative humidity. After cut seed has been held at optimal curing conditions for one week, the storage temperature should be lowered to between 40° and 45°F to maintain vigor and avoid excessive sprout growth.
For most varieties grown in New York State, seed weight of 1 1/2 to two ounces is optimal. Cut seed should be blocky in shape to reduce the cross-sectional area and facilitate uniform planting by equipment. Mechanical seed cutters should be adjusted to seed size and shape, and seed should be graded to a uniform size before cutting. See Table 24.1.
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| Table 24.1 Potato seed (cwt) required to plant one acre. | |||||||||
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seed in row |
34" between rows |
Weight of seed pieces (oz) |
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Chemical treatment is not a substitute for disease-free seed or good sanitation and handling, but it can reduce losses from disease when cut seed is held before planting or is planted into cold, wet soil. It can also prevent the introduction into noninfested soils of surface-borne organisms that cause diseases such as scab, Rhizoctonia, Verticillium wilt, and blackleg.
Soils should be tested frequently for nutrient levels and pH. Many fields with a long history of potato production have accumulated large amounts of phosphorus and potassium (potash). Excessive levels of potash can depress specific gravity. Low soil pH reduces the availability of phosphorus and increases the availability of toxic elements such as iron and aluminum. To control common scab, soil pH should be kept within a relatively narrow range (5.0 to 5.2). If scab-resistant varieties are used, soil pH levels near 6.0 increase availability of phosphorus and other soil nutrients.
All lime and fertilizer recommendations should be based on soil test history. Mineral soils should have pH determined in calcium chloride and should have measurements made of iron, aluminum, and manganese in addition to the traditional measurements of phosphorus (P), potassium (K), and magnesium (Mg). See Table 24.2 for the recommended application rates of nitrogen, phosphorus, and potassium. If soil magnesium is below 100, apply 50 pounds of MgO per acre (30 lb magnesium per acre).
Cornell cover crop decision tool
See Cornell article on nutrient deficiency symptoms
Go to Cornell Nutrient Analysis Lab website to find out how to get soil samples tested.
Cornell Soil Health website and manual
SARE Publication: "Building Soils for Better Crops"
SARE publication: "Managing Cover Crops Profitably"
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| Table 24.2 Recommended application rate of nutrients based on soil tests. | |||||||||
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N
pounds/acre
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P2O5
pounds/acre
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K2O
pounds/acre
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Comments | ||||||
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Soil
Phosphorus Level
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Soil
Potassium Level
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low
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med.
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high
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low
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med.
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high
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120-175
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240
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180
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120
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240
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120
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75
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Broadcast and disk-in. Sidedress at first cultivation. | |
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75-125
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100
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75
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50
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100
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75
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50
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| 1:
Apply 75-100 lb N/A in bands at planting, then apply
remainder when
plants are 4-8 inches tall. Reduce N rate by 75 lb/A if a
good stand
of clover or alfalfa is plowed down. 2: If pH levels are below 5.2 or iron plus aluminum levels are above 200, apply 240 lb phosphate/A regardless of soil phosphate level. Banded phosphate is more available than broadcast applications. |
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Enhancing Color of Red SkinnedVarieties
To enhance skin color of red skinned varieties, apply 2.3 oz of Riverdale 2,4-D L.V.4 Ester at bud stage. An additional application ten days later is allowable.The color of smooth skinned varieties such as chieftan is intensified by one or two applications. Color enhancement does not occur when 2,4-D is applied to clones with slightly netted skin.
Vine Killing
Chemical vine killing is used to aid in the harvest operation by desiccating potato vines and weeds and conditioning tubers to reduce bruising and skinning during harvest and handling. It also controls tuber size, minimizes incidence of hollow heart, and helps control diseases such as late blight and leafroll. Ideally, chemical vine kill should simulate natural plant death. Rapid plant death can cause vascular discoloration, and in severe cases, the tissue at the stem of the tuber can become sunken and discolored. This affects the outward appearance of the tuber and provides an entry for decay causing organisms. High rates of chemicals, dry soils, and warm temperatures encourage rapid vine kill. Use low rates of chemicals on hot, dry days and higher rates in cool weather. Do not allow vine killers to drift onto neighboring foliage or crops. Under good conditions, the time between vine killing and harvest is ten to 14 days. For specific chemicals and application rates, see Table 24.3.
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| Table 24.3 Vine killing compounds | |||||
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Compound(s) |
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Comparing Environmental Risks of Pesticides |
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Common name |
Rate/A Product |
PHI (days) |
REI (hours) |
Field Use EIQ |
Comments |
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diquat dibromide |
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Reglone
|
1-2 pt |
24
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Do not apply to drought stressed potatoes. Make a second application if necessary to obtain dessication of dense vine growth. A 5 day interval is recommended between applications. Do not exceed a total of 4 pts. per acre. Use a nonionic surfactant. | ||
| glufosinate-ammonium | |||||
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†Rely
|
3 pts | 9 | 12 | 10 | Not for use in Nassau and Suffolk Counties. Do not split application nor apply more than one application. Do not apply to potatoes grown for seed. Plant-back restrictions of 30 to 120 days for various crops. |
†Not for use in Nassau and Suffolk Counties
Facility
Sanitation
Facilities and handling equipment such
as bin pilers should be cleaned and disinfected properly
before potatoes
are placed in storage. See Table
24.4. Bins or
equipment treated with quaternary ammonium compounds must be
rinsed with
drinkable water before coming into contact with potatoes intended for
human consumption. Structural, mechanical, and electrical
problems should
be identified and repaired before the storage area is
filled. Check for
breaks in moisture barriers and insulation to avoid cold spots during
the winter.
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Table 24.4 Disinfectants. |
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| Common name Trade name
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Rate
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Comments
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sodium hypochlorite |
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(Clorox, Lysol, etc.) |
1 gal/10 gal water |
For use on machinery and floors. | |||
Curing and Storage
Cuts and bruises heal most
rapidly under
conditions described previously for precutting seed. High
relative humidity
at 50° to 60°F should
be provided for two to three weeks at the beginning of the
storage period.
After this, the temperature should be gradually lowered to
40°F
for tablestock or seed or maintained at 50°F
for chipstock varieties such as Atlantic or Norchip or at 45°F
for Kanona, Monona, or Snowden. When a condition such as field frost,
late blight, or ring rot that favors decay is present, the
curing period
should be eliminated and the temperature dropped as soon as
possible.
Desired storage temperature is best achieved with forced-air ventilation controlled thermostatically by an air proportioning system. Air flow should be uniform throughout the storage facility to maintain consistent temperature and oxygen levels. Air flow rates early in the storage season may range from a continuous flow of 1/2 to 1 cu. ft./cwt/min. with high relative humidity to enhance the curing process. Later a maintenance program should use an air flow of 1/2 to 4/5 cu. ft./cwt/min. as needed (five to ten percent of the time). If severe rot potential exists, continous air flow rates as high as two cu. ft./cwt/min. may be required to cool and dry the tubers. Excessive air flow rates, however, particularly at low relative humidity, will dehydrate tubers and interfere with the wound healing process. Relative humidity in storage should be as high as possible without causing condensation on the tubers and the storage structure. Good insulation properly protected with a vapor barrier reduces the danger of condensation.
Sprout Inhibitors
Sprout inhibitors should be
used in conjunction
with good storage management. Although most potato varieties
are dormant
for two to three months after harvest, they will eventually
sprout even
in long-term cold storage. Two chemical sprout inhibitors
are available
to lengthen the storage period. Maleic hydrazide is applied as
a field spray on green foliage two to three weeks after the full bloom
stage. This material is translocated to the tubers and helps
prevent sprouting.
Chlorpropham (CIPC) is applied as an aerosol through
the air ventilation
system of the storage facility or as a spray on tubers on the packing
line. For specific application rates, see Table 24.5.
Because the normal warning signal of sprouting will have been
suppressed,
it is important to examine tubers in the center and at the base of the
pile at frequent intervals during the storage season to make sure that
storage rots, internal sprouting, or other disorders are not
developing.
Seed potatoes should not be treated with either material or stored in
buildings where CIPC has been applied.
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| Table 24.5 Sprout inhibitors | |||||
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Compound(s) |
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Comparing Environmental Risks of Pesticides |
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| Common name Trade Name |
Rate/A Product |
PHI (days) |
REI (hours) |
Field Use EIQ |
Comments |
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maleic hydrazide |
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Drexel Sprout Stop
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1-1.33 gal/ 30-150 gal water |
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12
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47
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Apply to growing plants when the smallest tubers are 1.5" in diameter, except for Norchip, which must be at least 2" in diameter. Vines must remain green at least several weeks after application. Allow at least a 2 week interval before use of a vine killer. Do not use on seed potatoes. |
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2 gal/ 30gal water |
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12
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47
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| chlorpropham (CIPC) | |||||
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Sprout Nip |
- |
-
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-
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-
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Apply directly to tubers. Use as a commercially applied aerosol treatment in storage or as an emulsifiable concentrate applied as a spray after washing tubers. Apply after cuts and bruises have healed (2-3 weeks after harvest). Under dosage may increase internal sprouting. Seed potatoes may show delayed sprouting if placed in treated storage, even if all treated potatoes are removed first. Federal law requires that shipping containers are labeled with the chemical name of this inhibitor. |
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Table 24.6
Nonpathogenic disorders. |
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| Disorder |
Management
Option
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Recommendation
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Air pollution |
Variety selection |
Andover and Norland are particularly sensitive varieties. | |||
|
Hollow heart |
Variety
selection |
Varieties
differ in severity. Avoid growing oversized tubers.
Utilize
appropriate plant spacing. Irrigate and fertilizefor specific variety
requirements.
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Internal
necrosis
|
Variety selection |
Varieties differ in susceptibility. Irrigation reduces soil temperatures and increases calcium uptake. | |||
Blackspot |
Maintain tuber turgor |
Minimize impact events during harvesting, transporting, grading, and handling. Store in high humidity and warm before handling operations. | |||
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Secondary
tubers
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Purchase good quality seed and keep in cold storage. | |||
See non-infectious disease fact sheet from Alberta, Canada
See UC Davis post harvest guide for potatoes
See Cornell Report: Food Safety Begins on the Farm
See Cornell "Smart Marketing" series.
See USDA grade standards for fresh potatoes, seed potatoes, processing potatoes, and chipping potatoes
See current wholesale prices from US markets
See "Fresh Now from New York Farms"
SARE Publication: "Marketing Strategies for Farmers and Ranchers"
SARE Publication: "Direct Marketing Resource Guide"
| Seed piece decay
| Seedborne pathogens | Bacterial soft rot | Fusarium dry rot
| Early blight | Late blight
|
| Verticillium wilt | Fusarium wilt | Root rot | Canker
& Black scurf | Botrytis vine rot |
| White mold | Golden nematode
| Potato scab | Bacterial ring rot
|
| Pink rot | Powdery scab | Leak | Silver
scurf |
SARE Publication: "A Whole-Farm Approach to Managing Pests"
|
primarily caused by Fusarium dry rot, Rhizoctonia black scurf, Helmnthosporium silver scurf, common scab, and bacterial soft rot pathogens |
See Cornell fact sheet on detection of tuber diseases in potato
See Cornell fact sheet on Fusarium dry rot
See Cornell fact sheet on Rhizoctonia disease of potato
Time for concern: Plant emergence
Key characteristics:
| Management Option | Recommendation |
| Resistant varieties | No resistant varieties are available. |
| Site selection | Seed planted into warm, well-drained soil will emerge faster. |
| Seed selection/treatment | Seed quality is the most important factor in minimizing losses due to this disease. Plant only certified seed. Carefully inspect seed at the time of receipt. If possible, evaluate the seed before it is shipped. For a guide to potato seed evaluation see Reference 1. Seed treatment is the second most important consideration to optimize stand establishment and early-season growth. Seed should be warmed to 50ÉF before handling, cutting, or planting. New York Certified Seed Potatoes - 2007 Crop Directory |
| Planting | Shallow planting and light cultivation to break up compact soil will increase soil temperature, improve oxygen levels around the seed piece, and speed plant growth. |
| Note(s) | Physiological disorders due to lack of oxygen and cold temperatures during storage or transit contribute to seed piece problems and poor stand establishment. |
| Scouting/thresholds, Crop rotation, Postharvest, and Sanitation |
These are not currently viable management options. |
|
Compound(s) |
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Comparing Environmental Risks of Pesticides |
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| Common name Trade Name |
Rate/A Product |
PHI (days) |
REI (hours) |
Field Use EIQ |
Comments |
| Seed piece treatments | |||||
| fludioxonil + mancozeb | |||||
|
0.5 lb /cwt |
-
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24
|
1-2
|
Use Maxim MZ (Groups 12 + M3) against Rhizoctonia black scurf, silver scurf, black dot, Fusarium and seed piece late blight. Also labeled for use for seed potato production. | |
| flutolanil + mancozeb | |||||
|
Moncoat MZ
|
0.75-1 lb/cwt |
-
|
24
|
<1
|
Use Moncoat MZ (Groups 7 + M3) against Rhizoctonia, Fusarium dry rot and seed piece late blight. |
| mancozeb | |||||
Potato Seed Treater PS |
1-1.33 lb/cwt |
- |
24 |
- |
|
Dithane DF |
1.25 lb/50gal | - |
24 |
- |
Use mancozeb (Group M3) for Fusarium seed piece decay, for seed piece LB movement. |
| 1
lb/cwt |
-
|
24
|
-
|
To control Fusarium seed piece decay. Plant as soon as possible after treatment. | |
| maneb + streptomycin | |||||
| 1 lb/cwt |
-
|
24
|
-
|
Check registration status | |
| imidacloprid + mancozeb | |||||
| Gaucho-MZ | 0.75 lb/cwt | - | 24 | - | Suppression of Fusarium dry rot, Rhizoctonia, and seed piece late blight. Aids in control of aphids, Colorado potato beetle and other insects. |
| imidacloprid + thiophanate-methyl + mancozeb | |||||
| Tops-MZ-Gaucho | 0.75 lb/cwt | - | 24 | - | Tops-MZ-Gaucho (fungicide Groups 1 + M3) has activity towards Rhizoctonia, silver scurf, Fusarium dry rot and seed piece late blight. Aids in control of aphids, Colorado potato beetle, and other insects. |
| thiophanate-methyl + mancozeb + cymoxanil | |||||
| Evolve | 0.75 lb/cw | - | 24 | - | Evolve (Fungicide Groups 1 + M3 + 27) has activity towards Rhizoctonia, silver scurf, Fusarium dry rot and better activity towards seed piece late blight. |
| thiophanate-methyl + mancozeb | |||||
|
Tops MZ |
0.75 lb/cwt |
-
|
24
|
-
|
Tops MZ (Fungicide Groups 1 + M3) has activity towards Rhizoctonia, silver scurf, Fusarium dry rot and seed piece late blight. |
| Trichoderma harzianum | |||||
| T-22 HC | 0.5-2 oz/cwt | - | 0 | - | For suppression of Rhizoctonia black scurf and stem canker. Not effective in cool and wet soils. |
| In furrow treatments | |||||
| azoxystrobin | |||||
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In-furrow |
-
|
4
|
<1
|
Quadris and Amistar (Group 11) are effective for control of Rhizoctonia, silver scurf and black dot. Use higher rate if field location is conductive for disease development or if potatoes are grown on muck soils. | |
|
Amistar
80 WDG
|
0.125-0.25 oz/1000 row feet |
-
|
4
|
<1
|
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| flutolanil | |||||
|
**Moncut 70DF |
0.71-1.1 lb/A |
-
|
12
|
12-19
|
Not for use in Nassau/Suffolk Counties. May leak into ground water. Moncut (Group 7) is used for control of Rhizoctonia stem canker and black scurf. |
| pentachloronitrobenzene (PCNB) | |||||
|
5-10
pts |
-
|
12
|
146-291
|
For Rhizoctonia control, apply in 10-20 gallons of water per acre based on a 34-inch row spacing. Spray an 8.5 inch band into seed furrow at time of planting. | |
|
OLF= Other labeled
formulations. |
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See Cornell fact sheet on detection of tuber diseases in potato
Time for concern: Between harvesting and
marketing
Key characteristics: Bacteria may be present in lenticels, which appear
as tan or water-soaked areas on the tuber surface. Advanced infections will
be seen as soft rot of the tuber flesh. The amount of damage depends on the
population of the bacteria on and in the seed, seed storage and handling practices,
and variety susceptibility. See Reference 1.
| Management Option | Recommendation |
| Resistant varieties | No resistant varieties are available. |
| Site selection | Infection of the lenticels is common in saturated soils. |
| Seed selection/treatment | Plant disease-free seed. New York Certified Seed Potatoes - 2007 Crop Directory |
| Harvest | Avoid injuries to the tuber during harvest. |
| Note(s) | Soft rot bacteria infects through the stolons or through lesions created by other disease organisms or wounds. |
| Postharvest | The use of chlorine wash treatments can prevent the spread of decaying bacteria by killing the organism on contact. See Section 10.1 in the Postharvest Handling chapter. Provide good conditions for wound healing (55É to 60ÉF and 95 percent relative humidity, with good ventilation) for two to three weeks. Following the curing period, temperatures should be kept as low as possible. Do not move potatoes unnecessarily during the storage period because new wounds will be created. Severely affected tuber lots should not be stored. |
| Scouting/thresholds, Crop rotation, and Sanitation |
These are not currently viable management options. |
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Compound(s) |
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Common name |
Rate/A
Product |
Comments
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| chlorine | |||||
|
AgClor 310
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65-125 ppm |
Add
to wash water. The temperature of the water and the
potato should
be close. Follow the label. Water pH should be between
6 and 7.5.
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See Cornell fact sheet on Fusarium dry rot
See Cornell fact sheet on detection of tuber diseases in potato
Time for concern: Planting, harvest, and postharvest
Key characteristics: Symptoms include sunken and shriveled areas on the
surface of the tubers. The rot may extend to the center of the tuber and contain
a fungal growth that is pink, white, or yellow. Affected tissue often becomes
colonized by soft rot bacteria. See References 1 and 2.
| Management Option | Recommendation |
| Scouting/thresholds | Inspect for Fusarium dry rot before pruchasing. If necessary, grade out affected tubers before cutting seed. |
| Note(s) | The Fusarium dry rot pathogens have developed resistence to thiophanate-methyl. |
| Resistant varieties | No resistant varieties are available. |
| Site selection | Plant seed with a Fusarium problem in warm ground and cover with as little soil as practical. |
| Seed selection/treatment | Purchase seed with as little dry rot as possible. Seed becomes more susceptible as the storage season progresses. Warm seed to at least 50ÉF before handling and cutting to minimize injury and promote growth. Bruising the seed during handling spreads the disease. Treat seed with a fungicide. Protect seed from wind and sunlight during planting because dehydration weakens seed. Cut only as much seed as can be planted within 24 hours. Cut with sharp knives and disinfect seed cutting and handling equipment often. Always disinfect between seed lots. Do not mix seed lots. New York Certified Seed Potatoes - 2007 Crop Directory |
| Harvest | Harvest tubers after skins are set and when pulp temperature is greater than 50ÉF. |
| Postharvest | The fungus infects through wounds at harvest. Avoid injuries to the tuber and provide conditions for wound healing in storage (55É to 60ÉF and 95 percent relative humidity with good ventilation) for two to three weeks. Following the curing period, temperatures should be kept as low as possible. Do not move potatoes unnecessarily during storage because new wounds will spread the disease. |
| Crop rotation and Sanitation | These are not currently viable management options. |
|
Compound(s) |
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Comparing Environmental Risks of Pesticides |
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| Common name Trade Name |
Rate/A Product |
PHI (days) |
REI (hours) |
Field Use EIQ |
Comments |
| thiabendazole | |||||
|
Mertect 340-F
3.8 lb/gal |
0.42 fl oz/2000 pounds |
-
|
12
|
<1
|
Apply Mertect (Group 1) uniformly in a fine mist with water to each ton of potatoes as tubers pass over a bin loader. Do not apply to cut tubers. Note: Fusarium resistance makes disease control unpredictable. |
|
|
See Cornell fact sheet on early potato early blight
See Cornell fact sheet on detection of tuber diseases in potato
Organic management of early blight on solanaceous crops
Time for concern: Early to mid-July through harvest
Key characteristics: Leaf lesions are dark brown
and appear leathery with faint, concentric rings giving a "target-spot"
effect. Spots grow to 1/2 inch. Tuber infections appear as small, irregular,
brownish black spots which are usually sunken. The rotted tuber tissue is firm,
hard, and somewhat corky. Tuber infection is much less common than foliar infection.
See References 1, 3, and 4.
| Management Option | Recommendation |
| Scouting/thresholds | Record the occurrence and severity of early blight. No thresholds have been established. NEWA makes daily calculations of P-days. |
| Resistant varieties | Potato varieties differ in their susceptibility to early blight. Onaway is particularly susceptible. |
| Note(s) | Environmental stress such as drought increases plant susceptibility. |
| Crop rotation | Minimum two year rotation without potatoes, tomatoes, or eggplants if severe outbreaks have occurred. Crop rotation and disease management article Cornell cover crop decision tool Cornell Forage Species Selection Tool |
| Seed selection/treatment | Plant disease-free, certified seed. New York Certified Seed Potatoes - 2007 Crop Directory |
| Vine killing | Infection to tubers can be reduced by allowing tubers to mature in the ground for at least two weeks after the vines die. Dig when the vines are dry. |
| Harvest | Avoid wounding during harvest. |
| Sanitation |