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Chapter 24: Potatoes

24.1 Recommended Varieties

Variety1 Skin color2 Maturity3 Use4 GN5 Scab6 Nitrogen required7
Mineral Muck
Andover W ME C, T R MR 150-175 125
Atlantic9 Bu M C R MR 120-150 100
Chieftain R M T S MR 120-150 100
Eva W M T,C R MR 150-175 125
Genesee W L T R MR 120-150 100
Keuka Gold9 Y ML T R R 120-150 100
Lehigh W ML T R R 150-175 125
Marcy Bu L C R MR 100-125 75
Monona W M C, T S MR 150-1758 1258
Norland R E T S R 150-1758 1258
Norwis W ML C, T S VS 120-150 100
Pike9 W ML C R R 120-150 100
Reba W M C, T R MR 120-150 100
Redsen R E T S MR 150-1758 1258
Salem W M T R R 120-150 100
Snowden Bu VL C S MS 120-150 75
Superior Bu ME T S R 150-1758 1258
Yukon Gold Y M T S VS 120-150 100

1: All potato varieties should be considered susceptible to late blight.
2: W = white; Bu = buff white; R = red; RUS = russet; Y = yellow
3: E = early; ME = medium to early; M = medium; ML = medium to late; L = late; VL = very late
4: T = tablestock; C = chipstock
5: R = resistant or S = susceptible to Golden Nematodes (Race Ro1)
6: R = resistant; MR = moderately resistant; MS = moderately susceptible; S = susceptible to scab; or VS = very susceptible
7: Nitrogen recommended in lb/acre
8: Apply no more than 100 lb of N/acre if an early harvest is desired.
9. May have internal necrosis in susceptible production areas.

24.2 Planting Methods

Only certified seed (New York Certified Seed Potatoes - 2017 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.

Table 24.2.1 Potato seed (cwt) required to plant one acre

Distance between
seed in row
34" between rows
Weight of seed pieces (oz)
36" between rows
Weight of seed pieces (oz)
  1 1.5 1.75 2   1 1.5 1.75 2
inches cwt
6 19 29 34 38   18 27 32 37
8 14 22 25 29   14 20 24 27
10 11 17 20 23   11 16 19 22
12 10 14 17 19   9 14 16 18
15 8 11 14 16   7 11 13 14

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.

24.3 Fertility
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 guidelines 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 24.3.1 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).

Table 24.3.1 Recommended application rate of nutrients based on soil tests

N pounds/acre P2O5 pounds/acre   K2O pounds/acre Comments
  Soil Phosphorus Level   Soil Potassium Level  
  low med. high   low med. high very high  
120-175 240 180 120   240 120 75 50 Broadcast and disk-in. Sidedress at first cultivation.
75-125 100 75 50   100 75 50 50  
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.

24.4 Harvesting

24.4.1 Enhancing Color of Red Skinned Varieties

To enhance skin color of red skinned varieties, apply 1.6 fluid ounces per acre in 5 to 25 gallons of water of Riverdale 2,4-D L.V. 6 Ester at the pre-bud stage (plants about 7 to 10 inches high). An additional application 10 to 14 days later is allowable. The color of smooth skinned varieties such as Chieftain is intensified by one or two applications. Color enhancement does not occur when 2,4-D is applied to clones with slightly netted skin. Do not harvest within 45 days of application.

24.4.2 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.

24.4.3 Facility Sanitation

Facilities and handling equipment such as bin pilers should be cleaned and disinfected properly before potatoes are placed in storage. 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.

24.4.4 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, continuous 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.

24.4.5 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. 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.

Table 24.4.4 Nonpathogenic disorders

Disorder Management Option Guideline
Air pollution Variety selection Andover and Norland are particularly sensitive varieties.
Hollow heart Variety selection
Maintain uniform growing conditions.
Varieties differ in severity. Avoid growing oversized tubers. Utilize appropriate plant spacing. Irrigate and fertilize for specific variety requirements.
Internal necrosis Variety selection
Minimize heat stress
Varieties differ in susceptibility. Irrigation reduces soil temperatures and increases calcium uptake.
Blackspot Avoid bruising tubers
Maintain tuber turgor
Minimize impact events during harvesting, transporting, grading, and handling. Store in high humidity and warm before handling operations.
Secondary tubers Avoid old seed Purchase good quality seed and keep in cold storage.

24.5 Disease Management

24.5.1 Seed Piece Decay and Seedborne Pathogens
24.5.2 Bacterial Soft Rot
24.5.3 Fusarium Dry Rot
24.5.4 Early Blight
24.5.5 Late Blight
24.5.6 Verticillium Wilt
24.5.7 Fusarium Wilt
24.5.8 Black Dot Root Rot
24.5.9 Canker and Black Scurf
24.5.10 Botrytis Vine Rot
24.5.11 White Mold
24.5.12 Potato Scab
24.5.13 Bacterial Ring Rot
24.5.14 Pink Rot
24.5.15 Powdery Scab
24.5.16 Leak
24.5.17 Silver Scurf
24.5.18 Nematodes
24.5.19 Golden Nematode

 

24.6 Insect Management

24.6.1 Colorado Potato Beetle
24.6.2 Aphids
24.6.3 Potato Leafhopper
24.6.4: Flea Beetles
24.6.5 Subterranean and Surface Cutworms
24.6.6 Variegated Cutworm
24.6.7 European Corn Borer
24.6.8 Wireworms
24.6.9 Symphylans
24.6.10 Spider Mites
24.6.11 Slugs and Snails

 

24.7 Weed Management

 

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Maintained by Abby Seaman, New York State IPM Program. Last modified 2019.