See Cornell Report: NEW YORK CERTIFIED SEED POTATOES VARIETY DESCRIPTIONS

New York Certified Seed Potatoes - 2007 Crop Directory

Planting Methods

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.

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.

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 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"

Harvesting

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.

†Not for use in Nassau and Suffolk Counties

Check NYS PIMS (Product, Ingredient, and Manufacturer System) to see if the label is current for New York. SPECIAL NEW YORK RESTRICTIONS MAY APPLY. (http://magritte.psur.cornell.edu/pims/)

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.

Check NYS PIMS (Product, Ingredient, and Manufacturer System) to see if the label is current for New York. SPECIAL NEW YORK RESTRICTIONS MAY APPLY. (http://magritte.psur.cornell.edu/pims/)

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.

Check NYS PIMS (Product, Ingredient, and Manufacturer System) to see if the label is current for New York. SPECIAL NEW YORK RESTRICTIONS MAY APPLY. (http://magritte.psur.cornell.edu/pims/)

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 USDA Marketing site

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"

Disease Management

| 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"

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:

Check NYS PIMS (Product, Ingredient, and Manufacturer System) to see if the label is current for New York. SPECIAL NEW YORK RESTRICTIONS MAY APPLY. (http://magritte.psur.cornell.edu/pims/)

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.

Check NYS PIMS (Product, Ingredient, and Manufacturer System) to see if the label is current for New York. SPECIAL NEW YORK RESTRICTIONS MAY APPLY. (http://magritte.psur.cornell.edu/pims/)

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.

Check NYS PIMS (Product, Ingredient, and Manufacturer System) to see if the label is current for New York. SPECIAL NEW YORK RESTRICTIONS MAY APPLY. (http://magritte.psur.cornell.edu/pims/)

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.