New York Certified Seed Potatoes - 2008 Crop Directory

24.2 Planting Methods

Only certified seed (2008 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 24.2.1.

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.

See Cornell report comparing farm ecosystem and management factors on organic and conventional farms

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 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 24.3.1 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).

Cornell cover crop decision tool

Cornell article: "Closing the phosphorus cycle on vegetable farms: releasing soil-bound phosphorus to support springtime seedling growth."

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"

24.4 Harvesting

24.4.1 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.

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. For specific chemicals and application rates, see Table 24.4.1.

†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/)

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. See Table 24.4.2. 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/)

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. 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 24.4.3. 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 Cornell GAPsNET

See UC Davis post harvest guide for potatoes

See Cornell "Smart Marketing" series

See USDA grade standards for fresh potatoes, seed potatoes, processing potatoes, and chipping potatoes

See USDA Agricultural Marketing Service site

See current wholesale prices from US markets

See Cornell article on a New York Potato Promotion project

SARE Publication: "Marketing Strategies for Farmers and Ranchers"

SARE Publication: "Direct Marketing Resource Guide"

24.5 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 | Nematodes | 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 article on assessing virus resistance in NY potatoes

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.

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 potato late blight

See Cornell fact sheet on late blight of potato and tomato

See Cornell fact sheet on detection of tuber diseases in potato

Organic management of late blight on solanaceous crops

Late Blight Research at Cornell

Time for concern: Throughout the growing season and in storage
Key characteristics: The spores are commonly carried by wind, rain, and equipment. Lesions on leaves and stems become visible as small flecks within three to five days after infection. The infected tissue is initially water-soaked but becomes brown or black in a few days. Lesions are often surrounded by a halo of light green tissue. Under high humidity, sporulation is visible as a delicate, white mold surrounding the lesion. See References 1, 3, and 5.

Late Blight Research at Cornell

See Cornell fact sheet on detection of tuber diseases in potato

Ohio State fact sheet on Fusarium and Verticillium wilts on potato

Organic management of VW on solanaceous crops

Time for concern: Mid-season to harvest
Key characteristics: Wilt symptoms result from the growth of the fungus in the water-conducting tissues of the root and stem. Yellowing, wilting, and defoliation are the first symptoms. These typically occur on one side of a leaf or one side of the plant. When the affected stems are cut diagonally at the base, brown streaks are observed. See Reference 1.

See Cornell fact sheet on detection of tuber diseases in potato

Ohio State fact sheet on Fusarium and Verticillium wilts on potato

Time for concern: Mid-season to harvest
Key characteristics: Symptoms include tuber lesions and vascular discoloration. Wilting and chlorosis of the foliage is similar to Verticillium wilt. Laboratory isolation of the fungus is necessary for positive identification. See Reference 1.

Cornell fact sheet on black dot

Time for concern: Growing season and into storage
Key characteristics: This disease is also referred to as "black dot" because of the numerous black, fungal structures that appear on tubers, stolons, roots, and stems both above- and below ground. Root growth is reduced and appears brown to black in color. Tuber infection appears as brown to gray discoloration over a large part of the tuber surface or as round spots larger than 1/4 inch in diameter. See Reference 7.

*Restricted use only (†) Not for use in Nassau/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/)

See Cornell fact sheet on Rhizoctonia disease of potato

See Cornell fact sheet on detection of tuber diseases in potato

Ohio State fact sheet on Rhizoctonia on potato

Organic management of black scurf on solanaceous crops

Time for concern: Growing season
Key characteristics: This fungus causes a variety of symptoms on tubers including cracking, malformation, and russeting. The black scurf symptom is common. The sclerotia may be flat and superficial or large, irregular, and lumpy. See References 1 and 8.

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/)

Cornell Botrytis fact sheet

Oregon State gray mold ID fact sheet

Time for concern:
Key characteristics: This fungus infects dead tissue and can be seen as a fuzzy, gray growth on dead blossoms or senescent leaves. It is sometimes mistaken for late blight. Under wet conditions and when vine growth is lush, the fungus may move into the stem tissue. The stem rot is initially wet and slimy. The fungus sporulates on infected tissue and produces a dense, gray to off-white growth.

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 bean white mold (same organism)

UMAINE fact sheet on potato white mold

Organic management of white mold on solanaceous crops

Time for concern:
Key characteristics: The fungus is soilborne and generally infects stems at the soil line, but the infection may occur on any part of the plant. Symptoms include dense, cottony, white growth and the production of hard, black, irregularly-shaped sclerotia on infected tissue. This disease is not common on potatoes in New York.

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 potato scab

See Cornell fact sheet on detection of tuber diseases in potato

Cornell PDC fact sheet on potato scab

Organic management of scab on solanaceous crops

Time for concern: Flower to end of season
Key characteristics: The symptoms run from superficial russeting to deep pitting. See References 1 and 9.

See Cornell fact sheet on detection of tuber diseases in potato

Ohio State fact sheet on bacterial ring rot

Time for concern: Seed purchase, planting, throughtout season, and at harvest
Key characteristics: When infected tubers are cut crosswise, a creamy yellow to brown breakdown of the vascular ring is observed. Squeezing the infected tuber causes a cream-colored, cheesy exudate to ooze from the vascular ring. Secondary organisms attack infected tubers in storage and may cause skin cracks and a reddish brown discoloration. See Reference 1.

See Cornell fact sheet on detection of tuber diseases in potato

Ohio State fact sheet on pink rot and leak

Time for concern: Growing season through marketing
Key characteristics: External symptoms appear around the stem end or eyes and lenticels. The infected area turns purple to dark brown with a black band. Tubers become rubbery or spongy and exude a liquid when squeezed. When cut, the infected tissue turns pink in a matter of minutes, then darkens to brown and finally to black. 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 detection of tuber diseases in potato

Time for concern: Cold, wet seasons, growing season through marketing
Key characteristics: Lesions are similar to common scab lesions, but have a powdery texture due to the olive green to brown spore mass produced by the fungus at harvest. Lesions are first visible as purple spots on the tuber surface then as cankers without spore masses. This fungus (protozoan) is the vector for potato Mop Top virus. See Reference 1.

See Cornell fact sheet on detection of tuber diseases in potato

Ohio State fact sheet on pink rot and leak

Time for concern: Harvest
Key characteristics: External symptoms consist of gray to brown lesions with water soaked appearance around wounds or near the stem. A freshly cut affected tuber turns reddish tan, then brown, and finaly black. 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 silver scurf

See Cornell fact sheet on detection of tuber diseases in potato

Time for concern: At planting and through growing season
Key characteristics: Silver scurf infects only the skin of the potato. Symptoms appear at the stolon end as small, pale, brown spots. Severe browning of the surface layers of tubers may occur, followed by sloughing-off of the outer layers of the periderm. Lesions are circular. The silvery appearance of older lesions is most obvious when the tubers are wet. See References 1 and 10.

Time for concern: Before and during planting
Key characteristics: Both the root-knot nematode and the lesion nematode are widespread in New York soils and at high populations can cause significant yield losses for potatoes. Damage from these nematodes is especially high on sandy and organic soils as well as in poor health soils. The populations and damage of lesion nematodes has steadily increased in recent years, probably due to the increase use of grains as cover and rotational crops to improve soil quality and health. In addition, lesion nematode even at low soil population interacts with Verticillium dahliae in causing the early dying disease. Potato serves as a good host for both nematodes and is thus not a desirable host to have in a rotational crop program. The diagnostic symptoms are found on the fine fibrous roots as galls or root thickenings of various sizes. Similarly, above-ground symptoms of potatoes infected with lesion nematodes are of general stunting and infected roots may or may not show brown to black lesions. The presence of nematodes in roots or in soil around roots is the only definitive evidence of their involvement.

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/)

USDA/APHIS Golden nematode information

Time for concern: Throughout the growing season
Key characteristics: This is a regulated pest.

24.6 Insect Management

| Insecticide Resistance Management | Aphids | Colorado potato beetle | Variegated cutworms |
| Subterranean & surface cutworms |European corn borer | Flea beetle | Potato leafhopper |
| Symphylan | Wireworms | Spider mites | Slugs &Snails

SARE Publication: "Manage Insects on Your Farm: A Guide to Ecological Strategies"

SARE Publication: "A Whole-Farm Approach to Managing Pests"

Table 23.6.1 Insecticide Resistance Management
Genetic resistance to insecticides is an inherited change in the sensitivity of a pest population that is reflected in the failure of a product to achieve the expected level of control.  The objective of insecticide resistance management (IRM) is to prevent or delay the onset of resistance or to help regain susceptibility in insect pest populations. In practice, alternations, sequences or rotations of insecticides from different IRM classes (modes of action) reduce selection for resistance in any one class and prolong the effective life of compounds having that mode of action.
Mode of Action	IRM Class	Chemical Class	Chemical Name	Trade Name
Acetyl Cholineesterase Inhibitors	1	Carbamates	carbaryl	Sevin XLR Plus
			carbofuran	†*Furadan 4F
			methomyl	*Lannate LV
			oxamyl	†*Vydate L
		Organophosphates	dimethoate	Dimethoate 400
			ethoprop	†*Mocap
			methamidophos	*Monitor 4
			methyl parathion	*Penncap M
			phorate	†*Thimet 20G
			phosmet	Imidan 70WP
Gaba-Gated Chloride Channel Antagonists	2	Cyclodienes	endosulfan	*Thionex 3EC
Sodium Channel Modulators	3	Pyrethroids	bifenthrin	*Brigade 2EC, *Capture 2EC
			cyfluthrin (beta)	*Baythroid XL, *Renounce 20WP
			cyhalothrin (lambda)	*Warrior II
			esfenvalerate	*Asana XL
			permethrin	*Ambush 25W, *Pounce 25WP
Nicotinic Acetylcholine Receptor Agonists	4	Chloronicotinyl	acetamiprid	Assail
			*imidacloprid	*Admire Pro, *Provado 1.6F, Generic imidacloprid
Nicotinic Acetylcholine Receptor Allosteric Activators	5	Spinosyns	spinosad	Entrust, SpinTor
			Spinetoram	Radiant SC
Chloride Channel Activators	6	Abamectin	abamectin	*Agri-Mek, *Abba
Selective Homopteran Feeding Blocker	9B	Pymetrozine	pymetrozine	Fulfill
	9C	Flonicamid	flonicamid	Beleaf 50 SG
Microbial Disruptors of Insect Midgut Membranes	11	Bacillus thuringiensis	Bt	Novodor
Moulting Disruptor (Dipteran)	17	Cyromazine	cyromazine	Trigard
Voltage Dependent Sodium Channel Blockers	22	Oxadiazines	indoxacarb	Avaunt
Multiple Modes of Action (Mixture of several active ingredients)		Chloronicotinyl and Pyrethroid	imidacloprid cyfluthrin	*Leverage 2.7
Unknown Mode of Action		Azadirachtin	azadirachtin	Ecozin, 3EC, Neemix 4.5
		Bifenazate	bifenazate	Acramite 4SC
		Cryolite	sodium aluminofluoride	Kryocide, Prokil Cryolite 96

See pictures of CPB damage
See pictures of CPB life cycle

Organic management of CPB on solanaceous crops

Time for concern: Late April through vine-kill
Key characteristics: The adults have alternate black and yellowish orange stripes that run lengthwise on the wing covers, five of each color on each wing. The beetles are 3/8 inch long by 1/4 inch wide and convex in shape. The eggs are yellowish orange and deposited in clusters on the underside of leaves. Egg masses contain between 20 and 40 eggs. Larvae are small, humpbacked, and red with two rows of black spots on each side of their body. See Reference 11 and http://www.nysaes.cornell.edu/ent/factsheets/.