Crop Profile for White Potatoes in Virginia

Prepared: April, 2003

In 2001, 6,300 acres of summer potatoes were harvested in Virginia.Potato production in Virginia averaged roughly 220 cwt./acre or 22,000 lbs./acre in 2001. A total of 1,386,000 cwt. or 138,600,000 lbs. of fresh market potatoes were produced in Virginia in 2001. The 2001 crop was valued at $9,494,000 or approximately $0.069/lb. Virginia ranked 6th of 12 potato-producing states, accounting for 7.65% of the national potato production in 2001.

Production Regions

A few hundred acres of potatoes are grown in southeastern Virginia, primarily in Chesapeake County and also in the western part of the state. However, most of those produced in Virginia, approximately 4,000 acres, are grown on the Eastern Shore.

Cultural Practices

White-skinned varieties recommended for planting in Virginia include Superior(early season), Atlantic, Reba and Red LaSoda (midseason), and Kennebec and Snowden (late season). Red-skinned varieties include Cherry Red and NorDonna (midseason). Variety selection often depends on the market choice of the grower, either for chipping or fresh. Chipping potatoes are grown only on the Eastern Shore and account for roughly half of the potato production in that region. Fresh market potatoes account for the other half of Eastern Shore production and are also grown throughout the rest of the regions described above.

March 10 to April 5 is the recommended planting time in Virginia for summer potatoes. Before planting, seed potatoes are cut into blocky pieces, which contain at least one eye. Following cutting, pieces should be immediately dusted with the appropriate fungicide (Captan 7.5%, Polyram 7%, Maneb 8%, Tops 2.5%, or Maxim 0.5%) and planted or stored under conditions suitable for rapid healing. Spacing of these pieces in the ground depends on their size and also on the marketing tactics of the finished product. As the aboveground portion of the plant reaches the early bud stage, the underground portion produces tubers or potatoes. Typically this occurs approximately 6-8 weeks after planting.

Soil tests should be taken before planting to aid in soil implement decisions. The target pH for scab-susceptible potatoes is 5.2 and for scab-resistant potatoes it is 6.2. Average fertilizer inputs for both fresh and chipping potatoes include 100 lb. of nitrogen, 200 lb. of phosphorus, and 200 lb. of potassium. Annual soil tests may suggest slightly different values. Approximately two-thirds of the required fertilizer is banded at planting, and the additional one-third is sidedressed at a later date. Generally, potatoes respond well to both fertilization and irrigation. Irrigation is utilized as needed depending on environmental conditions. In addition, potato fields may be cultivated to control small weeds before close-in. The length of maturation varies for chipping vs. fresh market potatoes, with chipping potatoes remaining in the ground longer for higher yields. Both fresh market and chipping potatoes are harvested by machine.Harvesting usually occurs late June to early August.

During the growing season, worker activities in the field could include such things as planting seed potatoes (March-April), cultivating, scouting, spraying, and harvesting (June-August). The workers risk potential exposure to pesticides during these activities and should follow all safety procedures determined by the label, mostly wearing proper personal protective equipment (PPE) and strictly following Re-Entry Intervals (REIs) when returning to the field. Activities that bring workers in direct contact with the plants during the growing season are generally uncommon, as most work performed in the field is done mechanically.

Special Use Labels

Section 18 Emergency Use Exemption and Special Local Needs (24C) labels are used to supplement the chemical tools available to producers for pest control. Once the problem or gap in pest control has been identified, specialists submit the proper documentation for the emergency/special label. Thus far, Extension specialists have been successful in obtaining these labels, which must be applied for annually and are usually only valid for limited time intervals. Without these, pest control in vegetable crops would be extremely difficult for producers.

Insect Pests

Control recommendations found below were modified from information presented in the 2002 Commercial Vegetable Production Recommendations--Virginia[2] unless otherwise noted.

INSECTS

Insect pests of potatoes in Virginia include aboveground foliage-feeders and stalk borers, as well as belowground root and tuber feeders. Overall, the Colorado potato beetle (CPB) is the most important pest. Other pests include aphids, potato leafhopper, European corn borer, potato tuberworm, wireworms, flea beetles, and cutworms. A number of insecticides are labeled for insect control on potatoes, but many are organophosphates or carbamates, and relatively few are effective against CPB. If uses of these insecticide classes were limited or removed, pest control would become even more challenging for potato producers. Details regarding insect pests of potatoes and their management in Virginia can be found below.

Aphids
Green Peach Aphid, Myzus persicae
Melon Aphid, Aphis gossypii
Potato Aphid, Macrosiphum euphorbiae

Several species of aphids infest potatoes in Virginia. Green peach aphid, potato aphid, and melon aphid are the primary three species and are, for the most part, equally abundant in Virginia. Aphids may be present on plants throughout the growing season, but peak infestations often occur in late spring and then again in early fall. Aphids feed on plant sap, which may reduce plant vigor, size, and yield. Also, as they feed on the underside of the leaves, aphids excrete honeydew. This, in turn, leads to the growth of black sooty mold, which may block out sunlight and thus reduce plant yield. Aphids also have the potential to transmit plant viruses. Each of the three species carries a different array of viruses, all of which can be devastating.

Monitoring: Aphids are generally controlled by the insecticides applied for other pests, primarily Colorado potato beetle. Thus, they are not a primary concern for Virginia potato growers. Nonetheless, scouting for aphids is recommended. Large aphid populations may be detected by the appearance of cast skins, sooty mold, or shiny honeydew accumulations on lower foliage. When incidence of aphids appears in the field, examine five fully expanded leaves from each of ten locations in the field. Insecticide treatments are recommended when potato and green peach aphids exceed two aphids/leaf before bloom, four aphids/leaf during bloom, and ten aphids/leaf within two weeks of vine kill, or when melon aphid counts exceed one aphid/leaf before bloom, two aphids/leaf during bloom, and five aphids/leaf within two weeks of vine kill.

Chemical Control: Insecticide applications for Colorado potato beetle or potato leafhopper usually control this pest. See Chemical Insect Control section.

Biological Control: A number of natural enemies such as lady beetles (adults and larvae), lacewing larvae, syrphid larvae, parasitic wasps, and fungal pathogens will reduce aphid populations. Natural enemies will often keep aphid populations below damaging numbers and, therefore, should be considered before an insecticide application. However, if the spread of virus is of concern, chemical treatment will be necessary.

Cultural Control: Many potato cultivars are resistant to plant viruses and should be considered in the pest management decision-making process for aphids. Plant disease-free certified seed. Avoid planting fields immediately downwind of a barrier such as hedgerows or wood lots, which reduce wind velocity and increase the number of dispersing aphids falling into fields. Harvest the crop as soon as possible to avoid late-season aphid colonization.

Colorado Potato Beetle, Leptinotarsa decemlineata

In Virginia, the Colorado potato beetle (CPB) is the most serious pest of potatoes. Adults and larvae feed on the leaves and terminal growth of potatoes, which hinders tuber development and may result in yield loss or possibly plant death. The amount of yield loss depends on the growth stage of the potato plant at infestation. CPB overwinter as adults in the soil and emerge in the spring and feed for a short time before mating and laying eggs. Each female deposits 300-500 yellow eggs on the undersides of plant leaves. Eggs hatch in 4-9 days and larvae feed for three weeks, then drop to the ground and pupate. A new adult generation will then emerge 5-10 days later. There can be three annual generations of CPB in Virginia, but not all the beetles go on to form a third generation. The third generation usually develops on weeds and is often overlooked.

Monitoring: Fields should be sampled weekly beginning at plant emergence. When scouting, at least ten sites should be selected along a V- or W-shaped path throughout a given field. At each site, chose one stem from each of five adjacent plants and count and record all adults, large larvae (more than half-grown), and small larvae (less than half-grown). If more than 50 adults or 75 large larvae or 200 small larvae are counted per 50 stems, treatment is recommended.

Chemical Control: Many currently labeled insecticides on potatoes are no longer effective against CPB because of insecticide resistance development. This varies considerably from state to state. Therefore, it is important to check the results of the latest local efficacy trials. When insecticides are used, proper timing, rates, and good spray coverage are crucial to managing resistance. Rotation of chemicals is also very important. Currently, in Virginia, effective control of CPB can be achieved with imidacloprid (Admire, Provado, Gaucho seed piece-treatment), abamectin (Agri-Mek), thiamethoxam (Actara, Platinum), and spinosad (SpinTor). Bt tenebrionis (Novodor, Raven) will control young larvae but not adults and large larvae. Endosulfan (Thiodan, Phaser) and cryolite (Kryocide, Prokil cryolite) are two older chemistries that are still effective against CPB but are not often used by growers. Imidacloprid is by far the most commonly used insecticide for CPB control.

Biological Control: "New Leaf" white potatoes are available and provide season-long control of CPB. These potatoes have been genetically altered to express Bacillus thuringiensis tenebrionis (Bt) protein that is toxic to CPB. The use of this control tactic has been limited by market acceptability of transgenic crops. Several natural enemies of CPB occur, including egg parasitoids, lady beetles, predatory bugs, and tachinid flies, but they do not normally provide sufficient control. The fungal pathogen Beauveria bassiana has been used for CPB control with moderate success. The pathogen is limited mostly by economics and incompatibilities with fungicides.

Cultural Control: Rotation to non-solanaceous crops - those other than potato, tomato, eggplant and pepper - is extremely important in reducing CPB problems. Also, physical distance between fields containing the previous year's solanaceous crop and the current crop is important for reducing CPB problems. The greater the distance between fields, the longer it takes for colony establishment and thus resistance development. Cultural manipulations such as application of straw mulch increases ground predators and causes decreased numbers of beetles. In addition, proper spray timing is important. For example, avoiding application of late-season sprays will also help prevent the buildup of insecticide-resistant beetles.

Cutworms
Black cutworm, Agrotis ipsilon
Variegated cutworm, Peridroma saucia

Cutworm larvae may be dull gray, brown, or black and may be striped or spotted, depending on species. Another distinguishing quality is their act of rolling into a tight C-shape if disturbed. The two major species attacking potatoes are the variegated cutworm, which feeds on lower leaves and petioles, and the black cutworm, which largely feeds at the soil surface and below on roots/tubers and lower stems, but will occasionally feed on leaves. Both feed at night and can be especially troublesome to tubers where soil cracking occurs. Typically, however, cutworms are not a major concern for potato producers in Virginia.

Monitoring: Cutworm larvae are present during July and August, although they are not typically seen in the open during the day. Digging the soil around injured plants may reveal their presence. If cutworms exceed six/plant or foliar loss is more than 10%, protective sprays should be applied.

Chemical Control: No materials (foliar and systemic) are effective if larvae are not feeding above ground. Several spray applications may be required for control. Insecticides are typically applied to foliage and the soil surface for control. See Chemical Insect Control for options.

Biological Control:No current recommendations for commercial production.

Cultural Control: No current recommendations for commercial production.

European Corn Borer, Ostrinia nubilalis

The European corn borer (ECB) is an annual pest of potatoes, but seldom in populations damaging enough to sufficiently reduce yields in Virginia. ECB overwinters as a mature larva inside stems of numerous crops. They pupate in the spring, emerge as moths, and mate. Following mating, females lay between 500 and 600 eggs in small scale-like masses on the undersides of leaves. As eggs develop, they change color from clear to white to pale yellow to a "blackhead" stage before hatching. After hatch, ECB larvae feed initially on leaf tissue, then bore into potato stems. Stalk tunneling weakens stems and allows the entrance of bacterial and fungal pathogens, causing the stems to further weaken and collapse. Tubers may also be of poor quality or may rot in the presence of disease organisms. Three to four generations of ECB occur each year in Virginia.

Monitoring: Moth activity and relative abundance can be monitored with blacklight or pheromone traps. Eggs can be sampled by visual examination of foliage, but this is a time-consuming and difficult task. In addition, timing is critical because eggs can hatch in 3 to 5 days. Close attention must therefore be paid to the presence of moths at traps. Treatments should typically be applied 7-10 days after moth flight.

Chemical Control: Proper timing of ECB sprays is critical because most insecticides are effective only during the 2- to 3-day period between egg hatch and when larvae bore into stems. Apply the first spray when 10% of the stems have entry holes in fresh market varieties or 25% in processing varieties. Make 2-3 applications on a 5- to 10-day schedule. See Chemical Insect Control section for insecticide options. If a pyrethroid (Ambush 2EC, Asana XL, Baythroid 2E, Pounce3.2EC) is used for ECB control, make first application when 8-10 ECB moths are being trapped in local pheromone or blacklight traps. Apply 2-3 additional applications at 5- to 7-day intervals, based on moth activity.

Biological Control: Many natural enemies of the ECB occur, including lady beetles, minute pirate bugs, parasitoids, and insect pathogens. However, these natural enemies do not provide adequate commercial control of ECB.

Cultural Control:Avoid planting potatoes in fields that have been rotated to corn. If this is impossible, then cut corn stubble as short as possible and shred stalk material. Mowing grasses and weeds will help drive moths away from fields.

Potato Flea Beetle, Epitrix cucumeris

Flea beetles are not of particular concern to potato producers in Virginia. However, if present, they can be devastating, particularly to young plants. These pests may also transmit early blight and bacterial ring rot as they chew plant leaves. Adult flea beetles overwinter in the soil and emerge in the early spring to feed on a variety of crops. Feeding on potato leaves, in the spring, typically results in small round holes. Female adults lay eggs on the soil near the plant base. Larvae hatch in about a week and burrow into the soil, where they feed on roots for 2-3 weeks, then pupate and emerge from the soil as adults. There are approximately two generations per year in Virginia.

Monitoring: Because the beetles are small, mobile, and feed on the undersides of leaves, sampling for leaf damage is the preferred method. No economic thresholds have been developed.

Chemical Control: Insecticide applications for Colorado potato beetle or potato leafhopper usually control this pest. See Chemical Insect Control section.

Biological Control: No effective natural enemies.

Cultural Control: Cultural practices function as a first line of defense against flea beetle infestations. These include: removal/destruction of plant trash or culled potatoes, weed control, and late planting. Plowing after harvest in the fall will serve to remove crop debris and also control weeds.

Potato Leafhopper, Empoasca fabae

After the CPB, potato leafhopper (PLH) is probably the second most serious insect pest for potato producers in Virginia. Both PLH nymphs and adults feed by piercing the undersides of leaves and sucking out the plant sap. These pests also contain a toxin in their saliva that damages photosynthetic tissue and affects the plant?s ability to produce food. Initially, leafhopper feeding results in stippling of the leaf surface followed by rolling and yellowing of leaves and, in severe cases, leaf or plant death. Yield losses may be high with large PLH populations. Damage is typically worse in dry years.

Monitoring: Sampling for PLH is usually done via visual examination of leaves or by sweep net. Monitor fields for potato leafhoppers from early June until early August. Treatment is suggested if leafhopper counts exceed one adult per sweep or one nymph per ten leaves.

Chemical Control: See Chemical Insect Control section for specific recommendations.

Biological Control: Although several natural enemies of PLH occur, their impact on populations is minimal.

Cultural Control: Glandular-haired varieties of potatoes are available that are resistant to PLH.

Potato Tuberworm, Phthorimaea operculella

Historically the potato tuberworm has been a severe pest in potatoes planted in the fall, but in recent years it has not been a problem in Virginia. Tuberworms overwinter as larvae or pupae in the soil or in potatoes that are not subjected to freezing temperatures. Five generations can occur in Virginia. Moths emerge in the spring, mate, and then the females lay their eggs either on rough surfaces around potato eyes or on the lower leaf surfaces. Larvae hatch, feed, and mature in 7-10 days under ideal summer conditions or longer under cooler temperatures. The tuberworm larvae can cause damage by mining the leaves and by boring into the tubers of potato. Foliage infestations result in gray, papery blotches, which become brownish and brittle and are usually concentrated on older, lower leaves. Tuber feeding renders the potatoes completely unmarketable. Larvae moving from the foliage access the tubers when they are near the surface of the ground by moving through cracks in the soil or shortly after they have been dug and are exposed to the air. As tuberworms feed they tunnel through the potato, leaving behind excrement and webbing on which disease-causing fungi may grow and cause further problems.

Monitoring: Pheromone traps are effective for monitoring moth activity.

Chemical Control: See Chemical Insect Control section for recommendations.

Biological Control: A number of parasitoids attack the eggs and larvae. Predators are less important.

Cultural Control: Cultural practices are usually effective in controlling tuberworms if done in a timely manner. Some of these include destroying cull potatoes, cultivating or irrigating to prevent deep cracks in the soil, keeping adequate soil coverage on the potatoes, harvesting potatoes soon after maturing, and removing them from the field immediately. After harvesting the potatoes, store them at the proper temperature and screen the storage areas for egg-laying moths. Also, avoiding planting of infested seed pieces, covering newly dug potatoes with vines, and leaving piles of potatoes out overnight when egg-laying moths are active will help to further protect against tuberworm infestations.[3]

Wireworms
Corn Wireworm, Melanotus communis
Tobacco wireworm, Conoderus vespertinus

In Virginia, wireworms are the third largest pest problem for growers. Damage as a result of these insects typically occurs in fields or crop rotations favoring their development. Potatoes planted in weedy fallow fields or following potatoes, corn, and small grain cover crops are especially at risk. The two most common species attacking potatoes in Virginia include the corn wireworm and tobacco wireworm. Wireworm lifecycles are variable. Some species can spend from 3 to 6 years as larvae in the soil. Adults, otherwise known as click beetles, are active in mid- to late summer and lay their eggs in the soil among the roots of grasses. Larvae emerge and begin feeding on seed pieces, roots, and developing shoots. Larvae burrow deep in the soil when temperatures drop below 50°F and surface again in the spring after soils warm. Full development can take up to six years. Wireworm feeding holes can make plants more susceptible to fungal infection and other diseases.

Monitoring: Wireworms can be monitored in the spring or fall by sampling the soil with a shovel or auger and sifting for larvae, or by baiting. Baits consist of corn and wheat buried a few inches in the soil and covered with black plastic. After two weeks, the baits are examined for presence of larvae. Sampling is used for determining presence or absence of the pest. If wireworms are detected, a control measure is recommended.

Chemical Control: See Chemical Insect Control section for recommendations.

Biological Control: No effective natural enemies occur.

Cultural Control: Cultural practices for wireworm control includes plowing, crop rotation, and planting in well-drained areas. Plowing helps to dry out the soil and also to destroy the pupal chambers, larvae, and adults. Crop rotation, especially with more tolerant plants, will help limit wireworm population buildup. In addition, wireworms seem to favor areas with high soil moisture, so planting into well-drained areas should reduce environmental suitability.

Chemical Insect Control

The list below contains products available to producers for insect control in white potatoes along with the recommended application rates. Use estimates are also included based on anecdotal data.[4]

• abamectin (Agri-Mek 0.15EC) - PHI-14 days. Avermectin. Apply at a rate of 0.01-0.02 lb. a.i./A for control of CPB. Do NOT exceed 0.04 total a.i./A/season. Do NOT make more than two sequential applications. REI-12 hours. Used on 5% of acreage for control of CPB.
• azadirachtin (Aza-Direct, Azatin, Ecozin, Neemix) - PHI-0 days. Botanical. Apply at a rate of 0.02-0.04 lb. a.i./A when CPB first appear and are in their early larval stages. REI - 12 hours. Used on <1% of acreage for control of CPB.
• azinphos-methyl (Guthion 2L) - PHI-7 days. Organophosphate. Apply at a rate of 0.38 lb. a.i./A for control of CPB. Apply at a rate of 0.50 lb. a.i./A for ECP and potato tuberworm control and 0.50-0.75 lb. a.i./A for control of flea beetles and leafhoppers. REI - 5 days. Not currently used in Virginia.
• Bacillus thuringiensis (various formulations) - PHI-0 days. Microbial. Bt tenebrionis formulations effective ONLY on small CPB larvae. Make first application when eggs begin to hatch and repeat applications at 5- to 7-day intervals if small larvae are present. If rainfall occurs within 24 hours post-treatment, reapplication may be necessary. REI - 4 days. Used on 5% of acreage for control of CPB.
• carbaryl (Sevin 80S, Sevin Bait) - PHI-0 days. Carbamate. Apply at a rate of 2.0 lb. a.i./A for control of cutworms. REI - 12 hours. Used on <1% of acreage for control of cutworms.
• carbofuran (Furadan 4F) - PHI-14 days. Carbamate. Apply at a rate of 0.5-1.0 lb. a.i./A for control of ECB. Do NOT exceed eight applications per acre per season. REI - 48 hours. Used on 10% of acreage for control of ECB.
• cryolite (Kryocide, Prokil cryolite) - PHI-0 days. Inorganic fluorine. Apply at a rate of 9.6-11.5 lb. a.i./A for CPB control. Do NOT apply more than 92 lbs. a.i./A/season. A copy of the label must be in the possession of user at time of application. REI - 12 hours. Not currently used in Virginia.
• cyfluthrin (Baythroid 2E) - PHI-0 days. Pyrethroid. Apply at a rate 0.01-0.04 lb. a.i./A for control of flea beetles and leafhoppers, a rate of 0.01-0.03 for control of cutworms, a rate of 0.02-0.04 for control of potato tuberworm, and a rate of 0.03-0.04 lb. a.i./A for control of ECB. Do NOT exceed 0.26 total lb. a.i./A/season. REI - 12 hours. Used on 12% of acreage for control of PLH, ECB, and flea beetles.
• diazinon (Diazinon 14G) - PHI-at plant. Organophosphate. For control of wireworm, broadcast and incorporate into soil just before planting at a rate of 3.0-4.0 lb. a.i./A. REI - 12/24 hours. Used on 15% of acreage for control of wireworms.
• dimethoate (Dimethoate 4EC) - PHI-0 days. Organophosphate. Apply at a rate of 0.25-0.5 lb. a.i./A for POA, GPA and leafhopper control. REI - 48 hours. Used on 40% of acreage for control of PLH.
• disulfoton (Di-Syston 15G) - PHI-75 days. Organophosphate. For control of wireworm, flea beetles, and leafhoppers, broadcast at a rate of 2.0-3.1 lb. a.i./A and work into soil 2-3 inches or apply a similar rate at planting. If needed, an additional application may be sidedressed after plants become established. Do NOT make more than 2 applications per season (in-furrow or broadcast pre-plant and a sidedress). REI - 48 hours. Used on 10% of acreage for control of wireworm.
• endosulfan (Thiodan 3EC, Phaser) - PHI-1 day. Cyclodiene. Apply at a rate of 0.5-1.0 lb. a.i./A for control of CPB, flea beetles, and leafhoppers and at a rate of 0.5-1.0 lb. a.i./A for control of POA and GPA. Do NOT apply more than six times per season. Do NOT exceed 12.0 lb. a.i./A/season. REI - 48 hours. Not currently used in Virginia.
• esfenvalerate (Asana XL 0.66EC) - PHI-7 days. Pyrethroid. Apply at a rate of 0.03-0.05 lb. a.i./A for control of cutworms, ECB, flea beetles, leafhoppers, and potato tuberworm. Do NOT exceed 0.35 lb. a.i./A/season. REI - 12 hours. Used on 10% of acreage.
• ethroprop (Mocap 10G) - PHI-at plant. Organophosphate. Broadcast and incorporate just before planting at a rate of 4.0-6.0 lb. a.i./A or apply at planting at a rate of 3.0 lb. a.i./A for wireworm control. REI - 48 hours. Used on 20% of acreage for control of wireworms.
• imidacloprid (Gaucho seed-piece treatment, Admire 2FS) - PHI-at plant. (Provado 1.6F) - PHI-7 days. Chloronicotinyl. Apply Admire 2FS at a rate of 0.01-0.02 lb. a.i./1,000 row ft. pre-plant or at planting for control of CPB, POA, GPA, melon aphid, flea beetles, and leafhoppers. Apply Provado 1.6F at a rate of 0.05 lb. a.i./A for control of CPB, PLH, POA, GPA, and melon aphid ONLY IF Admire 2F was NOT used at planting. Do NOT exceed 0.31 lbs. a.i./A/year, regardless of application method or formulation. For crops not on the label, a 12-month plant-back interval must be observed. REI - 12 hours. Used on 90% of the acreage.
• methamidophos (Monitor 4EC) - PHI-14 days. Organophosphate. Apply at a rate of 0.75-1.0 lb. a.i./A for control of ECB, POA, and GPA and at 0.50-0.75 lb. a.i./A for control of potato tuberworm. REI - 48 hours. Used on >1% of acreage for control of ECB.
• methomyl (Lannate LV) - PHI-6 days. Organophosphate. Apply at a rate of 0.45-0.90 lb. a.i./A for control of cutworms, POA, GPA, melon aphid, potato tuberworm, flea beetles, and leafhoppers. REI - 48 hours. Used on 5% of acreage.
• methyl parathion (Penncap-M 2FM) - PHI-5 days. Organophosphate. Apply at a rate of 0.5-1.0 lb. a.i./A for control of ECB. REI - 48 hours. Used on <1% of acreage.
• oxamyl (Vydate L 2L) - PHI-7 days. Carbamate. Apply at a rate of 0.25-1.0 lb. a.i./A for control of CPB, wireworms, flea beetles, and leafhoppers and at a rate of 0.5-1.0 lb. a.i./A for control of POA and GPA. REI - 48 hours. Used on 5% of acreage.
• permethrin (Ambush 2EC, Pounce 3.2EC) - PHI-7 days. Pyrethroid. Apply Ambush 2EC at a rate of 0.05-0.20 lb. a.i./A and Pounce 3.2EC at a rate of 0.1-0.2 lb. a.i./A for control of cutworms (Pounce 3.2EC ONLY), POA, GPA, potato tuberworm, flea beetles, and leafhoppers. REI - 24 hours. Used on 30% off acreage for control of PLH and ECB.
• phorate (Thimet 15G) - PHI-90 days. Organophosphate. Apply 2.25 lb. a.i./1,000 ft of row at planting for control of wireworm. REI - 48 hours. Used on 10% of acreage for control of wireworms.
• phosmet (Imidan 50WP) - PHI-7 days. Organophosphate. Apply at a rate of 1.0 lb. a.i./A for control of CPB, flea beetles, and leafhoppers. REI - 24 hours. Used on <1% of acreage.
• pymetrozine (Fulfill 50WP) - PHI-14 days. Pyridine azomethine. Apply at a rate of 0.085 lb. a.i./A for control of POA, GPA, and melon aphid. Do NOT exceed 0.17 total lb. a.i./A/season. REI - 12 hours. Used on <1% of acreage for control of aphids.
• spinosad (SpinTor 2SC) - PHI-7 days. Spinosyn. Apply at a rate of 0.05-0.09 lb. a.i./A for control of CPB and ECB. Do NOT apply more than 0.33 total lb. a.i./A/season. REI - 12 hours. Used on 5% of acreage.
• thiamethoxam (Platinum 2SG, Actara 25WDG) - PHI-30 days. Chloronicotinoid. Apply at a rate of 0.079-0.125 lb. a.i./A for control of CPB, flea beetles, and aphids. Do NOT apply more than 0.125 lb. total lb. a.i./A/season. REI - 12 hours. Used on 15% of acreage.

• azoxystrobin (Quadris 2.1F) - PHI - 14 days. Strobilurins. For control of early blight, apply at a rate of 0.10-0.20 lb. a.i./A. For control of late blight, apply at a rate of 0.20-0.25 lb. a.i./A and only if protectant fungicides have been used before disease occurrence. Do NOT make more than 6 applications of Quadris flowable per acre per year for all diseases. REI - 4 hours.
• chlorothalonil (Bravo, Echo, Equus) - PHI - 0 days. Substituted aromatics. For control of early blight and late blight, apply at a rate of 0.75-1.13 lbs. a.i./A. REI - 12 hours. Apply Bravo Zn for control of early blight at a rate of 0.75-1.10 lbs. a.i./A. REI - 48 hours.
• copper, fixed (various formulations) - Inorganic. PHI - 0 days. For control of early blight, apply at a rate of 0.92 lb. a.i./A. REI - 24 hours.
• cymoxanil (Curzate 60DF) - PHI - 14 days. Acetamides. For control of late blight, apply at a rate of 0.02 lbs. a.i./A (use only in combination with a protectant fungicide; e.g., chlorothalonil or mancozeb). REI - 12 hours.
• dimethomorph (Acrobat MZ 60WP) - PHI - 14 days. Morpholines. For control of late blight, apply at a rate of 1.6 lb. a.i./A and only if protectant fungicides have been used before disease occurrence. Do NOT make more than 5 applications in any one season. REI - 24 hours.
• iprodione (Rovral 50WP) - PHI - 14 days. Dicarboximides. For the control of white mold, apply at a rate of 1.0 lb. a.i./A immediately before row closing, and repeat 28 days later. Apply at a rate of 0.5-1.0 lb. a.i./A for control of early blight. Do NOT irrigate for 24 hours after application. A maximum of 4 applications can be made per season. REI - 12 hours.
• mancozeb (Dithane, Manex II, Manzate, Penncozeb) - PHI - 14 days. Dithiocarbamates. For control of early blight, apply at a rate of 1.2-1.6 lbs. a.i./A and apply at a rate of 1.13-1.50 lb. a.i./A for control of late blight. Do NOT apply more than a total of 14 pounds of mancozeb or Polyram per acre per crop. REI - 12,24 hours. (Gavel) - PHI ?14 days. For control of late blight, apply at a rate of 1.13-1.50 lb. a.i./A and only if protectant fungicides have been used before disease occurrence. Do NOT make more than 6 applications or apply more than 12 lbs. in one season. REI - 48 hours.
• mefenoxam/chlorothalonil (Ridomil Gold Bravo, Fluoronil) - PHI - 7 days. Phenylamides. For control of leak and/or pink rot, apply a rate of 1.52 lb. a.i./A. REI - 48 hours.
• metam-sodium (Busan, Vapam HL) - PHI - N/A Dithiocarbamates. For the control of verticullium wilt, apply the fungicide through center-pivot irrigation in the fall to fallow fields at a rate of 158 lb. a.i./A. REI - 48 hours.
• metiram (Polyram 80DF) - PHI - 14 days. Dithiocarbamates. For the control of early blight and/or late blight, apply at a rate of 1.6 lb. a.i./A. Do NOT apply more than a total of 14 pounds of mancozeb or Polyram per acre per crop. REI - 24 hours.
• propamocarb hydrochloride (Previcur Flex) - PHI - 14 days. For the control of late blight, apply at a rate of 0.50-0.70-0.90 lbs. a.i./A. Rates listed in order for low-medium-high disease risk situations. Use only in combination with a protectant fungicide; e.g., chlorothalonil or mancozeb. REI - 12 hours.
• triphenyltin hydroxide (Super Tin 4L) - PHI - 21 days. Organotins. For the control of early blight, apply at a rate of 0.20 lb. a.i./A plus mancozeb (Dithane, Manax II, Manzate, Penncozeb) at a rate of 1.60 lb. a.i./A. REI - 24, 48 hours.

• clethodim (Select 2EC): PHI - 30 days. Cyclohexanediones. Apply at a rate of 0.094-0.125 lb. a.i./A with oil concentrate to be 1% of the spray solution (1 gallon per 100 gallons of spray solution) postemergence to control many annual and certain perennial grasses, including annual bluegrass. Select 2EC will not consistently control goosegrass. The use of oil concentrate may increase the risk of crop injury when hot or humid conditions prevail. To reduce the risk of crop injury, omit additives or switch to nonionic surfactant when grasses are small and soil moisture is adequate. Control may be reduced if grasses are large or if hot, dry weather or drought conditions occur. For best results, treat annual grasses when they are actively growing and before tillers are present. Repeated applications may be needed to control certain perennial grasses. Yellow nutsedge, wild onion, or broadleaf weeds will not be controlled. Do NOT tank-mix with or apply within 2 or 3 days of any other pesticides unless labeled, as the risk of crop injury may be increased or reduced control of grasses may result. REI - 24 hours. Estimated acres treated - 1%.
• EPTC (Eptam 7E): PHI - 45 days. Thiocarbamates. Apply 3.0-4.5 lb. a.i./A just before planting and disking. This treatment is best for early-season control of nutsedge and other weeds, but on plantings before April 1, it may reduce early vigor and yields slightly. Incorporate into soil in one or two cultivations with a spiketooth harrow or similar piece of equipment. Apply the same amount just before first or second cultivation. This treatment is best for late-season control of nutsedge and other weeds. Primarily controls annual grasses, yellow nutsedge, and a few broadleaf weeds. Use linuron or metribuzin according to recommendations after planting to increase the spectrum of broadleaf weeds controlled. REI - 12 hours. Estimated acres treated - 2%.
• glyphosate (Roundup Ultra Max 4SC, Touchdown, Glyphomax Plus): Phosphono amino acids. Apply 1.50-3.75 lb. acid equivalent/A in the fall after harvest to control perennial grasses and broadleaf weeds, including quack-grass, field bindweed, Canada thistle, and others. Delay application after harvest to allow for adequate weed re-growth to intercept the spray. Apply before frost to weeds with cold-sensitive foliage. Do NOT till or mow for 1 week after application. Consult the label for additional details and the rate to use for each weed species. REI - 4-12 hours. Estimated acres treated - no in-crop applications.
• linuron (Lorox 50DF): PHI - apply before potato emergence. Ureas. Apply 0.40-1.0 lb. a.i./A after planting or before potatoes emerge, but after final drag-off and before grasses are 2 inches tall and broadleaf weeds are six inches tall. Primarily controls broadleaf weeds. Tank-mix with Dual Magnum or Prowl, or use in addition to Eptam for preemergence annual grass control. Use lower rates if tank-mixed. Do NOT plant to crops not on the label for 4 months after treatment. REI - 24 hours. Estimated acres treated - 5%.
• metribuzin (Sencor/Lexone75DF): PHI - 60 days. Triazinones. Apply 0.38-0.50 lb. a.i./A just before emergence. If drag-off is practiced, then the application should be made after drag-off. Primarily controls broadleaf weeds. Tank-mix with Dual Magnum or Prowl, or use in addition to Eptam for pre-emergence annual grass control. Read label for rotation crop restrictions. NOTE: Pre-emergence application to Atlantic and Norland or to any early maturing, smooth, white- or red-skinned potato varieties may cause crop injury, especially under adverse weather conditions and when higher labeled rates are used. REI - 12 hours
• (Lexone/Sencor 75DF): PHI - 60 days. Apply 0.25-0.50 lb. a.i./A before weeds are 1 inch tall. Primarily controls broadleaf weeds. Apply only if there have been at least three successive sunny days before application. Do NOT use on red-skinned or early maturing, smooth, white-skinned varieties. Treatment may cause some yellowing or minor burn. Read label for soil texture, crop rotation, and variety restrictions. REI - 24 hours. Estimated acres treated - 95%.
• paraquat (Gramoxone Max 3SC): PHI - 3 days. Bipyridyliums. Apply at a rate of 0.60 lb. a.i./A as a broadcast spray after the last harvest. Add nonionic surfactant according to the labeled instructions. See the label for additional information and warnings. REI - 24 hours. Estimated acres treated - 1%.
• pendimethalin (Prowl 4EC): PHI - 60 days. Dinitroanilines. Apply 0.50-1.5 lb. a.i./A before potatoes emerge. Prowl primarily controls certain broadleaf weeds, including velvetleaf and early-season annual grasses, but does not control yellow nutsedge. Combine with Lorox to improve velvetleaf control, or with linuron or metribuzin to improve the control of most other broadleaf weeds. REI - 24 hours. Estimated acres treated - 1%.
• rimsulfuron (Matrix 25DF): PHI - 60 days. Sulfonylureas. Apply at a rate of 0.02 lb. a.i./A early postemergence to control many weeds, including foxtail species, pigweed species, wild mustard, and wild radish. Common lambsquarter, common ragweed, jimsonweed, morningglorry species, and yellow nutsedge may only be suppressed. Tank-mix with reduced rates of metribuzin, following label instructions, to increase the spectrum of weeds controlled. Repeat the application 2 to 4 weeks after the initial spray to improve the suppression or control of common purslane and perennial weeds, such as field and hedge bindweed. Results may be most effective when used following a pre-emergence residual weed-control program. Add nonionic surfactant to be 0.25% of the spray solution (1 quart per 100 gallons of spray solution) to improve weed control. Do NOT exceed 2 ounces of Matrix 25DF per acre per year. Rimsulfuron, an ALS inhibitor, blocks acetolactate synthase, effecting cell division at the root tips. Herbicides in this class have a single site of action in susceptible plants. Always use in combination with other herbicides with a different site of action in the plant to prevent the development of resistant weed populations. Read and follow label cautions and resistance management recommendations. REI - 4 hours. Estimated acres treated - 15%.
• sethoxydim (Poast 1.5EC): PHI - 30 days. Cyclohexanediones Apply at a rate of 0.20-0.40 lb. a.i./A with oil concentrate to be 1% of the spray solution postemergence to control annual grasses and certain perennial grasses. The use of oil concentrates may increase the risk of crop injury when hot or humid conditions prevail. To reduce the risk of crop injury, omit additives or switch to nonionic surfactant when grasses are small and soil moisture is adequate. Control may be reduced if grasses are large or if hot, dry weather or drought conditions occur. For best results, treat annual grasses when they are actively growing and before tillers are present. Repeated applications may be needed to control certain perennial grasses. Yellow nutsedge, wild onion, or broadleaf weeds will not be controlled. Do NOT tank-mix with or apply within 2 to 3 days of any other pesticide unless labeled, as the risk of crop injury may be increased, or reduced control of grasses may result. Observe a minimum preharvest interval of 30 days and apply no more than 5 pints per acre in one season. REI - 12 hours. Estimated acres treated - 5%.
• s -metolachlor (Dual Magnum 7.62E or Dual II Magnum 7.64E): PHI - 40 days. Chloroacetamides. Apply 0.96-1.91 lb. a.i./A Dual Magnum or Dual II Magnum before potatoes emerge, but after final drag-off. Primarily controls annual grasses. Nutsedge (nutgrass, coffeegrass) control may be adequate if weed pressure is light. Tank-mix Dual Magnum with linuron or metribuzin for broadleaf control. Apply 1.60 lb. a.i./A Dual Magnum as a directed spray after hilling/at lay-by to provide pre-emergence control of sensitive weeds for the remainder of the growing season. Emerged weeds will not be controlled. This treatment may be applied in addition to a previous (drag-off) application of Dual Magnum or Dual II Magnum, but do NOT apply more than 3.6 pints Dual Magnum per acre in one season. REI - 24 hours. Estimated acres treated - 95%.

• diquat (Diquat 2SC) - PHI - 7 days. Bipyridyliums. Apply at a rate of 0.25 lb. a.i./A in 20-100 gallons of water. Add a nonionic surfactant to be 0.25% of the spray solution. Repeat after 5 days if needed. Do NOT graze livestock in treated areas. REI - 24 hours.
• endothall (Desicate II) - PHI - 10-14 days. Phthalic acids. Apply at a rate of 0.75-1.0 lb. a.i./A in combination with ammonium sulfate and a surfactant. Higher rates are necessary for cool and cloudy conditions. Do NOT use less than 5 or more than 40 gallons of water per acre. Do NOT graze livestock in treated areas. REI - 48 hours.
• paraquat (Gramoxone Extra 2.5SC) - PHI - 3 days. Bipyridyliums. Apply at a rate of 0.30-0.60 lb. a.i./A with 50-100 gallons of water. Do NOT use on vigorously growing vines if potatoes are to be stored or used for seed. Do NOT graze livestock in treated areas. REI - 24 hours.