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Potato is a cool season crop that produces best yields when temperatures average slightly below 70°F during the growing season. Potatoes will grow well on a wide range of soils and are especially well suited for New England. The best soil for potatoes is a well-drained, reasonably deep loam. Potatoes produced on light, sandy, loam soils generally have a more desirable shape and a brighter skin color than those grown on heavier clay-type soils. Poorly-drained soils favor disease development and may result in reduced plant stands, low yields and poor quality. VarietiesEarly Maturing Midseason Late Maturing Spacing and SeedingPlant only certified or foundation seed. Certified and foundation seed has met specific conditions for production practices and disease tolerances. Planting good seed is an essential step to producing a high-quality crop. AMOUNT (CWT.) OF SEED REQUIRED TO PLANT ONE ACRE
The more uniform in size and weight the seed being planted, the more accurate the planter will perform. The ideal seedbed for planting potatoes is warm, medium field capacity in moisture content, and of uniform texture allowing good soil air movement. Soil temperatures should be 50°F to 60°F in order to encourage cut seed wound healing and rapid growth. Do not plant cut seed in soil below 45°F as seed piece decay will be encouraged. SUGGESTED SEED SPACING
Close spacing in the row, 6” to 8”, aids in reducing tuber size and increases the number of tubers set. Using close spacing can reduce the occurrence of hollow heart and growth cracks. Seed pieces should be planted 2” to 4” below the soil level; this will reduce problems with sunburned tubers. For rapid emergence, no more than 2” of soil should cover the seed piece after planting. Where seed is planted deeper than 2”, drag-off, or the removal of the excess soil from the top of the hill, may be employed to encourage rapid emergence. Rapid emergence should be encouraged to reduce problems with soil-borne diseases such as rhizoctonia. Green SproutingThe practice of pre-sprouting seed potatoes is called green sprouting or chitting. This practice accelerates plant emergence and speeds the development of marketable tubers. Many times it gains the producer as much as seven to 10 days in having marketable tubers. This practice is often combined with close plant spacing (about 6”). The tubers are harvested when small and often sold in quart baskets. Consumers usually cook the tubers in their skins.The basic technique is rather simple: About six weeks prior to planting, spread the seed tubers in open-top crates, boxes or flats, one layer deep with the eyes up. Egg cartons for small seed lots work great. The flats are then kept in a warm place (approximately 70°F.) where light levels are medium intensity (bright shade). Direct sunlight is not recommended. The warmth stimulates the development of strong sprouts, which in the presence of light, will remain short and stout and will not easily be broken off during the planting process. Ideally the sprouts will be about 1” in length. Do not cut the seed before green sprouting. Cutting seed pieces prior to green sprouting will encourage desiccation and reduce seed quality LimeLime and fertilizer rates should be applied relative to soil test results and the potato cultivar to be planted. If the cultivar to be raised is common scab resistant, soil pH should be maintained at pH 6.0. This will facilitate not only potato growth but also rotation crops. If the cultivar to be raised is common scab susceptible, then the soil pH should be maintained at pH 5.0 to 5.2. Growers should be aware that acid scab, a scab organism that is active at low soil pH, is found in some areas; in these situations, soil pH should be raised to pH 6.0 and a scab resistant cultivar utilizedFertilizerNitrogen is the most critical element from the standpoint of yield and quality. Excessive nitrogen can delay maturity, decrease quality and adversely affect fry color for processing crops. Too little nitrogen will reduce yields. On most varieties, the amount of nitrogen per acre is usually 140 to 150 pounds. Higher rates can be used on late-maturing varieties such as Russet Burbank and slightly less on early-maturing varieties such as Kennebec. Apply P and K according to soil test results.
Cultivation and HillingHilling and cultivation operations are suggested to begin after the plants begin to emerge and should be completed prior to the plants filling half of the row, so as to not cause foliar or root damage. Hilling allows the use of a shallow planting depth to speed plant emergence, while providing the soil depth necessary later in the season for proper tuber development and protection from sunlight and adverse temperatures. Discs, rolling cultivators, hilling listers or implements with winged cultivator teeth may be used. For best results, hills should be flat and broad rather than narrow and peaked. Cultivation during hilling aids in mechanical weed control and some soil-applied herbicides can be incorporated at this timeSprout InhibitorsSprout inhibitors should be used only in conjunction with good storage management. Federal law requires that shipping containers carrying potatoes treated with postharvest sprout inhibitors be labeled with the chemical name of the inhibitor. When small bags are shipped in master containers, only the master container needs to be labeled. Do not treat seed potatoes.Field Application: Apply 3 lb. a.i. Maleic Hydrazide/A to healthy green non-water-stressed potato vines. Apply when most of the tubers of Russet Burbanks are 4 to 6 oz in weight and Round White varieties are 13/4” to 2” in diameter. Apply at least two weeks before application of any vine killer. If rain comes within 24 hours of application, effectiveness will be reduced. Do not apply at temperatures above 85°F. See label for additional information. Postharvest Application: Bulk storage equipped with good ventilation through the pile or pallet box storages can be treated with chloro-IPC by licensed custom applicators, however, only after harvest cuts and bruises have healed (two to three weeks after harvest). Low doses can increase internal sprouting. Seed potatoes should not be placed in treated storage at any time. Chloro-IPC is sold as an aerosol treatment to be applied in storage or as an emulsifiable concentrate to be added to wash water for prevention of sprouting in marketing channels. Do not use the herbicide formulation for sprout control. Vine DesiccationThorough coverage is important for all these products as they are contact herbicides. Field observations suggest the following ranking of desiccants in terms of speed of stem desiccation: paraquat > diquat > glufosinate > endothall (paraquat being the fastest and endothall the slowest). This implies that the risk of stem end discoloration is greater with paraquat than with the other vine desiccants.Note: ALWAYS FOLLOW LABEL INSTRUCTIONS. The information provided here is based on product labels at the time of writing. If there is any discrepancy between the label and the information below, follow label instructions. The current label for any given product is “the law” regarding its application. Also the products listed here are based on what is currently labeled for use in the state of Maine — these products may or may not be approved for use in other jurisdictions. diquat (Reglone): 1 to 2 pt/A (7 dh, REI 12h). Suitable for seed and storage. Always use a spray adjuvant (0.1 to 0.5% v/v NIS). Rainfast in 30 minutes. A second application may be made depending on density of vine growth. A five-day interval is recommended between applications and not more than 4 pt/A may be applied in one season. Minimum spray volume of 20 gal/A. endothall (Desicate II): is no longer manufactured. glufosinate-ammonium (Rely): 3 pt/A (9 dh, REI 12h). NOT for seed. This is the same active ingredient as Liberty herbicide. Rainfast in four hours. Minimum spray volume of 20 gal/A. NOTE: paraquat (Gramoxone) is no longer registered as a vine dessicant. sulfuric acid (93%): 17 to 26 gal/A (5 dh, REI 5 days). Dangerous to handle. CORROSIVE. Will damage skin and eyes on contact. Specialized equipment required for application. Application may be repeated after five days if vines are not completely desiccated. HarvestPremature harvesting can result in reduced yields and lower specific gravity. On the other hand, if harvesting is delayed too long, field frost and diseases can cause serious losses. Proper operation of the harvesting equipment and careful handling can reduce the amount of damage from bruising. Potatoes should not be allowed to fall more than 4” to 6” and all equipment surfaces should be padded. If potatoes are harvested at temperatures below 55°F, considerable bruising is likely to occur. If tubers are harvested during hot weather (above 80°F) and they cool off slowly, the likelihood of storage rot is increased. The ideal temperature during harvest is 60°F to 70°F. Information on bruise testing is available from the University of Maine Cooperative Extension. StorageAn important aspect of potato pest control is to provide a pathogen-free storage environment. All storage and potato handing equipment surfaces should be thoroughly cleaned and disinfected prior to handling and placing the crop into storage. Surfaces should be well moistened by the disinfectant spray. Spray bin walls until there is a slight runoff. Recommended disinfectants are quaternary ammonium compounds such as Hyamine 2389. Read label for suitability. Bins or equipment treated with quaternary compounds must be rinsed with clean water before coming into contact with potatoes to be used for human consumption.Pre-storage Fungicide TreatmentTreatment of potatoes (seed and tablestock) with thiabendazole (Mertect 340F) as they go into storage has produced excellent control of fusarium tuber rot in storage. The chemical should be applied uniformly in a fine mist or fog as tubers pass over a roller table or bin loader. The rolling motion will facilitate even coverage. To each ton of potatoes, apply 0.42 ounce of Mertect 340F in sufficient water to provide coverage. Do not saturate the tubers.Healing of cuts and bruises is most rapid at high relative humidity (95%) with a tuber temperature of 50°F to 60°F and adequate through the pile ventilation. This temperature should be provided for two to three weeks at the beginning of the storage period. This process is called suberization. Effective suberization will reduce evaporative weight loss and prevent rot organisms from entering damaged tubers. After suberization the temperature should be lowered gradually to 40°F for tablestock or seed or maintained at 50°F for chip stock varieties. When a rot potential such as field frost, late blight or ring rot is present, the curing period should be eliminated, the temperature dropped and the ventilation increased. The crop should be utilized as soon as possible. Temperature control is best achieved with forced air ventilation that is controlled thermostatically by an air proportioning system. Air flows should not exceed 1.0 cu ft/cwt/min. Storage relative humidity should be as high as possible without causing condensation on the storage walls and ceilings. Good insulation properly protected with a vapor barrier reduces danger of condensation. Weed ControlWeed maps of field areas are extremely helpful in planning weed control strategies. A weed map can illustrate problem areas so that growers can target specific problems in specific areas. A weed map can also indicate shifts in weed pressure if kept continuously over years and indicate the possible need for a strategy change. NOTE: For the herbicides listed below, one product trade name and formulation is provided for each active ingredient (common name) as an example of rates, days to harvest (dh), REI, and special instructions. In many cases there are other products available with the same active ingredient. Please see Table 17 and Alphabetical Listing by Trade Name for more information on products with the same active ingredients. Preplant and Stale Seedbed Application glyphosate (Roundup 4S): 1 to 5 qt/A (REI 12h, Group 9). Apply either before field preparation to control emerged perennial weeds or as a replacement to the drag-off operation as described above. Must be applied either before planting or before potatoes emerge; any crop contact will cause crop death. See also Stale Seedbed Technique. Preplant Incorporated and Preemergence Control of Annual Grasses and Certain Broadleaf WeedsEPTC (Eptam 7E): 4 1/2 to 7 pt/A (45 dh, REI 12h, Group 8). Use the higher rate for control of yellow nutsedge and quackgrass. “Superior” potatoes are sensitive to Eptam and, under stress conditions, early season stunting may occur. Apply to loose mellow-moist or drier soil. Incorporate to a depth of 2” to 3” within 20 minutes after application. Drag-off, if used, must occur prior to application and incorporation. May also be applied and incorporated after a clean cultivation as a directed spray to the base of emerged potato plants. Preemergence and Early Postemergence Control of Many Broadleaf Weedslinuron (Lorox DF): 1 1/2 to 4 lb/A (REI 24h, Group 7) in 40 to 100 gal water. Make a single application as a broadcast spray after planting but before crop emerges. Drag-off, if used, must occur prior to application. Do not spray over top of emerged potatoes. Plant seed at least 2” deep. Constant tank agitation is required. See label to select proper rate for your soil type. Heavy rain after application may cause injury to potatoes. Do not repeat application or plant other crops within four months of treatment. Do not overlap spray. Needs moist soil to activate. Will also control small emerged annual weeds if present at the time of application. One pt nonionic surfactant/25 gal spray mixture may be added to improve activity on emerged weeds (see label). May be tank mixed with metolachlor (Dual) or pendimethalin (Prowl) to improve activity on annual grasses. Postemergence Weed Controlclethodim (Select 2 EC): 6 to 8 oz/A (30 dh, REI 24h, Group 1). Apply to actively growing grasses. See label for grass height and herbicide rate. Always use a crop oil concentrate at a rate of 1 gal/100 gal spray mix. See both container label and supplemental label available from dealer. Problem WeedsSee the relative susceptibility chart of weeds to herbicides at the end of this manual to better assess the performance of an individual herbicide on each weed species. Insect ControlRegular field scouting is one of the most important aspects of effective insect control. See Potato Production in the Northeast: A Guide to IPM, UMass pub#C-178. NOTE: For the insecticides listed below, one product trade name and formulation is provided for each active ingredient (common name) as an example of rates, days to harvest (dh), REI, and special instructions. In many cases there are other products available with the same active ingredient. Please see Table 20 and Alphabetical Listing by Trade Name for more information on products with the same active ingredients. AphidsGreen peach, melon or potato aphid may occur in potato, colonizing fields from mid June through July. See Pepper from more details on green peach aphid and Cucumber for more details on melon aphid. Potato aphid is the largest aphid of the three, 3-4 mm long, and may be pink or green. Cornicles are the same as the body color with dark tips. Plants of the rose family serve as alternate hosts to potato aphid in fall and spring. A wide range of weeds, field crops and vegetable crops are hosts in summer. In potato they feed first in young growing tips, spreading downward into older leaves. Injury includes leaf deformity and dieback. Fields should be scouted for aphids starting in late June. Examine aphids/leaf on 50 fully grown compound leaves (5 leaves at ten locations in the field) from top, middle and bottom of the canopy. In fresh market and processing potato, the thresholds for insecticide application is when an average of five aphids per leaf are present, or 10 per leaf within two weeks of vine kill. In Maine, the economic threshold for tablestock and processing fields is when aphids are found on 50 percent of the plants or one winged aphid is found within the field. clothianidin (Belay): 1.9 to 2.8 oz/A (for foliar application), 7.2 to 12 oz/A (furrow or side-dress) (14 dh, REI 12h, Group 4A). Toxic to bees exposed to treatment and for more than 5 days following treatment. Do not use foliar spray after a soil application. Soil application may be at planting or as a side-dress at ground-crack during hilling (cover with at least 3" of soil). dimethoate (Dimethoate 4EC): 8 to 16 oz/A (0 dh, REI 48h, Group 1B). endosulfan (Thionex* 50W): 1 to 2 lb/A (1 dh, REI 24h, Group 2A). flonicamid (Beleaf 50SG): 2 to 2.8 dry oz/A (7 dh, REI 12, Group 9C). insecticidal soap (M-Pede): 1.25 to 2.5 oz/gal water (0 dh, REI 12h). Spray to wet all infested plant surfaces. Repeated applications may be required. Apply with companion aphicide. OMRI listed. malathion (Malathion 57EC): 1 to 1 1/2 pt/A (0 dh, REI 12h, Group 1B). methamidophos (Monitor* 4): 1 1/2 to 2 pt/A (14 dh, REI 4d, Group 1B). Does not control melon aphid (MA). spirotetramat (Movento): 4-5 oz/A (7 dh, REI 24 h, Group 23). Immature stages; may also reduce adult fertility. thiamethoxam (Actara): 3 oz/A (14 dh, REI 12h, Group 4). Foliar spray. Colorado Potato Beetle (CPB)Colorado potato beetles (CPB) are 1/2” long by 3/8” wide, oval with a rounded back, and each forewing is yellow with five black stripes. CPB overwinters in the adult stage, primarily in soil (up to 12 inches deep) in the woods and brushy borders next to host crops, though some burrow into soil in the field. In spring the beetles search for food plants by walking from the field edges. Heavy feeding may occur on edges on non-rotated fields. If beetles do not find host plants via walking they will fly in search of food. Wherever possible, growers should rotate classes of insecticides and avoid using the same chemistry more than once per year, or better, once every other year. Do not use the same chemical class on successive generations in the same year. There are enough different classes to allow this, if you plan carefully. Note the resistance group number of each insecticides and avoid using chemistries from the same group. Use newer chemistries first. Action Thresholds
abamectin (AgriMek* 0.15EC): 8 to 16 oz/A (14 dh, REI 12h, Group 6). Make first application at 50% egg hatch. Do not make more than 2 applications per crop. acetamiprid (Assail 30SG): 1.5 to 4 oz/A (7 dh, REI 12h, Group 4). For resistance management, use a nicotinoid (group 4) insecticide on only one generation every other year. azadirachtin (Neemix 4.5): 7 to 16 oz/A (0 dh, REI 12h, Group 18). Insect growth regulator for small larvae. OMRI listed. Beauveria bassiana (Mycotrol O): 16 to 32 oz/A (0 dh, REI 4h, Group 22). Treat when populations are low and thoroughly cover foliage. Takes 7 to 10 days after the first spray to see control. Repeat applications may be needed. May be tank mixed with Bacillus thuringiensis tenebrionis. OMRI listed. beta-cyfluthrin (Baythroid* XL): 1.6 to 2.8 oz/A (0 dh, REI 12h, Group 3A). chlorantraniliprole (Coragen): 3.5 to 5 oz/A (14 dh, REI 4h, Group 28). May be applied through overhead sprinkler irrigation. clothianidin (Belay): 1.9 to 2.8 oz/A (for foliar application), 7.2 to 12 oz/A (furrow or side-dress) (14 dh, REI 12h, Group 4A). Toxic to bees exposed to treatment and for more than 5 days following treatment. Do not use foliar spray after a soil application. Soil application may be at planting or as a side-dress at ground-crack during hilling (cover with at least 3" of soil). cryolite (Kryocide): 10 to 12 lb/A (0 dh, REI 12h, Group 9B). Not effective against the adult beetle. DO NOT apply more than 96 lb/A per season. Application to exposed tubers may result in excess residues. This material can cause extensive wear of nozzles. cyromazine (Trigard): 2.66 to 5.32 dry oz/A (7 dh, REI 12h, Group, 17). Insect growth regulator for small larvae just after egg hatch. Does not control adult beetles. Low rate will provide suppression only. deltamethrin (Decis* 1.5EC): 1.5 to 2.4 oz/A (3 dh, REI 12h, Group 3A).dinotefuran (Venom 20SG): 7 dry oz/A foliar or 1.4 to 1.65 lbs/A soil (7 dh foliar, REI 12h, Group 4A). For resistance management purposes, do not use foliar spray after soil application or following another nicotinoid (Group 4A) insecticide application on the same crop. For resistance management, use a nicotinoid (Group 4A) insecticide on only one generation every other year. endosulfan (Thionex* 50W): 1 to 2 lb/A (1 dh, REI 24h, Group 2A).esfenvalerate (Asana* XL): 5.8 to 9.6 oz/A (7 dh, REI 12h, Group 3A). imidacloprid (Admire Pro): 0.17 to 0.35 oz/100 lb seed or 3.5 to 7 oz/A (seed treatment), 5.7 to 8.7 oz/A furrow or banded application (REI 12h, Group 4A). Resistance to this material has developed in some potato growing regions of New England. Where it is still effective, prevent resistance development by restricting its use to lands where the beetle has routinely been a major problem, and by using a nicotinoid (Group 4A) insecticide on only one generation every other year. DO NOT use two years in a row on the same lands. See plant-back restrictions on label. Does not control European corn borer. imidacloprid + mancozeb (Gaucho MZ): 0.5 to 0.75 lb/100 lb seed-pieces (REI 24h, Group 4A). Systemic seed-piece treatment. Do not make subsequent application of another nicotinoid (Group 4A) insecticide following a seed-piece treatment. Aids in control of CPB. Not registered in CT or VT. imidacloprid (Provado 1.6F): 3.8 oz/A (7 dh, REI 12, Group 4A). Resistance to this material has developed in some potato growing regions of New England. Where it is still effective, prevent resistance development by avoiding use of a Provado foliar application following another nicotinoid (Group 4A) insecticide application on the same crop. For resistance management, use a nicotinoid (Group 4A) insecticide on only one generation every other year. Moderately effective against aphids and leafhopper. See plant-back restrictions on label. indoxacarb (Avaunt): 3.5 to 6 oz/A (7 dh, REI 12h, Group 22). Efficacy may be improved by the addition of piperonyl butoxide (PBO). lambda-cyhalothrin (Warrior*): 2.5 to 3.8 oz/A (14 dh, REI 24h, Group 3A). methamidophos (Monitor* 4): 1 1/2 to 2 pt/A (14 dh, REI 4d, Group 1B). novaluron (Rimon 0.83EC): 9 to 12 oz/A (14 dh, REI 12h, Group 16B). No more than two applications per season. Insect growth regulator. Best used on early instars. No activity against adult CPB or beneficials. oxamyl (Vydate* L): 1 to 4 pt/A (7 dh, REI 48h, Group 1A). Use when air temperature is greater than 80°F. permethrin (Pounce* 25WP): 6.4 to 12.8 oz/A (14 dh, REI 12h, Group 3A). phorate (Thimet* 20G): 8.5 to 11.3 oz/1,000 row feet for sandy soils, 13 to 17.3 oz/1,000 ft. row in heavy or clay soils (90 dh, REI 48h, Group 1B). On sandy soils, may also be applied 4 to 6 weeks after planting. Distribute granules in the furrow or band on each side of the row. Early-season only. pyrethrin (PyGanic EC5.0): 4.5 to 18 oz/A (0 dh, REI 12h, Group 3A). OMRI listed. pyrethrins + piperonyl butoxide (Pyrenone): 1 tsp/gal, or 1 to 12 oz/A (0 dh, REI 12h, Group 3A). spinetoram (Radiant SC): 6 to 8 oz/A (1 dh, REI 4h, Group 5). For resistance management, do not use a Group 5 insecticide (spinosad or spinetoram) more than once per year. spinosad (Entrust): 1 to 2 oz/A (7dh, REI 4h, Group 5). Controls adult and larvae. For resistance management, do not use a Group 5 insecticide (spinosad or spinetoram) more than once per year. OMRI listed. thiamethoxam (Actara): 1.5 to 3 oz/A (14 dh, REI 12h, Group 4). Foliar spray. For resistance management, use nicotinoid insecticides (Group 4) on only one generation every other year. thiamethoxam (Cruiser 5FS): 0.11 to 0.16 fl. oz/100 lbs of seed (REI 12h, Group 4). See rates based on row spacing on label. Systemic seed treatment. For early-season protection from CPB. For resistance management, use a nicotinoid (Group 4) insecticide on only one generation every other year. thiamethoxam (Platinum): 5 to 8 oz/A (30 dh, REI 12h, Group 4). Systemic insecticide applied to seed pieces in-furrow during planting, impregnated on dry granular fertilizer, or as directed spray at plant emergence or during last hilling operation. Must incorporate into root zone with sufficient irrigation within 24 hours. DO NOT apply as a foliar spray. For resistance management, use a nicotinoid (Group 4) insecticide on only one generation every other year. zeta-cypermethrin (Mustang*): 3.4 to 4.3 oz/A (1 dh, REI 12h, Group 3A). CutwormsCaterpillars hide under the soil surface adjacent to the plant stem during the day and feed after dark. Larvae may feed on leaves, cut stems or even occasionally feed on tubers. For best results, make application between midnight and dawn while cutworms are feeding aboveground. Synthetic pyrethroids (Group 3A) may work best during cool spring weather. See cutworms in the Pepper and Tomato (Outdoor) sections for more information on the black and variegated cutworms.Bacillus thuringiensis aizawai (XenTari): 0.5 to 1.5 lb/A (0 dh, REI 4h, Group 11). Must be ingested; apply in evening before larvae are actively feeding and direct sprays to base of stem. Use high rate at cool temperatures. OMRI listed. carbaryl (10% Sevin Granules): 20 lb/A (3 dh fresh, 21 dh dry, REI 12h, Group 1A). Apply evenly over soil surface. deltamethrin (Decis* 1.5EC): 1 to 2.4 oz/A (3 dh, REI 12h, Group 3A). esfenvalerate (Asana* XL): 5.8 to 9.6 oz/A (7 dh, REI 12h, Group 3A). lambda-cyhalothrin (Warrior*): 1.9 to 3.2 oz/A (14 dh, REI 24h, Group 3A). methamidophos (Monitor* 4): 1 1/2 to 2 pt/A (14 dh, REI 4d, Group 1B). methomyl (Lannate* LV): 24 oz/A (6 dh, REI 48h, Group 1A). Variegated cutworm only. permethrin (Pounce* 25WP): 6.4 to 12.8 oz/A (14 dh, REI 12h, Group 3A). pyrethrins + piperonyl butoxide (Pyrenone): 1 tsp/gal, or 1 to 12 oz/A (0 dh, REI 12h, Group 3A). zeta-cypermethrin (Mustang*): 1.4 to 4.3 oz/A (1 dh, REI 12h, Group 3A). European Corn BorerLarvae infest potato stems but rarely cause yield reductions. Higher levels of stem infestations have been associated with a higher incidence of blackleg. For more information on ECB, see the sweet corn section. beta-cyfluthrin (Baythroid* XL): 1.6 to 2.8 oz/A (0 dh, REI 12h, Group 3A). chlorantraniliprole (Coragen): 3.5 to 5 oz/A (14 dh, REI 4h, Group 28). May be applied through overhead sprinkler irrigation. deltamethrin (Decis* 1.5EC): 1.5 to 2.4 oz/A (3 dh, REI 12h, Group 3A). endosulfan (Thionex* 50W): 1.5 to 2 lb/A (1 dh, REI 24h, Group 2A). esfenvalerate (Asana* XL): 5.8 to 9.6 oz/A (7 dh, REI 12h, Group 3A). indoxacarb (Avaunt): 3.5 to 6 oz/A (7 dh, REI 12h, Group 22). lambda-cyhalothrin (Warrior*): 2.5 to 3.8 oz/A (14 dh, REI 24h, Group 3A). methamidophos (Monitor* 4): 1 1/2 to 2 pt/A (14 dh, REI 4d, Group 1B). novaluron (Rimon 0.83EC): 9 to 12 oz/A (14 dh, REI 12h, Group 16B). No more than two applications per season. Insect growth regulator. permethrin (Pounce* 25WP): 6.4 to 12.8 oz/A (14 dh, REI 12h, Group 3A). pyrethrin (PyGanic EC5.0): 4.5 to 18 oz/A (0 dh, REI 12h, Group 3A). OMRI listed. pyrethrins + piperonyl butoxide (Pyrenone): 1 tsp/gal, or 1 to 12 oz/A (0 dh, REI 12h, Group 3A). spinetoram (Radiant SC): 6 to 8 oz/A (1 dh, REI 4h, Group 5). spinosad (Entrust): 1 to 2 oz/A (7 dh, REI 4h, Group 5). OMRI listed. zeta-cypermethrin (Mustang*): 1.9 to 4.3 oz/A (1 dh, REI 12h, Group 3A). Flea BeetlesShiny black beetles less than 1/8” long. Adults spend the winter under plant residue along tree lines or in the field. In the early spring they feed on solanaceous weeds until they move to potato or other solanaceous crops. Numerous tiny feeding “shot holes” can injure leaves and stunt young plants. Management practices include clean cultivation, crop rotation, delayed plantings, removing or avoiding spring weed hosts, use of row covers, and applying spot treatments targeting young potato plants along the field edges. Full size plants rarely require treatment for flea beetles. Most insecticides registered to control CPB, including spinosad, will control FB. Sweep young plants 25 times and spot treat potatoes along field edges if 50 beetles are found in the sweep net. acetamiprid (Assail 30SG): 1.5 to 2.5 oz/A (7 dh, REI 12h, Group 4). beta-cyfluthrin (Baythroid* XL): 1.6 to 2.8 oz/A (0 dh, REI 12h, Group 3A). carbaryl (Sevin XLR Plus): 1/2 to 1 qt/A (7 dh, REI 12h, Group 1A). clothianidin (Belay): 1.9 to 2.8 oz/A (for foliar application), 7.2 to 12 oz/A (furrow or side-dress) (14 dh, REI 12h, Group 4A). Toxic to bees exposed to treatment and for more than 5 days following treatment. Do not use foliar spray after a soil application. Soil application may be at planting or as a side-dress at ground-crack during hilling (cover with at least 3" of soil). deltamethrin (Decis* 1.5EC): 1.5 to 2.4 oz/A (3 dh, REI 12h, Group 3A). dinotefuran (Venom 20SG): 7 dry oz/A foliar or 1.4 to 1.65 lbs/A soil (7 dh foliar, REI 12h, Group 4A). For resistance management purposes, do not use foliar spray after soil application or following another nicotinoid (Group 4A) insecticide application on the same crop. endosulfan (Thionex* 50W): 1 to 2 lb/A (1 dh, REI 24h, Group 2A). esfenvalerate (Asana* XL): 5.8 to 9.6 oz/A (7 dh, REI 12h, Group 3A). Apply when temperature is less than 80°F and when foliage is free from dew or other moisture. imidacloprid (Admire Pro): 0.17 to 0.35 oz/100 lb seed or 3.5 to 7 oz/A (seed piece treatment), 5.7 to 8.7 furrow or banded application (REI 12h, Group 4A). Do not make subsequent application of nicotinoid (Group 4A) insecticide following a seed-piece treatment. imidacloprid + mancozeb (Gaucho MZ): 0.5 to 0.75 lb/100 lb seed-pieces (REI 24h, Groups 4A & M3). Systemic seed-piece treatment. Do not make subsequent application of another nicotinoid (Group 4A) insecticide following a seed-piece treatment. Aids in control of flea beetles. Not registered in CT or VT. imidacloprid (Provado 1.6F): 3.8 oz/A (7 dh, REI 12h, Group 4A). For resistance management purposes, do not use a Provado foliar application following another nicotinoid (Group 4A) insecticide application on the same crop. See plant-back restrictions. kaolin (Surround WP): 25 to 50 lb/A or 0.25 to 0.5 lb/gal (0 dh, REI 4h). Suppression and repellence only. Follow label instructions for mixing. Generally compatible as a tank mix with other insecticides. OMRI listed. lambda-cyhalothrin (Warrior*): 2.5 to 3.8 oz/A (14 dh, REI 24h, Group 3A). methamidophos (Monitor* 4): 1 1/2 to 2 pt/A (14 dh, REI 4d, Group 1B). methomyl (Lannate* LV): 24 oz/A (6 dh, REI 48h, Group 1A). oxamyl (Vydate* L): 1 to 2 qt/A (7 dh, REI 48h, Group 1A). permethrin (Pounce* 25WP): 6.4 to 12.8 oz/A (14 dh, REI 12h, Group 3A). phorate (Thimet* 20G): 8.5 to 11.3 oz/1,000 row feet for sandy soils, 13 to 17.3 oz/1,000 ft. row in heavy or clay soils (90 dh, REI 48h, Group 1B). Distribute granules in the furrow or band on each side of the row. For larvae and reduction of adults. pyrethrin (PyGanic EC5.0): 4.5 to 18 oz/A (0 dh, REI 12h, Group 3A). OMRI listed. pyrethrins + piperonyl butoxide (Pyrenone): 1 tsp/gal, or 1 to 12 oz/A (0 dh, REI 12h, Group 3A). thiamethoxam (Actara): 1.5 to 3 oz/A (14 dh, REI 12h, Group 4). Foliar spray. thiamethoxam (Cruiser 5FS): 0.11 to 0.16 fl oz/100 lb seed (REI 12h, Group 4). See rates based on row spacing on label. Systemic seed treatment. For early season control. thiamethoxam (Platinum): 5 to 8 oz/A (30 dh, REI 12h, Group 4). Systemic insecticide applied to seed pieces in-furrow during planting, impregnated on dry granular fertilizer, or as directed spray at plant emergence or during last hilling operation. Must incorporate into root zone with sufficient irrigation within 24 hours. DO NOT apply as a foliar spray. zeta-cypermethrin (Mustang*): 1.9 to 4.3 oz/A (1 dh, REI 12h, Group 3A). Potato LeafhopperPotato leafhoppers overwinter in Louisiana and vicinity and move north on storm fronts into the central states and then into New England on winds from the west. Low levels of leafhopper feeding can severely damage plants and cause symptoms known as hopper burn. Leaves yellow, turn brown and die. Adults are light green, 1/8” long, and wedge-shaped, while nymphs are bright green, flatter and fatter than adults, and move sideways in a crab-like fashion. Sample with sweep net and treat if more than one adult per sweep is found. Nymphs can be monitored by visually inspecting lower leaf surfaces on lower leaves. Treat if more than 15 nymphs are found per 50 leaves.acetamiprid (Assail 30SG): 1.5 to 4 oz/A (7 dh, REI 12h, Group 4). azadirachtin (Neemix 4.5): 7 to 16 oz/A (0 dh, REI 12h, Group 18). For nymphs only. OMRI listed. beta-cyfluthrin (Baythroid* XL): 0.8 to 1.6 oz/A (0 dh, REI 12h, Group 3A). carbaryl (Sevin XLR Plus): 1/2 to 1 qt/A (7 dh, REI 12h, Group 1A). clothianidin (Belay): 1.9 to 2.8 oz/A (for foliar application), 7.2 to 12 oz/A (furrow or side-dress) (14 dh, REI 12h, Group 4A). Toxic to bees exposed to treatment and for more than 5 days following treatment. Do not use foliar spray after a soil application. Soil application may be at planting or as a side-dress at ground-crack during hilling (cover with at least 3" of soil). deltamethrin (Decis* 1.5EC): 1.5 to 2.4 oz/A (3 dh, REI 12h, Group 3A). dimethoate (Dimethoate 4EC): 8 to 16 oz/A (0 dh, REI 48h, Group 1B). dinotefuran (Venom 20SG): 7 dry oz/A foliar or 1.4 to 1.65 lbs/A soil (7 dh foliar, REI 12h, Group 4A). For resistance management purposes, do not use foliar spray after soil application or following another nicotinoid (Group 4A) insecticide application on the same crop. endosulfan (Thionex* 50W): 1 to 2 lb/A (1 dh, REI 24h, Group 2A). esfenvalerate (Asana * XL): 2.9 to 9.6 oz/A (7 dh, REI 12h, Group 3A). imidacloprid (Admire Pro): 0.17 to 0.35 oz/100 lb seed or 3.5 to 7 oz/A (seed piece treatment), 5.7 to 8.7 furrow or banded application (REI 12h, Group 4A). Do not make subsequent application of nicotinoid (Group 4A) insecticide following a seed-piece treatment. imidacloprid + mancozeb (Gaucho MZ): 0.5 to 0.75 lb/100 lb seed-pieces (REI 24h, Groups 4A & M3). Systemic seed-piece treatment. Do not make subsequent application of another nicotinoid (Group 4) insecticide following a seed-piece treatment. Aids in control of leafhoppers. Not registered in CT or VT. imidacloprid (Provado 1.6F): 3.8 oz/A (7 dh, REI 12h, Group 4A). For resistance management purposes, do not use a Provado foliar application following another nicotinoid (Group 4A) insecticide application on the same crop. See plant-back restrictions. kaolin (Surround WP): 25 to 50 lb/A or 0.25 to 0.5 lb/gal (0 dh, REI 4h). Suppression and repellence only. Follow label instructions for mixing. Generally compatible as a tank mix with other insecticides. OMRI listed. lambda-cyhalothrin (Warrior*): 1.9 to 3.2 oz/A (14 dh, REI 24h, Group 3A). malathion (Malathion 57EC): 1 to 1 1/2 pt/A (0 dh, REI 12h, Group 1B). methamidophos (Monitor* 4): 1 1/2 to 2 pt/A (14 dh, REI 4d, Group 1B). methomyl (Lannate* LV): 24 to 48 oz/A (6 dh, REI 48h, Group 1A). oxamyl (Vydate* L): 1 to 2 qt/A (7 dh, REI 48h, Group 1A). Repeat at 5- to 7-day intervals. See label restrictions. permethrin (Pounce* 25WP): 6.4 to 12.8 oz/A (14 dh, REI 12h, Group 3A). phorate (Thimet* 20G): 8.5 to 11.3 oz/1,000 row feet for sandy soils, 13 to 17.3 oz/1,000 ft. row in heavy or clay soils (90 dh, REI 48h, Group 1B). On sandy soils, may also be applied 4 to 6 weeks after planting. Distribute granules in the furrow or band on each side of the row. pyrethrin (PyGanic EC 5.0): 4.5 to 18 oz/A (0 dh, REI 12h, Group 3A). OMRI listed. pyrethrins + piperonyl butoxide (Pyrenone): 1 tsp/gal, or 1 to 12 oz/A (0 dh, REI 12h, Group 3A). sodium tetraborohydrate decahydrate (Prev-AM): 100 oz/100 gal (0.5 dh, REI 12h, Group 25). Do not apply in midday sun or mix with copper, sulfur or oils. CT only. thiamethoxam (Actara): 1.5 to 3 oz/A (14 dh, REI 12h, Group 4). Foliar spray. thiamethoxam (Cruiser 5FS): 0.11 to 0.16 fl oz/100 lb seed (REI 12h, Group 4). See rates based on row spacing on label. Systemic seed treatment. For early season control. thiamethoxam (Platinum): 5 to 8 oz/A (30 dh, REI 12h, Group 4). Systemic insecticide applied to seed pieces in-furrow during planting, impregnated on dry granular fertilizer, or as directed spray at plant emergence or during last hilling operation. Must incorporate into root zone with sufficient irrigation within 24 hours. DO NOT apply as a foliar spray. zeta-cypermethrin (Mustang*): 3.4 to 4.3 oz/A (1 dh, REI 12h, Group 3A). WirewormsTo avoid wireworm problems, potatoes should not be grown in rotation with sod or grass crops. Delay planting susceptible crops, such as potatoes or corn, on such land for at least two years after the sod has been broken. If wireworms are present, broadcast insecticide and incorporate into soil, preferably when soil temperature is above 60°F, or use furrow application. thiamethoxam (Platinum): 5 to 8 oz/A (30 dh, REI 12h, Group 4). Systemic insecticide applied to seed pieces in-furrow during planting, impregnated on dry granular fertilizer, or as directed spray at plant emergence or during last hilling operation. Must incorporate into root zone with sufficient irrigation within 24 hours. DO NOT apply as a foliar spray. For seedpiece protection only. Disease ControlVirus control will be enhanced by buying certified seed. Consult seed producers to determine what the certification covers. Destroy cull piles and volunteer plants. Do not keep potatoes for seed. NOTE: For the products for disease control listed below, one product trade name and formulation is provided for each active ingredient (common name) as an example of rates, days to harvest (dh), REI, and special instructions. In many cases there are other products available with the same active ingredient. Please see Table 22 and Alphabetical Listing by Trade Name for more information on products with the same active ingredients. Seed Piece Treatment (Fungi)Potato seed treatment is one of the more overlooked portions of a whole-season disease control program. Properly suberized and properly treated seed will provide a better, more uniform stand of plants. Proper application of the appropriate material is necessary. Too much chemical may prove phytotoxic. Inadequate coverage may not totally protect the seed-piece. Dust formulations are preferable for cut seed. CAUTION: Dip treatments may spread bacteria to seed pieces which were previously not affected. NOTE: Many of these seed treatments are now formulated with Douglas fir or alder bark as a carrier. Improved healing of the cut surface has been reported with these products. Some seed treatments can be purchased combined with imidacloprid. Do not use treated seed piotatoes for feed or food purposes. Bacillus subtilis GB03 (Companion Liquid Biological Fungicide): 1.0-2.0 fl oz/gal. fludioxonil (Maxim Potato seedpiece protectant): 0.5 lb/100 lb seed-pieces. (REI 12h, Group 12). Apply to cover thoroughly. Trichoderma harzianum Rifai strain KRL-AG2 (RootShield WP): 0.3-3.0 oz/100 lb seed. Early Blight (Alternaria solani)Crop losses can be heavy if serious defoliation occurs before or soon after flowering. Apply any of the following fungicides when plants are 4” to 6” tall. Begin applications earlier if late blight is found in your area, or if disease forecast systems recommend beginning a protection program. Repeat at five- to seven-day intervals, depending on amount of moist weather or dew. Use shorter interval under cool (60°F to 70°F) moist conditions. Incorporate diseased vines after harvest and avoid growing pepper, tomato, and potato in a continuous rotation. Allow tubers to mature fully before harvesting, avoid harvesting when the soil is wet, and prevent mechanical injury during harvest and handling. Proper fertilization and mineral balance will reduce susceptibility of plants to early blight. boscalid (Endura): 2.5-4.5 oz/A (10 dh, REI 12h, Group 7). Begin applications prior to disease onset and continue on 7-14 day intervals. chlorothalonil (Bravo Ultrex): 0.7 lb/A before vines close between rows; 0.9-1.36 lb/A after vines close between rows or when disease severity values are reached (7 dh, REI 12h, Group M5). Apply lower rates at seven to 10 day intervals and apply at five to seven day intervals when plants are growing rapidly or disease conditions are severe. pyraclostrobin (Headline): 6-9 fl oz/A. (3 dh, REI12h, Group 11). Do not make more than one application of Headline before alternating with a fungicide with a different mode of action. Do not alternate with Quadris. pyrimethanil (SCALA SC Fungicide): 7 fl oz/A. ( 7 dh, REI 12h, Group 9). Use only in a tank mix with another effective early blight fungicide. Late Blight (Phytophthora infestans)Late blight can occur from infected seed potatoes, or infected potato debris overwintered in the field. New late blight strains introduced into the region are resistant to metalaxyl. Do not leave cull pules of potatoes in the field. The fungicides used for early blight have some protective ability against Phytophthora but cannot be relied on to provide significant control. If late blight is reported within one half mile, begin applications of an appropriate fungicide . Plants with significant disease should be plowed under. Check with your local extension specialist for the availability of special exemption fungicides. cyazfamid (Ranman): 1.4-2.75 fl oz/A. (7 dh, REI 12h, Group 21). Do not make more than one application before alternating with a fungicide with a different mode of action. Addition of an organosilicone surfactant may be desirable. mandipropamid plus difenconazole (Revus Top): 5.5-7.0 fl oz/A. (14 dh, REI 12h, Groups 40 & 3). Addition of a spreading/penetrating type of adjuvant is recommended. Make no more than two consecutive applications before alternating with another fungicide with a different mode of action. mancozeb plus zoxamide (Gavel 75DF): 1.5-2.0 lb/A. (3 dh, REI 48h, Group M3 plus 22). Increase the use rate according to vine development. Use maximum labeled rate at row fill. Common Scab (Streptomyces)Scab is caused by the soilborne bacterium Streptomyces scabies. The disease tends to be prevalent when soil is dry during tuber initiation, soil pH is above 5.2, and non-decomposed manure is used as fertilizer. Continuous cropping of potato will also increase the disease. When planting susceptible varieties, avoid fields with a history of scab. When scab is present, rotate out of potatoes for at least two years. Beets, carrots, radish and some weeds can also be hosts. Maintain soil at 5.0 to 5.2. Mancozeb may be useful in controlling seed-borne scab. The varieties Norchip, Norland, Pike, Salem and Superior are resistant to scab. Allengany, Andover, Atlantic, Chieftain, Elba, Genesee, Monoma, Reba and Redsen are moderately resistant. Katahdin, Kennebec and Snowden are moderately susceptible. Chippewa, Kanona, Norwis and Yukon Gold are very susceptible. Pythium LeakLeak can be a problem in stored potatoes, especially bruised, immature potatoes harvested in hot weather. Verticillium and Fusarium WiltVerticillium and Fusarium are soil-borne fungi that cause vascular wilts of potato. They can be introduced into fields by contaminated seed or soil. Continual potato production tends to result in an increase in wilt disease. A combination of lesion nematodes and Verticillium results in early dying. Rotation with nonsusceptible crops such as grasses will reduce disease. Destruction of infected potato vines by tillage encourages rapid decomposition and lessens the build-up of soil inoculum. At this time, there are no varieties resistant to Fusarium Wilt. Avoid highly susceptible cultivars and start with certified, disease-free seed pieces. Potato Leaf Roll Virus (PLRV)Potato Leaf Roll Virus is the most serious virus disease of potatoes in New England and can result in significant yield reductions. The virus is transmitted by aphids in a persistent manner. The virus can overwinter in unharvested tubers which may develop into virus-infected volunteer plants. Plant virus-free, certified seed. Remove volunteer plants. Rogue plants with virus symptoms. When populations of aphids reach economic thresholds, treatment is warranted. Do not use any of last year’s potato harvest for seed. Potato Virus S (PVS), Potato Virus A (PVA), Potato Virus X (PVX), Potato Virus Y (PVY Rugose Mosaic)These viruses may occur singly or in combination. PVY, PVS and PVA are spread by aphids in a nonpersistent manner. PVX is not known to be spread by aphids but is easily spread by plant-to-plant contact, farm machinery or cultural practices. Plant virus-free certified seed. Plant early, use resistant varieties, and control aphid populations. |
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To purchase copies of the Guide and Photo Supplement, contact your state Extension publication office, or the University of Massachusetts Extension Bookstore at 1-877-UMASSXT (within Massachusetts) or 413-545-2717.