carfentrazone-ethyl (Aim EC or several trade names, 2 lb ai/gal)
Rate for the preplant timing application Up to 0.031 lb ai/A (2 fl oz/A carfentrazone-ethyl)
Application methods Ground application in a minimum of 10 gal/A or aerial in a minimum of 3 gal/A. Use higher spray volumes when there is a dense weed population or crop canopy. Apply carfentrazone-ethyl with a crop oil concentrate (COC) at 1% v/v or a methylated seed oil (MSO) at a minimum of 1 quart/A or 1% v/v when applied in volumes of more than 20 gal/A.
Remarks Apply to actively growing weeds not more than 4 inches tall or rosettes 3 inches in diameter. Coverage is essential for good control. Tank-mixes with other herbicides may increase spectrum of control. Carfentrazone-ethyl is also formulated as a 40% WDG. Calculate rates with this product accordingly.
Caution Do not exceed 0.031 lb ai/A (2 fl oz carfentrazone-ethyl) for preplant (and/or preemergence) burndown treatments. Do not exceed 0.181 lb ai/A (11.6 fl oz carfentrazone-ethyl) total per crop season. This total allowable usage applies to all applications made to the field per calendar year including burndown treatments and harvest-aide.
Tank-mixtures Tank-mixes with other herbicides labeled for preplant burndown applications in potato, such as glyphosate or paraquat, may increase spectrum of control. Read and follow applicable "Restrictions and Limitations and Directions for Use" on all product labels in a tank-mixture. The most restrictive labeling applies to use of tank-mixtures.
Re-cropping restrictions Following an application of carfentrazone-ethyl, a registered crop may be planted at any time.
Rotational cropping restrictions A field may be rotated to a registered crop at any time after an application. All other crops may be planted after 12 months.
Site of action Group 14: protoporphyrinogen oxidase (Protox) inhibitor
Chemical family Triazolinone
EPTC (Eptam 7E)
Soil active, only
Rate for the preplant and preplant impregnated on dry bulk fertilizer application timing 3.5 to 9 pints/A (3 to 7.9 lb ai/A). For quackgrass control, preplant: 4.5 pints/A (4 lb ai/A). For hairy nightshade, preplant: use a minimum of 5 pints/A (4.4 lb ai/A)
Application methods Soil surface must be free of dew and incidental moisture, and dry to at least 0.5 inch deep. EPTC is highly volatile. Incorporate into soil to prevent losing the herbicide. Any cultivation after application should be shallow (this means half the depth that the herbicide was incorporated). Whenever possible, apply and incorporate in the same operation. If application and incorporation are separate, Eptam must be incorporated the same day as it is applied. Preplant: apply and incorporate just before planting.
Incorporation methods Preplant: incorporate 2 to 3 inches deep with power-driven cultivation equipment, or set tandem disks, field cultivators, or rotary-driven or spring-toothed cultivators to cut 4 to 6 inches deep. See label for equipment-specific recommendations. If potatoes are to be hilled after applying, be sure to mix herbicide 3 inches deep or more.
For semiarid areas of eastern Washington, eastern Oregon, and Idaho only: 1) if EPTC is applied preplant and incorporated separately, incorporate the same day as application; 2) apply and incorporate dry bulk fertilizer impregnated with EPTC on the same day; 3) sprinkler-incorporate EPTC immediately after ground application with 0.5 to 0.75 inch water.
Application and incorporation must be within 5 days after the last tillage; results will be poor if weeds have germinated.
Remarks EPTC is not effective on emerged weeds.
Caution Do not exceed 14 pints/A (12.25 lb ai/A) per crop year. Preharvest interval is 30 days. Tillage after applying Eptam brings untreated soil to the surface; weed control may be reduced.
Tank-mixtures Read and follow applicable "Restrictions and Limitations and Directions for Use" on all product labels in a preplant tank-mixture. The most restrictive labeling applies to use of preplant tank-mixtures. Trifluralin can only be applied in a single preplant application when tank mixed with EPTC. See the registered labels for rates.
Re-cropping restrictions No re-cropping or rotational restrictions for EPTC on the label.
Site of action Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family Thiocarbamate
glyphosate (Glyphosate Original, Roundup PowerMAX, Roundup WeatherMAX, Roundup Custom, Roundup Original Max, or several trade names)
Foliar active, only
Rate for the preplant timing application 0.38 to 0.75 lb ae/A for volunteer grains. See labels for specific grains and rates.
Note: Apply when annual grain is less than 18 inches tall and before planting potatoes.
Application methods Ground or aerial: apply in 3 to 10 gal/A water by ground or 3 to 5 gal/A water by air. Some glyphosate formulations require using nonionic surfactant; see label for details on additive use. Adding 1 to 2% dry ammonium sulfate (AMS) by weight or 8.5 to 17 lb/100 gal spray mix may increase performance. Also may use the equivalent rate of AMS in a liquid formulation.
Remarks Good growing conditions enhance volunteer grain control with glyphosate.
Caution Glyphosate has no soil-residual activity and will not control weeds emerging after application. Follow all use restrictions and precautions on the label.
Tank-mixtures Tank mixtures are not stated/Approved on most glyphosate labels. Read and follow applicable "Restrictions and Limitations and Directions for Use" on all product labels in a tank-mixture. The most restrictive labeling applies to use of tank-mixtures.
Site of action Group 9: inhibits EPSP synthase
Chemical family None generally accepted
metolachlor (Me-Too-Lachlor, Stalwart, or several trade names, 8 lb ai/gal)
Soil active, only
Rate for the preplant timing application 1 to 2 pints/A (1 to 2 lb ai/A product). Use lower rate on coarse soils or soils low in organic matter (OM). Use higher rate on soils that are relatively fine or high in OM. Up to 2.75 pints/A can be used on soils with 6% to 20% OM.
Time If applied preplant: do not apply as a preemergence treatment.
Application methods Ground or aerial. Metolachlor may be applied impregnated on dry fertilizer.
Incorporation methods Preplant: incorporate into top 2 inches of soil using a finishing disk, harrow, rolling cultivator, or similar implement within 14 days of planting. Evenly distribute herbicide in top 2 inches of soil. Do not damage potato seed pieces or sprouts with incorporation equipment.
Remarks Effectiveness will be reduced if later cultivation exposes untreated soil. If conditions are cool and wet after application, Metolachlor may delay maturity and/or reduce yield of Superior and other early-maturing varieties.
Caution Do not use on muck or peat soils.
Tank-mixtures Read and follow applicable "Restrictions and Limitations and Directions for Use" on all product labels in these preplant tank-mixtures. The most restrictive labeling applies to use of tank-mixtures.
Re-cropping restrictions If a crop treated with metolachlor fails, any metolachlor-labeled crop may be planted immediately. Do not make a second broadcast application of metolachlor. If metolachlor was banded in the failed crop and the second crop is planted in the untreated row middles, a second banded treatment may be applied.
Rotational cropping restrictions Alfalfa may be planted after 4 months; barley, oats, rye, or wheat may be planted at 4.5 months; and tomato may be planted 6 months after metolachlor application. Clover may be planted 8 months after. Any metolachlor-labeled crop or root crops, tobacco, barley, buckwheat, milo (sorghum), oat, rye, wheat, cabbage, or peppers may be planted the spring after metolachlor applications the previous growing season. All other rotational crops may be planted 12 months after a layby application. Any metolachlor-labeled crop or tobacco, cabbage, or peppers may be planted the next spring after layby or multiple applications of metolachlor.
Site of action Group 15: inhibits very long chain fatty acid synthesis
Chemical family Chloroacetamide
metribuzin (TriCor DF 75% (product labeled for preplant timing))
Soil and foliar active. May be applied on dry bulk fertilizer in Idaho only
Rate for the preplant timing application 0.67 to 1.33 lb/A (0.5 to 1 lb ai/A Tricor DF 75%).
Note: Other metribuzin formulations may or may not have preplant-incorporated application timing on the label. Follow current label restrictions.
Time in Idaho Apply preplant-incorporated as a broadcast spray or impregnated on dry fertilizer.
Application methods Ground, aerial, or impregnated or coated on 500 to 1,200 lb/A dry bulk fertilizer.
Incorporation methods Preplant applications: incorporate evenly 4 to 6 inches deep by double-disking at right angles.
Remarks Metribuzin may not control triazine-resistant weed populations. Refer to the metribuzin label for proper rate for soil type, dry bulk fertilizer application information and all other recommendations, cautions, or special precautions that must be followed.
Caution Short-season, white-skinned varieties can be susceptible/moderately susceptible to metribuzin and may be injured. Other new varieties may be sensitive to metribuzin. When growing varieties for the first time, do not treat entire acreage until potato sensitivity is determined.
Tank-mixtures Read and follow applicable "Restrictions and Limitations and Directions for Use" on all product labels in preplant tank-mixtures. The most restrictive labeling applies to use of tank-mixtures.
Re-cropping restrictions None on label.
Rotational cropping restrictions Do not plant onions, lettuce, cole crops, or cucurbits during the growing season following metribuzin applications. Do not plant sugar beets for 18 months after metribuzin application. Certain cereal varieties are sensitive to metribuzin (see cereal section of label) and should not be planted during the growing season after metribuzin use, unless moldboard plowing deeply enough to mix the upper 8 inches of soil and potato vines left in rows after harvest are uniformly distributed over the soil surface before plowing.
Site of action Group 5: photosystem II inhibitor
Chemical family Triazinone
paraquat (Gramoxone SL or Inteon, 2 lb paraquat cation/gal; Firestorm, 3 lb paraquat cation/gal; or several trade names depending upon the formulation)
Foliar active, only
Rate for the preplant timing application 1 to 2 pints/A (0.25 to 0.5 lb ae/A) Gramoxone SL or Inteon; or 0.7 to 1.3 pints/A (0.26 to 0.5 lb ae/A Firestorm) for preplant control of other volunteer grains, weeds, or grass cover crops. For volunteer barley control in Idaho, Oregon, and Washington only: use 0.5 to 1 pint/A (0.125 to 0.25 lb ae/A) Gramoxone SL or Inteon; 0.4 to 0.7 pints/A (0.15 to 0.26 lb ae/A) Firestorm to preformed beds before planting potatoes. Do not exceed three applications of Firestorm per year. There are other trade names for these paraquat formulations.
Time Apply before planting potatoes. Grass or volunteer cereal grain control is best if applied before tillering or after boot stage.
Application methods Ground or aerial. Add nonionic surfactant with 75% or more surface-active agent at 0.125% v/v (1 pint/100 gal spray mix), or crop oil concentrate at 1% v/v (1 gal/100 gal spray mix) for ground applications, or 1 pint/A for aerial applications.
Remarks Nonselective, postemergence herbicide. Kills most green plant growth on contact, so good spray coverage is essential. Rainfast 30 minutes after application. Paraquat has no residual soil activity on crops planted later or weeds germinating later.
Caution Restricted use pesticide due to acute toxicity. For retail sale to and use only by certified applicators - not to be used by uncertified persons working under the supervision of a certified applicator. Follow all restrictions and precautions on label. Requires special safety equipment for handling, mixing, and spraying.
Tank-mixtures Must be applied alone for volunteer barley control, otherwise, see label for other allowable preplant tank-mix combinations.
Site of action Group 22: photosystem I electron diversion
Chemical family Bipyridilium
S-metolachlor (Dual Magnum, or several trade names, 7.62 lb ai/gal)
Rate for the preplant timing application 0.95 to 1.9 lb ai/A (1 to 2 pints/A), using lower rates on soils that are coarse or low in organic matter. Note: S-metolachlor also is formulated as Dual II Magnum or several trade names (7.64 lb ai/gal and includes a safener for corn) and as Dual IIG Magnum (16% G). Refer to the labels for those formulations to determine rates, timing, etc. for use in potatoes.
Time Apply preplant-incorporated or preplant-incorporated impregnated on dry bulk fertilizer.
Application methods Ground or aerial.
Incorporation methods Preplant-incorporated: incorporate before planting using a finishing disk, harrow, rolling cultivator, or similar implement that can uniformly incorporate herbicide into top 3 inches of soil.
Remarks During planting and later cultural practices, avoid bringing untreated soil to the surface.
Caution Do not apply preemergence after preplant incorporated application. Do not use on muck or peat soils. Crop may be injured after S-metolachlor if soil moisture is abnormally high during early crop development.
Tank-mixtures Read and follow the applicable "Restrictions and Limitations and Directions for Use" on all product labels in preplant tank-mixtures. The most restrictive labeling applies to use of tank-mixtures.
Re-cropping restrictions If the potato crop fails, corn, soybeans, potatoes, safflower, or other S-metolachlor-registered crops may be replanted immediately. Do not make a second broadcast application.
Rotational cropping restrictions Do not plant barley, oats, rye, or wheat until 4.5 months after application. Alfalfa may be planted 4 months after application. Clover may be seeded 9 months after application. Any crop labeled for S-metolachlor use and pod and root crops, buckwheat, or milo (sorghum) may be planted the spring after treatment.
Site of action Group 15: inhibits very long chain fatty acid synthesis
Chemical family Chloroacetamide
S-metolachlor + glyphosate (Sequence or several trade names, a formulated premix of 3 lb ai S-metolachlor + 2.25 lb ae/gal glyphosate)
S-metolachlor in this pre-mix only has soil activity; glyphosate in this pre-mix only has foliar activity
Rate for the preplant timing application Do not exceed 2.5 pints/A formulated product on coarse soils, 3.75 pints/A formulated product on medium soils with less than 3% organic matter, or 4 pints/A formulated product on fine textured soils with greater than 3% organic matter. Do not exceed 4 pints/A formulated product per season.
Time Apply before potatoes have been planted. This pre-mix may be applied up to 30 days before planting.
Application methods Ground in 15 to 40 gal/A or aerial in 3 to 15 gal/A water. Do not apply this product through any type of irrigation system. When foliage is dense, spray volume should be increased to ensure coverage of the target weeds. Flat-fan nozzles will result in the most effective application. Control of emerged weeds may be improved by adding dry ammonium sulfate at 8.5 to 17 pounds/100 gallons of water. Liquid formulations of AMS may be used at an equivalent rate.
Remarks This pre-mix is considered a foliar systemic herbicide which may be applied to control a broad spectrum of emerged weeds and can provide some residual control of certain weeds listed on the label. If rainfall or irrigation is not received within 7 days after application of Sequence, residual weed control may be reduced. Under these conditions, cultivate or use other weed control measures if weeds develop. If emerged at application time, weeds must be actively growing. For best possible annual weed control, apply to weeds 6 inches or less in height. If annual weeds have been mowed or grazed prior to application, wait for 3 to 4 inches of new growth to appear prior to application. When perennial weeds have been mowed or grazed, refer to the label for the recommended stage that new growth should reach prior to application.
Caution Do not harvest within 60 days after application.
Tank-mixtures This pre-mix can be tank mixed with metribuzin or pendimethalin (Prowl H2O/3.3EC or several trade names) for control or suppression of annual and perennial weeds, provided that the tank-mix product label allows use of the product. Refer to the labels for weeds controlled and application rates for these tank-mixtures.
Re-cropping restrictions If crop treated with this pre-mix alone is lost, corn, legume vegetables (succulent or dried), potatoes, sorghum, soybeans, sunflowers, or transplanted tomatoes may be replanted immediately.
Rotational cropping restrictions Do not plant barley, oats, rye, or wheat before 4.5 months after application; alfalfa 4 months; tomato 6 months; or clover 9 months. Buckwheat, milo (sorghum) cabbage, stone fruits, or tree nuts may also be planted in the spring following treatment.
Site of action Group 15: inhibits very long chain fatty acid synthesis; Group 9: inhibits EPSP synthase
Chemical family Chloroacetamide; none generally accepted
trifluralin (Treflan HFP or several trade names, 4 lb ai/gal)
Split application Preplant + postemergence may be made only in Idaho, Oregon and Washington and on soils with less than 2% OM: 0.75 pint/A (0.375 lb ai/A) before planting + 0.75 pint/A postemergence (0.375 lb ai/A), when potato plants have fully emerged. Incorporate the preplant application immediately. Refer to the Trifluralin + EPTC preplant section and in this Handbook and the labels for information on incorporation methods, remarks, cautions, and rotation crop restrictions.
trifluralin (Treflan HFP or several trade names, 4 lb ai/gal) + EPTC (Eptam 7E or several trade names, 7 lb ai/gal)
Trifluralin can be applied in a single preplant application only if tank mixed with EPTC and in Idaho, Oregon, Washington, only
Rate for the preplant timing application Trifluralin 0.75 pint/A (0.375 lb ai/A) + EPTC 3.5 to 9 pints/A (3 to 7.9 lb ai/A); use at least 4.5 pints/A EPTC for quackgrass control. For control of nightshade a minimum of 5 pints/A is recommended.
Time Single preplant application: only when tank mixed with Eptam.
Application methods Ground.
Incorporation methods Mechanically incorporate thoroughly into 2 to 3 inches of soil as soon as possible but no later than 24 hours after application.
Remarks Existing weeds must be destroyed by tillage before applying this herbicide tank mixture because trifluralin and EPTC do not control established weeds. Weed control may be erratic if cultivation exposes untreated soil between rows.
Caution Strictly adhere to label rates and precautions to prevent crop injury. If cultivation is required after application, avoid completely covering potato plants with treated soil. If treated soil is concentrated over the potato row/hill, emergence may be slowed and stems can become brittle. Do not apply to wet soils; weed control may be poor.
Tank-mixtures Preplant single application: only tank mixed with Eptam. Read and follow applicable "Restrictions and Limitations and Directions for Use" on the trifluralin and EPTC product labels in this preplant tank-mixture. The most restrictive labeling applies to use of tank-mixtures..
Rotational cropping restrictions In Idaho, Oregon, and Washington after a spring application of this preplant tank mixture, wait at least 12 months to plant sugar beets, red beets, spinach, corn, sorghum (milo), proso millet, oat, and annual or perennial grass crops or mixtures. Do not plant any of these crops for 18 months after application in fields that have not been irrigated, or that have been fallowed without irrigation or cultivation. Moldboard plowing 12 inches deep before planting these crops can reduce the possibility of crop injury. Do not plant vegetable crops, other than labeled for preplant application of this tank mixture, within 5 months after application.
Site of action Group 3: microtubule assembly inhibitor, Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family (trifluralin) Dinitroaniline; (EPTC) Thiocarbamate