Clover Seed
 Andrew Hulting
Revised November 1, 2008

CLOVERS—Red, White, Ladino, Crimson, and Arrowleaf
•   paraquat (Firestorm)
Idaho only
Rate  0.64 to 1.0 lb ai/A (1.7 to 2.7 pints/A Firestorm)
Time  For preharvest foliage desiccation, when clover seeds are mature.  Do not harvest clover seed until at least 4 days after application.
Remarks  Seed crops only. Do not make more than 2 applications per year.
Caution  A restricted-use pesticide.  Do not graze or feed treated forage and screenings to livestock. Do not use seed from treated plants for food, feed, or oil.  All processed clover seed must be tagged "not for human consumption" and the grower is responsible for informing the processing facility that the clover was treated with paraquat.  Do not apply Firestorm through any type of irrigation equipment.
Site of action  Group 22: photosystem I electron diversion
Chemical family  Bipyridilium
•   diquat (Reglone Desiccant)
Rate  0.37 to 0.5 lb ai/A (1.5 to 2 pints/A Reglone)
Time  For preharvest foliage desiccation, when clover seeds are mature.
Remarks  Seed crops only. Desiccation is complete in 3 to 10 days.
Caution  Do not graze or feed treated forage to livestock. Do not use seed from treated plants for food, feed, or oil.
Site of action  Group 22: photosystem I electron diversion
Chemical family  Bipyridilium
•   pronamide (Kerb 50W)
Rate  0.5 to 2 lb ai/A (1 to 4 lb/A Kerb 50-W)
Time  Apply after clover reaches the trifoliolate leaf stage. Results are best when applied under cool conditions (55°F or cooler) with rain following. Apply before soil freezes and to fields where crop residues have been removed or evenly dispersed
Remarks  Controls annual grasses and volunteer cereals in new or established stands. Use higher rate for well-established grasses or volunteer grains. Does not control groundsel, hawksbeard, mayweed, and other members of the Asteraceae family.
Caution  A restricted-use pesticide. Do not graze treated field or harvest for forage for 120 days after treatment. Do not plant field to cereals or to a grass crop immediately following clovers that were winter killed. See Kerb 50-W label for crop rotation restrictions.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Benzamide
•  EPTC (Eptam 7E or Eptam 20G)
Rate  2 to 4 lb ai/A (2.25 to 4.5 pints/A Eptam 7-E or 15-20 lbs/A Eptam 20-G) 
Time  Apply to a clean, residue-free seedbed before final disking and harrowing. Incorporate into the top 2 to 3 inches of soil immediately to prevent losing the herbicide. Whenever possible, apply and incorporate in the same operation.  Incorporation in two directions is recommended for heavy soils and perennial grass weed control. Clovers may be seeded any time after EPTC is incorporated into the soil.
Remarks  Controls annual and perennial grasses (e.g., quackgrass and creeping velvetgrass) and certain broadleaf weeds.
Caution  Temporary crop stunting and sealing of the first leaves will occur if germination conditions are not optimum. Do not use if a grass or small-grain nurse crop is to be planted with the clover. Do not use on white Dutch clover.
Site of action  Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family  Thiocarbamate
•  benefin (Balan DF)
Rate  1.2 to 1.5 lb ai/A (2 to 2.5 lb/A Balan DF)
Time  Before planting clover, benefin must be incorporated into the top 2 to 3 inches of the seedbed.
Remarks  Controls annual grasses and certain annual broadleaf weeds. Application rates are based on soil texture. Use the 2.5 lb/A rate on  fine clay soils and the lower 2 lb/A rate on coarse sandy soils.
Caution  Weed control may vary if incorporation is delayed more than 4 hours after application. Do not apply benefin to soils that are subject to prolonged flooding; poor weed control may result. In arid, irrigated areas, do not rotate to a small grain or other grass crop for 10 mo to avoid crop injury due to herbicide carryover. See label for additional crop rotation restrictions.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  sethoxydim ( several trade names)
Rate  0.19 to 0.47 lb ai/A 
Time  Apply to actively growing annual or perennial grasses at growth stage listed on labels.
Remarks  For grass control only. Most effective on actively growing grasses. See labels for specific rates, weed species, and weed size. Will not control annual bluegrass or fine fescues and is weak on downy brome and quackgrass. Always add a crop oil concentrate at 2 pints/A.
Caution  Control may be erratic on grasses stressed by drought, temperature extremes, insect damage, herbicide injury, or other factors. Do not apply if rain is expected within 1 hour after application. Do not exceed 1.2 lb ai/A per season. See individual labels for livestock grazing and feeding restrictions or cutting for forage or hay restrictions.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  clethodim (several trade names)
Rate  0.094 to 0.25 lb ai/A 
Time  Apply to actively growing annual or perennial grasses at the appropriate stage of grass growth as indicated on labels.
Remarks  For grass control only. See label for specific rates, weed species, and weed size. Always add a crop oil concentrate at 1% v/v in the finished spray volume. Control may be erratic on grasses stressed by conditions such as drought, temperature extremes, and insect and herbicide damage. Do not apply if rain is expected within 1 hour of application. 
Caution  Do not exceed 0.25 lb ai/A of  clethodim per season. Adding fertilizer to spray solution is not recommended. Preharvest interval is 15 days. Do not use on clover when soil pH is 5.5 or less. See individual labels for livestock grazing and feeding restrictions or cutting for forage or hay restrictions. 
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  fluazifop-P butyl (Fusilade DX)
Idaho only
Rate  Up to 0.31 lb ai/A (up to 20 fl oz/A Fusilade DX)
Time  Make first application (12 fl oz/A) when quackgrass is 6 to 10 inches high. A second application may be made (8 fl oz/A) 2 to 3 wk after the first but before quackgrass exceeds 10 inches high.
Remarks  For selective quackgrass control in clover grown for seed in Idaho, always add a crop oil concentrate at 1% v/v.
Caution  Do not feed or graze clover after applying. Do not cut treated clover for hay or forage. The seed producer must give a copy of the label to the seed conditioner. Processed seed must be labeled “not for human or animal consumption.” Refer to main label for crop rotation restrictions.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Aryloxyphenoxy propionate
•  bentazon (Basagran)
Oregon and Washington only
Rate  Up to 1 lb ai/A (up to 2 pints/A Basagran)
Time  Apply in spring to young, actively growing weeds in clover grown for seed in Washington and Oregon.
Remarks  Controls certain broadleaf weeds and sedges soon after emergence. For consistent control, add a nonphytotoxic crop oil concentrate. Some clover leaf burning may occur, but symptoms generally are outgrown within 10 days of treatment.
Caution  Thorough coverage necessary for adequate weed control. Do not apply to stressed clover. Do not graze livestock or harvest forage or hay for at least 36 days after treatment. Do not exceed 4 pints/A Basagran per year.
Site of action  Group 6: photosystem II inhibitor
Chemical family  Benzothiadiazole
•  imazamox (Raptor) +
•  bentazon (Basagran)
Rate  0.04 lb ai/A (5 fl oz/A Raptor) + 0.25 to 0.5 lb ai/A (8 to 16 fl oz/A Basagran)
Time  Apply when clover has at least two trifoliolate leaves and most weeds are 1 to 3 inches tall. Imazamox applications to clover grown for seed must be made before bloom.
Remarks  Applications of imazamox to clover grown for seed require adding surfactant, nitrogen fertilizer, and Basagran herbicide. Use a nonionic surfactant with at least 80% ai at 0.25% v/v (1 quart/100 gal spray solution). Apply to red, white, and crimson clover only.
Caution  More than 16 fl oz/A of Basagran may reduce grass control. When using Raptor plus Basagran, always follow the more restrictive label. Do not apply Raptor more than once per growing season. Imazamox use on crimson, red, or white clover may cause crop injury or loss when applied at the 5oz/A rate to stressed clover. See additional use cautions on Raptor label.
Site of action  (imazamox) Group 2: acetolactate synthase (ALS) inhibitor; (bentazon) Group 6: photosystem II inhibitor
Chemical family  (imazamox) Imidazolinone; (bentazon) Benzothiadiazole 
•  imazethapyr (Pursuit) 
Rate  0.05 to 0.094 lb ai/A  (3 to 6 fl oz/A Pursuit)
Time  Apply to seedling clover that has at least two to three trifoliolate leaves and when most weeds are 1 to 3 inches tall.  Imazethapyr may be applied to established clover in the fall and in spring to dormant or semidormant clover less than 3 inches tall. Imazethapyr applications to clover grown for seed must be before bloom.
Remarks  Applications of imazethapyr to clover grown for seed require adding surfactant and nitrogen fertilizer. Use a nonionic surfactant with at least 80% ai at 0.25% v/v (1 quart/100 gal spray solution). 
Caution  Do not feed, graze, or harvest clover within 30 days of applying imazethapyr.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Imidazolinone
•  pendimethalin (several trade names)
Oregon and Idaho only
Rate  0.95 to 3.8 lb ai/A 
Time  Apply to established clover before weeds emerge and before clover is more than 6 inches high. Herbicide is most effective when incorporated into the weed germination zone by rain or irrigation within 7 days of application.
Remarks  Special local needs labels ID-000007 and OR-020003 (for Prowl 3.3EC), ID-060007 and OR-060006 (for Prowl H2O) and ID‑060017 and OR-070025 (for Stealth). Controls dodder, most annual grasses, and certain broadleaf weeds as they germinate, but will not control established weeds.
Caution  Do not apply to seedling clover. Do not feed or graze clover after applying. Do not cut treated clover for hay or forage. Do not use harvested seed for sprouting. The seed producer must give a copy of the label to the seed conditioner. Processed seed must be labeled “not for human or animal consumption.” Refer to main labels for crop rotation restrictions.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  MCPA amine (several trade names)
Rate  See individual product labels for appropriate rate, but generally 0.23 to 0.46 lb ai/A .
Time  Apply in late fall or early spring when red clover is dormant, before active growth starts.
Remarks  To control broadleaf weeds in established stands of red clover only.
Caution  Older, established clover stands may show stem twisting injury after application, which may retard growth.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  paraquat (several trade names)
Rate  0.26 to 0.78 lb ai/A 
Time  Apply to fall-planted, newly established or well-established stands between November 15 and January 15, when crop is dormant and before spring growth starts.
Remarks  To control winter annual grasses and broadleaf weeds in  red and white clover. Add 1 to 2 pints of a nonionic surfactant or 1 gal crop oil concentrate per 100 gal water. For dense stands of grass, paraquat plus pronamide gives better control than paraquat alone. Foliage on crop at time of application will be burned.
Caution  A restricted-use pesticide. Do not graze or harvest treated forage for 60 days after applying. Do not apply more than once per season. When applying to fall-planted red clover in the first winter or to red clover planted with a nurse crop the previous spring use the lowest labeled rate.  Do not apply if regrowth after grazing or cutting is larger than 2 inches tall.
Site of action  Group 22: photosystem I electron diversion
Chemical family  Bipyridilium
•  pelargonic acid (Scythe)
Rate  Apply a 3% to 10% solution (v/v) in a 75 to 200 gal/A spray solution.
Time  Apply when clover is dormant to control actively growing weeds.  All partially green plant growth will be killed or stunted, but activity may be limited with cool weather after application.
Remarks  Use higher rates to control perennial weed species or when maximum vegetative burndown is desired.  Adequate spray coverage is essential to maximize activity.  Scythe is not translocated throughout plants, and is a nonselective contact material.
Caution  Do not apply Scythe through any type of irrigation equipment.  There are no grazing or feeding restrictions or plant back restrictions associated with Scythe applications.
Site of action  Group 26: unknown
Chemical family  Carboxylic acid
•  diuron (several trade names)
western Oregon only
Rate  1.6 lb ai/A 
Time  Apply when red clover is dormant, from October 15 to December 15.
Remarks  Controls annual weeds such as bluegrass, chickweed, hawksbeard, rattail fescue, ryegrass, and velvetgrass.
Caution  Apply to red clover only. Stands should be established at least 9 mo and in vigorous condition. Do not replant to any crop within 1 yr after application to limit potential for rotational crop injury.
Site of action  Group 7: photosystem II inhibitor
Chemical family  Substituted urea
•  oxyfluorfen (Goal 2XL) 
Oregon only
Rate  0.03 to 0.09 lb ai/A (2 to 6 fl oz/A Goal 2XL) 
Time  Apply to established dormant clover from December 1 to February 15.
Remarks  Controls broadleaf weeds including common mallow, groundsel, filaree, henbit, and speedwell. 
Caution  Apply to red and white clover for seed only. Apply preemergence or up to six-leaf stage of weeds. Do not feed or graze clover after applying. Do not cut treated clover for hay or forage. Do not use harvested seed for sprouting. Processed seed must be labeled “not for human or animal consumption.” Do not rotate to a small grain crop for 10 mo, to avoid crop injury due to herbicide carryover. See label for additional crop rotation restrictions.
Site of action  Group 14: protoporphyrinogen oxidase inhibitor
Chemical family  Diphenylether