Annual and Perennial Grass Weeds

clethodim (Select2EC and other trade names)

Rate 0.09 to 0.25 lb ai/a (6 to 16 oz/a Select 2EC or Intensity); 0.07 to 0.24 lb ai/a (9 to 32 fl oz/a Select Max or Intensity One)

Time Apply to actively growing grasses at labeled stage of growth.

Remarks Controls grass only. Refer to label for specific herbicide rates, weed species, and weed size. Use crop oil concentrate at 1 gal/100 gal spray mix. Most effective on actively growing grasses. Larger, more mature grasses often can be controlled but may require two applications. Use the higher rates for perennial grass control.

Caution Do not exceed 0.5 lb/a (32 oz/a of Select 2EC or 64 fl oz/a of Select Max) per season. When using Select 2EC, do not add nitrogen fertilizer-source spray-adjuvants to the spray mixture. Preharvest interval is 21 days. For repeat applications, wait at least 14 days between applications.

Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor

Chemical family Cyclohexanedione

glyphosate (many trade names)

Rate 1% to 2% solution

Time Apply to actively growing weeds.

Remarks Not all glyphosate formulations have mint on the label. Rate and timing depend on target weeds. Apply as a spot treatment only, to no more than 10% of any acre. Can reapply in the same area at 30-day intervals.

Caution The sprayed crop will be killed. Avoid any drift outside of spayed area, otherwise those plants could be killed or injured. Preharvest interval is 7 days.

Site of action Group 9: inhibits EPSP synthase

Chemical family None generally accepted

glyphosate (many trade names)

Rate 33% solution (1 gal Roundup Ultra in 2 gal water) in rope or sponge-wick applicators, or a 33% to 100% glyphosate solution in porous-plastic applicators

Time Apply to actively growing weeds that are at least 6 inches taller than the mint.

Remarks Not all glyphosate formulations are labeled for this use. Wiper applicator contact point with the weed foliage should be at least 2 inches above the crop. Weeds should be at least 6 inches taller than the crop. Results may be better with two applications made in opposite directions. Operate at no more than 5 mph. Do not apply to wet weeds.

Caution Contact with the herbicide solution, whether by applicator drips or inadvertent wiping of the mint, will damage or kill the mint plants contacted. Preharvest interval is 7 days. Sequential application may be made to the same area at 30-day intervals.

Site of action Group 9: inhibits EPSP synthase

Chemical family None generally accepted

quizalofop (Assure II and other trade names)

Rate 0.034 to 0.0825 lb ai/a (5 to 12 oz/a product)

Time Apply to actively growing annual or perennial grasses at appropriate stage of grass growth as indicated on the label.

Remarks Controls grass only. Refer to label for specific herbicide rates, weed species, and weed size. Always add a crop oil concentrate at 1% v/v gal spray mix. Most effective on actively growing grasses; larger, more mature grasses can often be controlled but two applications may be required. Will not control annual bluegrass or any of the fine fescues.

Caution Preharvest interval is 30 days. Do not exceed two applications per season (0.165 lb ai/a). Tank-mixes with postemergence broadleaf herbicides have reduced control of most grass species. Application interval must be seven days or greater. Do not apply if rain is expected within 1 hour after application. Consult label for crop rotation restrictions.

Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor

Chemical family Aryloxyphenoxy propionate

sethoxydim (Poast,Rezult G)

Rate 0.28 to 0.47 lb ai/a (1.5 to 2.5 pints/a, maximum 5 pints/a per year)

Time Apply to actively growing annual or perennial grasses at growth stage indicated on label.

Remarks For grass control only. Refer to label for specific herbicide rates, weed species, and weed sizes. Always add a nonphytotoxic crop oil concentrate to the spray tank at 2 pints/a or Dash HC at 1 pint/a. Sethoxydim is most effective on actively growing grasses before they have been cut and before they reach the maximum size indicated on the label. Larger, more mature grasses can often be controlled, but two applications may be required. Sethoxydim will not control annual bluegrass or any of the fine fescues and is weak on downy brome and quackgrass.

Caution Control may be erratic on grass stressed by drought, temperature extremes, insect damage, herbicide injury, or other factors. Do not apply if rain is expected within 1 hour after applying. Preharvest interval is 20 days. Do not graze treated fields or use spent hay or straw as livestock feed. Do not exceed two applications or 5 pints/a a season. Do not tank-mix except with herbicides listed on the Poast label.

Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor

Chemical family Cyclohexanedione