EPTC (Eptam 7E or several trade names, 7 lb ai/A)
Soil active, only
Apply and incorporate just before planting potatoes for quackgrass control.
Rate 4.5 pints/A (4 lb ai/A)
Remarks Thoroughly till quackgrass before application; chop rhizomes into pieces 2 to 3 inches or smaller. EPTC must be incorporated immediately and thoroughly after application, either with a rotovator or by cross-disking. Use on mineral soils containing less than 10% organic matter. See previous entries in this section for application and incorporation methods, remarks, cautions, re-cropping and rotational cropping restrictions, and site of action and chemical family information for this herbicide.
Site of action Group 8: lipid synthesis inhibitor but not an ACCase inhibitor
Chemical family Thiocarbamate
rimsulfuron (Matrix SG; Matrix FNV; Solida; or several trade names, 25%)
Soil and foliar active
Rate 1 to 1.5 oz/A of the 25% DF (0.0156 to 0.023 lb ai/A) + nonionic surfactant (NIS) at 0.125 to 0.25% v/v (1 to 2 pints/100 gal spray solution) or crop oil concentrate or methylated seed oil (MSO) at 1% v/v (1 gal/100 gal spray solution)
Time Apply postemergence to 4- to 6-inch quackgrass.
Remarks Also may use as a split postemergence + postemergence application. Use 1 to 1.5 oz/A rimsulfuron + 0.125 to 0.25% nonionic surfactant (NIS) (1 to 2 pints/100 gal spray solution) at each application; do not exceed a total of 2.5 oz/A rimsulfuron. In split applications, make the second 14 to 28 days after the first. See previous entries in this section for application and incorporation methods, remarks, cautions, re-cropping and rotational cropping restrictions, and site of action and chemical family information for this herbicide. Applied postemergence, rimsulfuron may temporarily yellow potato foliage.
Under environmental stress (cool, wet or hot or humid weather), rimsulfuron applied postemergence also may stunt growth and cause leaf malformations. Potatoes recover within 7 to 15 days. To reduce injury, apply only if it has been sunny at least 3 successive days. Do not use on seed potatoes unless permitted by a supplemental label.
Site of action Group 2: acetolactate synthase (ALS) inhibitor
Chemical family Sulfonylurea
sethoxydim (Poast, 1.5 lb ai/gal or several trade names; Poast Plus or several trade names, 1 lb ai/gal)
Foliar active, only
Rate 2.5 pints/A the 1.5 lb ai/gal formulation or 3.75 pints/A of the 1.0 lb ai/gal formulation (0.47 lb ai/A)
Time Apply when quackgrass shoots are 6 to 8 inches tall. A second application at 0.28 lb ai/A (1.5 pints/A of the 1.5 lb ai/gal or 2.25 pints/A of the 1.0 lb ai/gal formulations) may be needed if quackgrass re-grows. Best results usually require repeated applications.
Remarks Always add a nonphytotoxic oil concentrate to spray tank at 2 pints/A. Add nitrogen to improve control. Cultivate 7 to 14 days after an initial or sequential application to aid control. May not eradicate quackgrass. Do not tank mix sethoxydim with other herbicides for control of quackgrass.
See previous entries in this section for application methods, remarks, cautions, re-cropping and rotational cropping restrictions, and site of action and chemical family information for this herbicide.
Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family Cyclohexanedione