Broadleaf Weeds and Canada Thistle

clopyralid (Stinger)

Rate 0.094 to 0.125 lb ae/a (0.25 to 0.33 pint/a Stinger)

Time Apply from 3-leaf up to early boot stage of winter wheat growth. Apply to actively growing weeds. Only weeds emerged at the time of application will be affected.

Remarks To control perennial weeds such as Canada thistle, use the 0.33 pint/a rate.

Caution Do not exceed 0.67 pint/a per crop year. Plant wheat, barley, oats, grasses, field corn, or sugar beets any time after treatment. See label for crop rotation restrictions on other crops. Do not apply by air.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

clopyralid + 2,4-D (Curtail)

Rate 0.095 to 0.126 lb ae clopyralid + 0.5 to 0.67 lb ae/a 2,4-D amine (2 to 2.66 pints/a Curtail)

Time Apply in spring to actively growing weeds, after winter wheat begins tillering up to jointing stage.

Remarks This combination is particularly effective on members of the sunflower family such as Canada thistle and mayweed. Controlling tough winter annual weeds such as corn gromwell and fiddleneck requires tank mixing with other herbicides. Check Curtail label for details on mixtures. For Canada thistle, apply after most basal leaves emerge but before bud stage.

Caution Do not plant wheat, barley, oats, grasses, or field corn within 30 days after applying Curtail. Do not plant sugar beets, including beets grown for seed, in the same growing season after applying Curtail. See label for crop rotation restrictions on other crops.

Site of action (both) Group 4: synthetic auxin

Chemical family (clopyralid) pyridine; (2,4-D) phenoxy acetic acid

clopyralid + MCPA (Curtail M)

Rate 0.092 to 0.122 lb ae/a clopyralid + 0.5 to 0.69 lb ae/a MCPA (1.75 to 2.33 pints/a Curtail M)

Time Apply in spring to actively growing weeds from the 3-leaf up to jointing stage of wheat growth. Only weeds emerged at the time of application will be affected.

Remarks For Canada thistle, apply after most basal leaves emerge but before bud stage.

Caution Do not plant wheat, barley, oats, grasses, or corn within 30 days after applying Curtail M. Do not plant sugar beets in the same growing season after Curtail M. See label for crop rotation restrictions on other crops.

Site of action (both) Group 4: synthetic auxin

Chemical family (clopyralid) pyridine; (MCPA) phenoxy acetic acid

clopyralid + MCPA + fluroxypyr (Weld)

Rate 0.063 to 0.094 lb ae/a clopyralid + 0.22 to 0.33 lb ae/a MCPA + 0.08 to 0.12 lb ae/a fluroxypyr (1.0 to 1.5 pints/a Weld)

Time Apply to winter wheat after 3-leaf stage through flag leaf emergence. Apply to weeds up to the 4-leaf stage or 4 inches high. Certain larger weeds may be controlled; see label for size recommendations and application timings.

Remarks Do not apply when crops are under moisture stress. Do not harvest treated wheat as forage or allow livestock to graze treated wheat within 7 days of application. Do not apply within 40 days of harvesting grain or straw. See Weld label for crop rotation restrictions in Oregon.

Site of action (all) Group 4: synthetic auxin

Chemical family (MCPA) phenoxy acetic acid; (fluroxypyr and clopyralid) pyridine

dicamba (several trade names) + MCPA (several trade names)

Oregon only

Rate 0.125 to 0.188 lb ae/a dicamba + 0.75 lb ae/a MCPA

Time Apply in spring when winter wheat has at least four tillers but before it begins to joint.

Remarks Controls many broadleaf weeds and kills or suppresses Canada thistle.

Site of action (both) Group 4: synthetic auxin

Chemical family (dicamba) benzoic acid; (MCPA) phenoxy acetic acid

fluroxypyr + clopyralid (several trade names)

Rate 0.094 to 0.125 lb ai/a fluroxypyr + 0.094 to 0.125 lb ai/a clopyralid

Time For best performance, apply to emerged and actively growing weeds 4 to 8 inches tall depending on rate. Apply to winter wheat from 3-leaf stage through flag leaf emergence.

Remarks Controls broadleaf weeds including kochia, wild buckwheat, Canada thistle, and prickly lettuce. Tank-mix compatible with MCPA, thifensulfuron or 2,4-D, and most grass herbicides.

Caution See label for rotation restrictions on other crops. Do not allow livestock to graze treated areas or harvest forage within 7 days of application. Preharvest interval for grain or straw is 40 days.

Site of action (both) Group 4: synthetic auxin

Chemical family (both) pyridine

tribenuron (several trade names)

Rate 0.008 to 0.016 lb ai/a

Time Apply after crop is in the 2-leaf stage but before the flag leaf is visible.

Remarks Results are best on young, actively growing weeds. For best performance, apply when temperatures are 60°F or higher and moisture is adequate before, during, and immediately after treatment. The 0.016 lb ai/a rate is effective on Canada thistle; apply at 4 to 12 inches of growth. Use with an 80% ai nonionic surfactant at 2 pints/100 gal.

Caution Replant wheat, barley, and oats any time after application. Plant sugar beets, winter rape, and canola 60 days after application, and all other crops 45 days after application.

Site of action Group 2: acetolactate synthase (ALS) inhibitor

Chemical family Sulfonylurea