Field Bindweed and Canada Thistle

Summer fallow or postharvest

2,4-D amine (various trade names)

Rate 1.0 to 2.0 lb ae/A

Time Apply when weeds are in the bud to early bloom stage or while in good vegetative growth.

Remarks In the summer fallow year, cultivate until July 1, then let weeds re-grow to treatment stage. In the crop year, treat after harvest. Treat every year; skipping 1 year allows weeds to recover. Plant only labeled crops within 29 days following application. Do not apply more than 4 pints per acre per application. Make no more than two application per year.

Caution Do not let 2,4-D drift off target.

Site of action Group 4: synthetic auxin

Chemical family Phenoxy acetic acid

dicamba (Clarity and other trade names)

Rate 0.5 to 2 lb ae/A (1 to 4 pints/A Clarity)

Time Apply to fallow land, wheat stubble, or land to be rotated to wheat.

Remarks Control is best when weeds are actively growing in or beyond the full bloom stage. Make follow-up applications in spring to control seedlings. See label for crop use and crop rotation restrictions and for tank-mix recommendations.

Site of action Group 4: synthetic auxin

Chemical family Benzoic acid

glyphosate (various trade names)

Rate 1.5 to 2.3 lb ae/A (2 to 3 quarts/A of a 3 lb ae/gal formulated herbicide)

Time Apply in the fallow year. Best control is obtained when treatment is made at late growth stages approaching maturity.

Remarks Be sure to treat weed escapes in following years. To suppress Canada thistle, apply 0.75 lb ae/A plus 0.5 to 1% non-ionic surfactant in 3 to 10 gal/A water in late summer or fall after harvest, mowing, or tillage. Allow thistle rosettes to re-grow to at least 6 inches wide before treating.

Site of action Group 9: inhibits EPSP synthase

Chemical family None generally accepted

picloram (Tordon 22K and other trade names) + 2,4-D amine (various trade names)

Rate Suppression only: 0.125 to 0.25 lb ae/A picloram (0.5 to 1 pint/A Tordon 22K) + 0.5 to 1 lb ae/A 2,4-D. Spot treatment only: 0.25 to 1 lb ae/A picloram (1 to 4 pints/A Tordon 22K) + 1 to 2 lb ae/A 2,4-D.

Time In fallow, apply to actively growing plants in early bud to full bloom stage. Apply either early in the season or to re-growth following cultivation.

Remarks During crop year, treat soon after harvest when plants are still green and can easily be found. If picloram rate exceeds 0.25 lb ae/A, do not treat more than 10% of any given acreage per year. Do not apply by air if picloram rate exceeds 0.25 lb ae/A.

Caution Restricted-use herbicide. This treatment is likely to harm subsequent grain crop yield in treated areas for 1 year or more. Do not let picloram drift off target. Do not use in diversified cropping areas.

Site of action (both) Group 4: synthetic auxin

Chemical family (picloram) Pyridine; (2,4-D) Phenoxy acetic acid