Knotweed, Bohemian (Polygonum bohemicum), Japanese (Polygonum cuspidatum), giant (Polygonum sachalinense), Himalayan (Polygonum polystachyum), or fleeceflower

dicamba (Banvel, Rifle, or Clarity)

Rate 0.25 lb ae dicamba mixed with 1 gal water/400 sq ft

Time Apply in late August to new regrowth since plant was cut back in June.

Remarks Apply as a basal spray to the stems at ground level.

Caution Do not apply in areas where roots of desirable plant species are growing.

Site of action Group 4: synthetic auxin

Chemical family Benzoic acid

glyphosate

Rate Spot treatment: 0.06 lb ae (2.67 fl oz) glyphosate with 1 gal water

Time Apply as a coarse spray when weeds are actively growing and most are at bud to early flowering growth stage.

Remarks Spray for complete, uniform coverage but not to the point of runoff.

Caution Glyphosate is nonselective: it injures or kills any vegetation it contacts.

Site of action Group 9: inhibits EPSP synthase

Chemical family None generally accepted

glyphosate (Roundup Pro Concentrate)

Rate Inject 5 ml/stem

Time Inject with a hand-held device into hollow stem of actively growing plants between second and third internodes.

Remarks Mark each stem when making the injection to avoid reapplying.

Caution Non-crop use only. Total of all treatments must not exceed 8.5 quarts/a of Roundup Pro Concentrate or 1,600 stems/a per year.

Site of action Group 9: inhibits EPSP synthase

Chemical family None generally accepted

imazapyr (Arsenal or Habitat)

Rate 0.5 to 1 lb/a or 1% solution + 0.25% surfactant.

Time Apply in midsummer, after seedhead forms, up to killing frost.

Remarks Spray to cover plants but not to runoff. Habitat is labeled for aquatic sites.

Caution Before using, note crop rotation restrictions.

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

Chemical family Imidazolinone

triclopyr ester (Garlon 4 or Remedy) or triclopyr amine (Garlon 3A) or triclopyr + 2,4-D ester (Crossbow)

Rate 0.5% to 2% concentration for application with a handgun sprayer.

Time Apply to actively growing plants in midsummer.

Remarks Adding 0.25% to 0.5% of a suitable surfactant to Garlon 3A improves results. No surfactant is needed with Garlon 4 or Remedy.

Caution Garlon products are registered for use on rights-of-way, industrial sites, and forestry (release and site preparation). Crossbow and Remedy can be used on permanent pastures and rangeland up to 1.5 lb ae/a. Observe all grazing and harvesting restrictions.

Site of action Group 4: synthetic auxin

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