glyphosate
Rate 2.25 lb ae/A
Time Apply to actively growing milkweed that has reached the late bud to flower stage of growth.
Remarks Reported to control this plant, although data are lacking in the Pacific Northwest. Follow label instructions.
Site of action (glyphosate) Group 9: inhibits EPSP synthase; (picloram) Group 4: synthetic auxin
Chemical family (glyphosate) none generally accepted; (picloram) pyridine
imazapyr (Arsenal)
Rate 1 lb ae/A
Remarks Reported to control this plant, although data are lacking in the Pacific Northwest. Follow label instructions.
Site of action Group 2: acetolactate synthase (ALS) inhibitor
Chemical family Imidazolinone