Postemergence Weed Control

clethodim (Envoy)

Consult label for tree species

Rate 0.095 to 0.25 lb ai/a (13 to 34 oz/a Envoy)

Time Apply postemergence to actively growing annual or perennial grasses listed on label.

Remarks Consider environmental and plant growth conditions that affect leaf uptake; see label.

Caution Do not exceed 68 fl oz/a per season.

Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor

Chemical family Cyclohexanedione

lactofen (Cobra)

Rate 0.10 to 0.25 lb ai/a (6.5 to 16 fl oz/a)

Time Apply when weeds are actively growing but are less than 4 inches tall, and when the primary shoot of the conifer has hardened off.

Remarks Cobra is a contact herbicide with some soil residual activity. Do not apply with adjuvants when shoots are young and have not hardened off.

Site of action Group 14: protoporphyrinogen oxidase inhibitor

Chemical family Diphenylether

fluazifop (Fusilade II)

Rate Consult label

Time Apply to established ornamental seedbeds as topical or directed sprays according to lists and associated instructions on the label. Apply to actively growing grasses, or within 7 days after irrigation, with 0.25% nonionic surfactant.

Remarks Identify grasses and adjust rates for susceptibility and stage of weed growth as on label. Results often are erratic if grasses are stressed by lack of vigor, drought, heat, or low fertility. More mature grasses and quackgrass can be controlled but may need two applications. Annual bluegrass and all fine fescues resist treatment. Inhibits fatty acid production, cell membranes, and new growth.

Caution Do not tank-mix with other pesticides or apply within 5 days of other pesticide treatments. Grazing is prohibited.

Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor

Chemical family Aryloxyphenoxypropionate

sethoxydim (Segment)

Rate 0.28 to 0.47 lb ai/a (36 to 60 fl oz/a)

Time Apply at optimum growth stage listed on the label.

Remarks Identify susceptible grasses. Control often is erratic on grasses stunted or stressed from drought, high temperatures, or low fertility. Resistant grasses include annual bluegrass and all fine fescues, whereas quackgrass can be suppressed. Inhibits fatty acid production, cell membranes, and new growth.

Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor

Chemical family Cyclohexanedione