Weed Management Handbook

glyphosate (several products)

Rate Wiper: 33% solution

Time Apply with selective wiper when weeds are at least 6 inches taller than crop but after active growth stage of conifer, when buds are mature.

Remarks Mix 1 gal product in 2 gal water. Avoid contact with desirable vegetation. Inhibits production of three amino acids and protein synthesis.

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.

dimethenamid-P + pendimethalin (Freehand 1.75G)

Rate 100 to 200 lb (1.75 to 3.5 lb ai/A)

Time Apply 3 days after transplanting conifers and prior to weed emergence.

Remarks Conifer species including Douglas-fir, western red cedar and western hemlock. Activate herbicide with brief irrigation. Inhibits seedling roots and/or shoots.

glyphosate (several products)

Rate Consult labels

Time Apply to emerged weeds just before conifer seedlings emerge using similar techniques described on the label under "cropping systems" for various cereal and vegetable crops.

Ammonium nonanoate (Axxe)

Rate A 10 to 13% volume to volume (v/v) dilution (13 to 16 fl oz per gal water) is recommended for most weed control situations and based on the results.

Time Apply to dry plant material, that will remain dry (no rain/no irrigation) for > 2 hr.

atrazine

Conifers only including Douglas-fir, grand fir, noble fir, Sitka spruce, and pine

Rate 2 to 4 lb ai/A

Time Apply October through March when trees are dormant.

Remarks Can be applied after small weeds emerge. Requires rain or sprinkler irrigation to activate. Apply only once per year.

dichlobenil (Casoron 4G)

Established stock only

Rate 4 to 8 lb ai/A (100 to 200 lb/A granular product)

Time Apply in midwinter immediately before a cold rain, to reduce volatility and to enhance weed suppression.

dichlobenil (Casoron 4G)

Rate 4 to 8 lb ai/A; 10 lb ai/A for nutsedge (100 to 200 lb/A Casoron; 250 lb/A Casoron for nutsedge)

Time Treat area before containers are set in midwinter when temperatures are cold and rain is expected immediately after application to activate herbicide and prevent loss by volatility.

Site of action Group 29: cellulose synthesis inhibitor

Ammonium nonanoate (Axxe)

Rate A 10 to 13% volume to volume (v/v) dilution (13 to 16 fl oz.per gal water) is recommended for most weed control situations and based on the results.

Time Apply to dry plant material, that will remain dry (no rain/no irrigation) for > 2 hr.

mulches

Rate On top of the soil, place 0.5 inches of non-decomposable mulch, such as hazelnut shells, sawdust, coco-fiber disks, geotextile disks, or any number of commercially available plastic disks, to prevent weeds from germinating and establishing in wet-dry cycles.

Time During container filling.