Established Crops, After Transplanting, or Preemergence Weed Control after Conifers Germinate

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.

Caution Do not apply to seedbeds.

Site of action (dimethenamid-P) Group 15: inhibits very-long-chain fatty acid synthesis; (pendimethalin) Group 3: microtubule assembly inhibitor

Chemical family (dimethenamid-P) chloroacetamide and (pendimethalin) dinitroaniline

flumioxazin (BroadStar, SureGuard SC)

Rate 150 lb/a

Time Apply after transplanting.

Remarks Irrigate within one hour after application to wash the herbicide from plants and activate the herbicide. Remove weeds and other debris from soil surface before applying.

Caution Do not apply to plants grown from seed unless one year old. Do not apply to moist or wet foliage. Do not apply more than 300 lb/a per year.

Site of action Group 14: protoporphyrinogen oxidase inhibitor

Chemical family N-phenylphthalimide

napropamide (Devrinol 50DF)

Douglas-fir, fir, and hemlock

Rate 4 lb ai/a (8lb/a Devrinol 50DF)

Time Apply any time to weed-free surface and irrigate immediately with 1 to 2 inches water.

Remarks Does not control emerged weeds. Consider use of several products at low rates to achieve broad-spectrum weed control. Inhibits root growth.

Site of action Group 15: inhibits very-long-chain fatty acid synthesis

Chemical family Acetamide

oxadiazon (Ronstar G)

Rate Consult label

Time Apply uniformly with granular applicator any time to weed-free surface. Irrigate with 0.25 to 0.33 inch water immediately after application.

Remarks Pink family (Caryophyllaceae) weeds-chickweed, mouseear chickweed, and pearlwort-are resistant. Controls weed seedlings by contact action during emergence.

Site of action Group 14: protoporphyrinogen oxidase inhibitor

Chemical family Oxadiazole

oxyfluorfen (Goaltender)

Rate 0.25 to 0.5 lb ai/a (0.5 to 1 pints/a) for 5-week-old seedlings; 1 to 2 lb ai/a (2 to 4 pints/a) for 2-0 conifers.

Time Apply at least 5 weeks after emergence. Apply to 2-0 conifers in winter dormancy fall through winter. After transplanting, irrigate with 0.5 to 0.75 inch water or rain for preemergence control of annual grass and broadleaf weeds. Do not exceed 2 lb ai/a per year.

Remarks Postemergence applications control susceptible broadleaf weeds up to 4 inches tall. Goaltender is a contact herbicide with some soil residual activity.

Site of action Group 14: protoporphyrinogen oxidase inhibitor

Chemical family Diphenylether

oxyfluorfen + prodiamine (Biathlon)

Rate Broadcast 2.75 lb ai/A (100 lb/a product). May be re-applied in 3 months. Do not apply over 200 lb/a per year.

Time Apply Biathlon prior to weed seed germination. For application in the fall, apply two weeks prior to placing plants in an empty, enclosed greenhouse structure.

Remarks Biathlon is applied as a broadcast application. Biathlon is a combination of herbicides containing two selective active ingredients that provide a broad spectrum of weed control with good plant tolerance on ornamentals. Prior to Biathlon application, irrigate with approximately ½ inch of water. For application in the fall, apply two weeks prior to placing plants in an empty, enclosed greenhouse structure.

Caution Do not apply to wet foliage. For use on evergreens (broadleaf and needle) but limited to Christmas tree and conifer farms.

Site of action (oxyfluorfen) Group 14: protoporphyrinogen oxidase inhibitor; (prodiamine) Group 3: microtubule assembly inhibitor

Chemical family (oxyfluorfen) Diphenylether + (prodiamine) Dinitroanaline

pendimethalin (Pendulum Aquacap or 2G)

Rate 2.1 to 4.2 quarts/a Aquacap; 100 to 200 lb/a 2G.

Time After transplanting, when soil has settled.

Remarks Will not control emerged weeds but will slow emergence if applied after weed seeds have germinated.

Caution Do not apply immediately after transplanting. Wait until the field is thoroughly packed and settled around the transplants. Do not apply during bud swell or bud break.

Site of action Group 3: microtubule assembly inhibitor

Chemical family Dinitroaniline

prodiamine (Barricade 4F)

Rate 0.66 - 1.5 lb ai/a (21 to 48 oz/a, and cannot
exceed 48 oz/a/year)

Time Apply any time after soil has settled around newly transplanted seedlings.

Remarks Activate herbicide with 0.5 inch irrigation within 14 days of application or before weed seeds germinate

Caution Do not exceed 2.3 lb ai/a per year in a given area

Site of action Group 3: microtubule assembly inhibitor

Chemical family Dinitroaniline

S-metolachlor (Pennant Magnum)

Rate 1.24 to 2.48 lb ai/a (1.3 to 2.6 pints/a Pennant Magnum)

Time Apply any time to weed-free surface.

Remarks Activate herbicide with brief irrigation. Use lower rates on porous media and reduced weed infestations. Gives about 60-day control, less under very wet conditions. Inhibits seedling roots and/or shoots.

Caution Do not exceed 4 lb ai/a per year in a given area. To minimize potential for crop injury, consider using several products at low rates to achieve broad-spectrum weed control.

Site of action Group 15: inhibits very-long-chain fatty acid synthesis

Chemical family Chloroacetamide