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WSU Advises, Begin Weed Control Before CRP Take-out

PULLMAN, Wash. — Farmers who plan to take land out of the Conservation Reserve Program this year should start weed control this spring, before removing land from CRP.

So advises Washington State University Weed Scientist Joseph Yenish.

More than 80 percent of CRP contracts in the Pacific Northwest will expire in 1997. Much of this land could be returned to crop production in 1997 and 1998 if growers are unsuccessful in bidding this land back to CRP.

“Growers should begin weed control efforts this spring, prior to CRP take-out, to minimize infestation in subsequent crops,” says Yenish.

“After years of no soil disturbance there is an opportunity to begin cropping CRP take-out fields with relatively low numbers of annual weeds. If the CRP field has infestation of downy brome (cheatgrass) or other annual weeds, growers should begin a weed management strategy to prevent further seed production starting this spring to reduce the soil seedbank before a winter wheat crop is established.”

Perennial weed patches can be identified and controlled through localized intensive management prior to CRP take-out.

Roundup or other formulations of glyphosate applied in the early spring can effectively prevent seed production in downy brome and other annual weeds. Yenish cautions farmers to apply Roundup to dormant grass to avoid risk of injury to the grass.

Yenish says it may be too late for farmers in warmer areas of Washington to spray before CRP grass breaks dormancy, but there should be sufficient time to spray in cooler areas.

The Pacific Northwest “Weed Control Guide” and the herbicide label provide information on herbicide rates and other application considerations.

Yenish says downy brome seeds aren’t expected to survive longer than two or three years in the soil. Preventing downy brome seed production in the spring for one or more years prior to CRP take-out reduces the number of seeds in the soil and provides long-term weed management benefits.

Crop rotation is another important weed management consideration coming out of CRP. Growing a spring crop, such as wheat, barley, or canola, the first year after CRP allows effective downy brome control to further decrease the amount of viable seed in the soil before growing winter wheat.

Farmers can prevent seed production of annual weeds for three years by following a spring crop with another spring crop or fallow after “take out”.

Downy brome control by herbicides in a winter annual broadleaf crop, such as canola, also could effectively reduce seed production.

More information on tillage and residue management considerations for CRP take-out can be found in “Returning CRP to Crop Production –A Summary of 1994-96 Research Trials in Washington State” — the November 1996 PNW Conservation Tillage Handbook Series No. 16 in Chapter 2.

Copies are available from the Crop and Soil Sciences Department, P. O. Box 646420, WSU, Pullman, WA, 99164-6420. Telephone orders also are accepted. Call (509) 335-2915.

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