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PNW CONSERVATION TILLAGE HANDBOOK SERIES
Chapter 5 - Weed Control, No. 6, Summer 1986


Control of Jointed Goatgrass in Dryland Cereal Grains

Don Wysocki

Jointed goatgrass is a winter annual weed that has become established and is spreading in many wheat producing counties in the Pacific Northwest. It is a close relative to wheat and has a very similar growth habit and seedling appearance, but has a distinct jointed spike. Goatgrass inhabits grain fields, road sides, rangeland, fence lines and drainageways. Kernels of goatgrass are very difficult to separate from wheat or barley seed through normal cleaning procedures. Consequently, goatgrass can be spread as a contaminant in seed lots in addition to other means. Research conducted by Don Rydrych, OSU weed scientist, Pendleton, has demonstrated that seven goat-grass plant per square foot in winter wheat can reduce yield approximately 27 bushels per acre.

Methods of Control

According to Rydrych, there are no highly effective selective chemical controls for goatgrass at this time. He has attained control levels of 70 to 80 percent with fall application of ethiozine, but these levels are not high enough for suppression. Therefore Rydrych has been exploring cultural methods to control goatgrass. He has studied the control of goatgrass under five different cropping treatments: (1) annual-crop spring wheat, (2) annual-crop winter wheat, (3) fallow winter wheat, (4) double-fallow winter wheat and (5) no-till winter wheat. The results for 1985, the first year of his study, are shown in Table 1. Effective control of goatgrass was obtained with the spring wheat treatment. Control in all winter wheat treatments, except the double fallow, was poor and infestation of goat grass remained high. And although not yet completed, the double-fallow rotation is effectively controlling goatgrass.

Rydrych concludes that tillage and rotation systems can be effective in reducing jointed goatgrass populations if for 2 years seedlings are not allowed to mature. If eradication is desired, the period must be extended to 3 or 4 years by using spring crops or double fallow. This means accepting lower economic returns (the yield difference between spring and winter grains and the income lost during double summer fallow) to attain eradication of goatgrass. On shallow soils, that have limited water storage capacity, Rydrych points out that spring cropping would be preferred over double fallow. Rydrych's work on cultural control of goatgrass will continue as will his efforts to develop an effective chemical control.

Table 1. Control of jointed goatgrass in cereal grains using different cultural practices (Rydrych, OSU, Pendleton, 1985 data).

Crop

Rotation

Goatgrass Control

(%)

Grain Yield1

(lb/acre)

Spring wheat Annual 99 2,260
Winter wheat Annual 3 3,590
Winter wheat Fallow 18 4,210
Winter wheat No-till 8 3,620
Winter wheat Double-fallow 95 -

1 Double-fallow wheat to be harvested in 1986.

Use of Trade Names

Research results are given for information only and are not to be construed as a recommendation for an unregistered use of a pesticide. Always read and follow label instructions carefully. To simplify the information, trade names have been used, Neither endorsement of named products is intended nor criticism implied of similar products not mentioned.

     
 

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