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P N W 0 256
JOINTED
GOATGRASS
A Pacific Northwest Extension Publication " ' Washington Oregon Idaho
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Leafhairs. Note the hairs on the auricles and the evenly spaced hairs on the leaf edges.
Dean G. Swan, Extension Weed Scientist Washington State University
Jointed goatgrass (Aegilops cylindrica) is a winter annual grass that has been introduced into the winter wheat producing areas of the Pacific Northwest. This weed is found in wheat fields, grasslands, along roadsides, fencerows, and other cropped and noncropped areas. It was introduced from Europe early this century. Jointed goatgrass competes with winter wheat for nutrients, moisture, and sunlight. Grain that contains jointed goatgrass cannot be certified and is subject to being docked at the elevator.
F. L. Picket, botanist, was the first to collect jointed goatgrass for
the herbarium at Washington State College. The specimen was collected in 1917 from Rogers Field. The
oldest plant at the University of
Idaho herbarium was collected in
1952. The first specimen at Oregon State's herbarium was collected from the 'Baker area in 1956.
Jointed goatgrass heads. The center head has been disjointed.
Jointed goatgrass looks like wheat except for the head. Leaves are alternate, simple, with auricles at the base of the blade. The auricles are hairy and the blades have evenly spaced hairs along their edges (Figure 1). The spikelet has from two to four flowers that are arranged in a cylindrical spike. The glumes on the uppermost spikelet have long awns. Seed ripens before the winter wheat and shatters easily (Figure 2). Each seed "joint" generally has from one to three viable seeds (Figure 3). These mayor may not germinate at the same time (Figure 4).
Studies indicate jointed goatgrass germinates best at temperatures between 50° and 86°F. Some germination will occur as low as 36°F and as high as 104°F.
Left- jointed goatgrass "joints':' right-jointed goatgrass seed from a "joint." Scale- Xs in. (1 mm)
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Figure 4
Jointed goatgrass seedlings. Note the multiple sprouts from one 'Joint. "
Jointed goatgrass seedling looks similar to a wheat seedling. For identification, dig the plant and look at the seed.
Figure 6
Wheat infested with jointed goatgrass.
Jointed goat grass will emerge readily from 2 to 4 inches deep in
'the soil and can emerge from as deep as 5 inches (Figure 5). Some seed buried 9 inches deep in the soil was still viable after 3 years.
The seed 'Joints" are difficult to separate from wheat and no method is 100% efficient.
Research studies have shown that
one jointed goatgrass plant per square foot can reduce wheat yields by 3 to 5%. Thus, 10 p\ants per square foot can reduce yields by 30 to 50% (Figure 6).
Jointed goatgrass will cross with wheat (Figure 7). However, the cross rarely forms seed and when it does, most seeds are sterile.
Left-jointed goatgrass head; right-wheat head; center-two
jointed goatgrass/wheat crosses.
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Jointed goatgrass has been spreading rapidly and is now widely distributed in the Pacific Northwest. In a USDA survey it was reported to occur in all the wheat growing counties of eastern Washington. Seed certification inspectors report that few winter wheat fields are free of jointed goatgrass. Ironically, farmers themselves are helping spread jointed goatgrass seed.
Oregon researchers conducted a drill box survey and found jointed goatgrass seed in the wheat seed in
one drill out of every five inspected. This means that farmers were seeding 20% of the wheat acreage with jointed goatgrass-infested wheat
seed. Contaminated equipment, hay, clothing, etc. also help spread the weed.
We have tested more than 30 herbicides using eight different systems for jointed goatgrass control. We found most did not give satisfactory control, caused crop injury, or both. One herbicide, metribuzin, showed promise. When applied preplant, followed by deep furrow seeding, weed control averaged 75%. The deep furrow seeding moved the treated soil to the sides and onto the ridge, and the wheat was planted in the bottom of the chemical-free furrow. However, when this system was tested on hillsides the treated soil tended to move back into the furrow and damage the wheat crop.
Rotating to a spring crop, especially spring barley, gave 95% jointed goatgrass control. Some growers have managed to control jointed goatgrass by growing two spring crops, followed by a summer fallow, then back to winter wheat. It is important to keep spring crops in
the rotation long enough to germinate most of the jointed goatgrass seed in the soil. This weed is an annual and can only remain a problem by shedding seed back to the soil. Anything that prevents seed production will help solve the problem.
Directed or shielded herbicide spray gave 75% jointed goatgrass control. This was accomplished by using drop nozzles or fenders and spraying with paraquat between the deep furrow seeded 14- or 16inch wheat rows. Research efforts are continuing.
1. Prevent infestations. Use crop seed, hay, and straw that is free of jointed goatgrass seed. Clean equipment before moving from a jointed goatgrass-infested area.
2. Prevent jointed goatgrass from going to seed along edges of fields and roadways. Mowing to keep the weed from going to seed, plus establishing a competitive perennial grass, is the best way to keep jointed goatgrass under control in these areas. You can establish perennial grass after chemical or mechanical summerfallowing for one season. This controls weeds and conserves moisture and you can seed a desirable grass the following fall. In the higher rainfall areas, fallowing may not be necessary.
3. When harvesting wheat in infested fields, reduce the air on the combine and cut low to insure that most jointed goatgrass seed is harvested. Use a straw and chaff catcher on the combine in the problem areas and remove all seed-infested chaff and straw from the field. The jointed goatgrass seed will then be in your bin, chaff, or straw and not back in your field. You
can't perpetuate jointed goatgrass in your field without the seed.
4. Change cropping sequence for at least two out of three crop years. Plant a spring-seeded barley or wheat. Spring barley appears to be the better competitor.
5. For fall seeding, delay planting as long as possible and plant clean wheat seed. Rod weed or treat the first flush of jointed goatgrass seedlings with glyphosate or paraquat just before seeding. This will insure good control of this early weed flush. If rain occurs near planting time, wait a few days for the jointed goatgrass seed to germinate. The seedling plants can be controlled by tillage or herbicides before planting wheat. Future emergence of jointed goatgrass i seedlings will then be less severe.
Pacific Northwest Cooperative Extension bulletins are joint publications of the three Pacific Northwest states-Washington, Oregon, and Idaho. Similar crops, climate, and topography create a natural geographic unit that crosses state lines. Since 1949, the PNW program has published over 200 titles. Joint writing, editing and production has prevented duplication of effort, broadened the availability of faculty specialists, and substantially reduced costs for the participating states.
Published and distributed in furtherance of the Acts of Congress of May 8 and June 30,
1914, by Washington State University Co
operative Extension, J.O. Young, Director;
the Oregon State University Extension Service, O.E. Smith, Director; the University of Idaho Cooperative Extension Service, H.R. Guenthner, Director; and the U.S. Department of Agriculture cooperating.
The three participating Extension Services offer educational programs, activities, and materials without regard to race, color, national origin, or sex as required by Title IV of the Civil Rights Act of 1964 and Title IX of the Education Amendments of 1972. The Washington State University Cooperative
Extension, Oregon State University Extension Service, and University of Idaho Cooperative Extension Service are Equal Opportunity Employers. Published July 1984. .50/.50/.50
Cover picture-Jointed goatgrass plant.