SARE 1996 Highlights

Soil Microbes Curb Damaging Weeds

Naturally occurring soil bacteria can help tame a noxious weed that costs wheat farmers $145 million in yield losses annually, cutting-edge research in Washington state has shown. Jointed goatgrass infests 5 million acres nationally and is spreading. The close relative of wheat is difficult to control and its seeds are hard to separate from small grain at harvest. Winter wheat research provided a control clue that soil microbiologist Ann C. Kennedy pursued in a SARE-funded project. Her finding: Selected bacterial strains can inhibit root growth of a specific weed such as goatgrass. Surface spraying a combination of the three best strains in fall when planting winter wheat prevents 30 to 75 percent of aboveground growth of goatgrass, four years of research station trials showed. The soil bacteria flourish in cold weather and produce a compound that slows the weed's root growth, allowing the crop to compete better. Following up with small doses of low-toxicity herbicides provides additional weed control, Kennedy's research team has found. The scientists hope to do larger on-farm trials as part of an ongoing national program to manage goatgrass. They want to increase the survival rate of the bacteria, which die out in summer. The microorganisms are easy to manufacture, and this research could lead to an inexpensive, ecologically sound weed-control product within 10 years. (Western Region project AW91-5)

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