Goats help combat noxious weeds
Are goats the new warriors in Idaho’s battle with noxious weeds?

UI Extension Educator Shannon Williams, heading up three years of Lemhi County studies, finds that goats grazing during bud-to-bloom times significantly reduce seedhead production of spotted knapweed, found in all Idaho counties. Grazing also diminishes the viability of leafy spurge. In both cases, desirable grasses are not affected.

The study examined which stages of plant growth, when grazed, most dramatically decrease spotted knapweed seed production. At the budto- bloom stage, which lasts about three weeks, grazing showed a 73 percent reduction after year one, and a 93 percent reduction at year two, compared to control areas without goats.

Tests at the Salmon City Waterworks indicate that goats select spotted knapweed over grasses. In all, goats helped clean up 12,000 acres of Lemhi County leafy spurge and spotted knapweed. The study used about 50 goats to cover one acre per day, assuming an average weed density.

Studies involving sheep are also underway. All grazing studies seek effective alternatives to spraying and biological controls, since not all places with noxious weeds can use those techniques. Contact Williams at shannonw@uidaho.edu.

--by Amanda DeRuwe

© 2004 University of Idaho, College of Agricultural and Life Sciences.