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Proper grazing management can minimize spread and help manage invasive weeds on rangelands. Some scientists are taking grazing to the next level by prescribing grazers to manage invasive weeds.
Compared to cattle, sheep are more willing to eat weedy forbs like knapweeds, leafy spurge, whitetop, and others. Scientists continue to study how to best use this knowledge in the fight against these invaders. One strategy under the microscope is short-term, high intensity sheep grazing. Scientists have found that if more sheep are confined to less area for a shorter time, they eat more of the invasive weed leafy spurge. This can offer a cheaper control alternative. In addition, using sheep for weed control creates a product (wool, meat, etc.) from an unwanted weed.
It’s been said that goats are garbage cans with legs. While this is somewhat exaggerated, goats are very adept at using ‘low quality’ vegetation. Goats have a relatively large liver that may equip them to better handle chemicals in some weeds that discourage herbivory. They also are more willing to tackle plants with sharp spines. While they preferentially browse woody vegetation, they also readily eat leafy spurge, perennial pepperweed, and other invasive weeds. When combined with herbicide or other control methods, management can be more successful.
Where cheatgrass dominates, fires occur frequently. Using this knowledge, researchers are studying whether intensive cattle grazing is a cost-effective method to reduce fuel loads and minimize fire spread.
Here’s how it works:
Cattle are being allowed to intensively graze plots of cheatgrass-infested rangeland while it is still green and palatable. This reduces the amount of vegetation and thus lowers fuel available to carry a fire. On a larger scale, this might have application in creating fire breaks to reduce the spread of a fire. This intensive grazing may also serve as a method for reducing the seed bank of cheatgrass.
Similarly, researchers are using cattle to graze old strips of crested wheatgrass planted as fire barriers. Over time, these ‘greenstrips’ of crested wheatgrass become laden with old growth, making them ineffective at stopping or slowing fire. Grazing cattle may rejuvenate these stands, increasing their effectiveness.
-Call, C. 2006. Personal communication. Research: Using cattle as fuel reduction agents in annual and perennial grass stands in northern Nevada (October 24, 2006).
-Dale-Cesmat, C. 2004. A control study: Using goats to control perennial pepperweed in Lassen County. Noxious Times: a quarterly publication of the California Interagency Noxious Weed Coordinating Committee. Vol. 6 No. 1 pp. 10-12.
-DiTomaso, JM., G.B. Kyser, S.B. Orloff, and S.F. Enloe. 2000. Integrated strategies offer site-specific control of yellow starthistle. California Agriculture. Vol. 54 No. 6 pp. 30-36.
-Frost, R.A. and K.L. Launchbaugh. 2003. Prescription grazing for rangeland weed management. Rangelands. Vol. 25 No. 6 pp. 43-47.
-Kirby, D.R., T.P. Hanson, and C.H. Sieg. 1997. Diets of angora goats grazing leafy spurge (Euphorbia esula)-infested rangeland. Weed Technology. Vol. 11 pp. 734-738.
-Olsen, B. 1999. Manipulating diet selection to control weeds. Presented in "Grazing Behavior of Livestock and Wildlife." Idaho Forest, Wildlife & Range Exp. Sta. Bull. #70, Univ. of Idaho, Moscow, ID. Editors: K.L. Launchbaugh, K.D. Sanders, J.C. Mosley.