Rubber Rabbitbrush Control Using a Combination of Mowing and Various Herbicide Treatments

Project ParticipantsChad Reid and Dean Winward

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Rabbitbrush (Chrysothamnus spp.) is a genus of native shrubs that are common in many plant communities throughout the western United States. The genus Chrysothamnus contains 16 species and 41 subspecies, three of these species dominate in terms of distribution: Douglas rabbitbrush (C. viscidiflorus), Parry rabbitbrush (C. parryi); and Rubber rabbitbrush (C. nauseosus; photo left). 
All species of rabbitbrush are very prolific seed producers and can be extremely invasive, particularly in disturbed areas such as abandoned homesteads or rangeland seedings. Management of rabbitbrush is difficult because it is deep rooted and sprouts vigorously after disturbance such as fire or mechanical treatments. Many treatments and combination of treatments have been tried with little success or with highly variable results. Effective practical treatments have so far eluded range managers or landowners. Multiple treatments combining fire, mechanical removal, or herbicides in various combination have shown promise for control. 
Recently, the authors used a multiple treatment mower that windrows the woody debris, then the wipes the herbicide onto the cut shrub stubble. Pilot treatments applied in Fall 2005 showed promising results with Tordon (picloram) and Vanquish (dicamba) at rates as low as one quart per acre providing near 100% control. Curtail (clopyralid), 2,4-D and mowing alone provided no control. In 2006 and 2007, replicated plots were established at the SUU Valley Farm in Cedar Valley. Milestone (aminopyralid), a new herbicide, was substituted for Curtail and 2,4-D was dropped from the treatments because of poor results in the pilot plots.
Study results for 2006 and 2007 are reported in the tables below:

Chad Reid
Natural Resources/Agriculture Agent
USU Extension - Iron County
P.O. Box 69
Cedar City, UT

Dean Winward
Associate Professor
Southern Utah University
Agriculture and Nutrition Science Department
Cedar City, UT