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Abstract Detail

Ecological Section

Sommers, William D. [1], Howery, Larry D. [2], Lee, Richard D. [3], Pendleton, Rosemary [4], Pendleton, Burton K. [4].

Integrated Weed Management of Yellow Starthistle in Southwestern New Mexico.

YELLOW starthistle (Centaurea solstitialis L.) has become established within the Cliff-Gila River Valley of Grant County, New Mexico. This aggressive noxious weed forms dense stands that displace native plants and reduce native plant and animal diversity. While control methods have been developed for California and the Pacific Northwest, different climatic conditions of the arid Southwest pose unique challenges. This study examines the use of fire, herbicide application, grazing, mowing and reseeding with native perennial grasses in an integrated weed management experiment. Revegetation and weed suppression treatments were applied to a heavily-infested pasture in a completely randomized split-plot design. The entire 100-acre pasture was burned in April, 2002, followed by reseeding of whole plots using one of four native grasses. Weed suppression treatments were applied to subplots the following year. Although the impact of prescribed fire on yellow starthistle was not quantified, both cover and density of starthistle was reduced for one year following the burn. Drought severely impacted both herbicide effectiveness and perennial grass establishment. Alkali sacaton failed to establish, and cover of the remaining three species was low. Western wheatgrass was the most successful grass, spreading rhizomatously and flowering by the summer of 2004. Of the suppression treatments, clopyralid was most effective at reducing starthistle cover and density, followed by 2,4-D and mowing. One year after treatment, however, density of yellow starthistle was still relatively high on all treatment plots. The advent of July rains following herbicide and mowing treatments resulted in rapid regrowth of yellow starthistle. Drought and the monsoonal moisture regimes of the Southwest will require modification of existing recommendations for the timing and frequency of weed suppression activities. Effective restoration of starthistle-impacted lands in the Southwest will entail multiple years of suppression treatments, careful monitoring of starthistle regrowth and the reestablishment of native species.

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1 - Arizona State Land Department, 809-C Gail Gardner Way, Prescott, Arizona, 86305, USA
2 - University of Arizona, School of Natural Resources, Tucson, Arizona, 85721, USA
3 - USDI Bureau of Land Management, National Science and Technology Center, P.O. Box 25047, Denver Federal Center, Denver, Colorado, 80225-0047, USA
4 - USDA Forest Service, Rocky Mountain Research Station, 333 Broadway SE, Suite 115, Albuquerque, New Mexico, 87102-3497, USA

Centaurea solstitialis.

Presentation Type: Poster:Posters for Sections
Session: 48-44
Location: Auditorium/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 12:30 PM
Abstract ID:65

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