Integration of Prescribed Burning, Aminopyralid, and Reseeding for Restoration of Yellow Starthistle (Centaurea solstitialis)-Infested Rangeland

Abstract

AbstractYellow starthistle (Centaurea solstitialis) is among the most invasive plant species in the western United States. The long-term management of yellow starthistle should include an integrated approach that incorporates establishment of competitive vegetation. In this study, conducted in two locations at Fort Hunter Liggett in Monterey County, California, we evaluated the combination of prescribed burning, the herbicide aminopyralid, and reseeding of native broadleaf and grass species on both yellow starthistle control and native plant restoration. Both study sites were burned in late October 2009. Over the following season, aminopyralid was applied at three timings and native plant species were seeded at three timings, using both a drill-seeder and broadcast spreader. Evaluations over the next 3 yr showed that aminopyralid provided complete to nearly complete control of yellow starthistle when applied between January and March, and this level of control was maintained for two seasons. Native plants failed to establish when broadcast seeded, regardless of the timing. December and January drill seeding timings were the most successful in establishing native species. There was a strong herbicide and drill seed timing interaction effect on native grass cover at both study sites. Over the course of the study the native perennial grass Stipa cernua was the most successful seeded species to establish, but establishment was slow and required 3 yr. Our results indicate that a January or March aminopyralid treatment integrated with a native perennial grass drill seeding program in January offers the greatest probability of both successful yellow starthistle control and perennial grass establishment.