Yellow starthistle (Centaurea solstitialis L.) is a winter annual that was accidentally introduced to the United States in the mid-1800s. It has since become one of the most widespread invasive broadleaf weeds on rangeland and natural areas in the United States.
Read on for summaries of published research and practical management tips.
Integration of prescribed burning, aminopyralid (Milestone® herbicide) and reseeding for restoration of yellow starthistle-infested rangeland
Guy B. Kyser, Arthur W. Hazebrook and Joe DiTomaso (2013-in press) Invasive Plant Science and Management (DOI: 10.1614/IPSM-D-12-00094.1)
A study was established at two locations at Fort Hunter Liggett (U.S. Army Training Center) in Monterey County, California in 2009. The combination of prescribed burning, application of Milestone herbicide at 3 fluid ounces/acre, and reseeding of native broadleaf and grass species on both yellow starthistle control and native plant restoration were evaluated over a three-year period. Results of the study indicate that a January or March application of Milestone herbicide 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.
Control of Yellow Starthistle (Centaurea solstitialis) and Coast Fiddleneck (Amsinckia menziesii) with Aminopyralid (Milestone® herbicide)
Guy B. Kyser, Vanelle Peterson, Steve B. Orloff, Steven D. Wright, Joseph M. DiTomaso (2011). Invasive Plant Science and Management: July-September, Vol. 4, No. 3, pp. 341-348. http://wssajournals.org/doi/abs/10.1614/IPSM-D-11-00002.1
This research paper reports on a compilation of several independent field trials comparing the efficacy of Milestone® (aminopyralid) and Transline® (clopyralid) herbicides on yellow starthistle. Results showed that Milestone herbicide is about four times more effective on yellow starthistle compared to Transline herbicide. In the Central Valley of California, complete yellow starthistle control was obtained with Milestone at 3 fl oz/A when applications were made from December through February (optimum timing). Although pre-emergence applications and late-season applications (rosette stage) also control yellow starthistle, those timings were less consistent at lower rates and therefore required higher rates as per label instructions. At two locations, control of the poisonous native plant coast fiddleneck was also evaluated. Unlike Transline, Milestone provided almost complete control of coast fiddleneck when applied in the winter growing season. Applications of Milestone at the rosette stage resulted in a two-fold increase in annual forage grass biomass the following year. Results indicate that Milestone® is an effective tool for the management of yellow starthistle and coast fiddleneck and could be incorporated into an integrated management program.