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.