New growth regulator herbicide provides excellent control of yellow starthistle
AuthorsJoseph M. DiTomaso
Guy B. Kyser
Steve B. Orloff
Stephen F. Enloe
Glenn A. Nader
Authors AffiliationsJ.M. DiTomaso is Non-Crop Extension Weed Ecologist, Department of Vegetable Crops, UC Davis; G.B. Kyser is Staff Research Associate, Department of Vegetable Crops, UC Davis; S.B. Orloff is Farm Advisor. Siskiyou County; S.F. Enloe is Graduate Student, Department of Vegetable Crops, UC Davis; G.A. Nader is Farm Advisor, Sutter-Yuba-Butte Counties.
Hilgardia 53(2):12-16. DOI:10.3733/ca.v053n02p12. March 1999.
Yellow starthistle is the most widespread invasive weed in California. An exotic that invaded California in the Gold Rush days, starthistle was once a minor annoyance but is now out of control. One reason is that few herbicides are registered for use on California rangelands, pastures and wildlands. Of the registered herbicides, the majority are effective only when applied to the foliage of target plants; season-long control of yellow starthistle is not provided because seedlings that emerge after application of the herbicide escape injury. In a comparison of herbicides, the newly registered herbicide clopyralid provided excellent control at low use rates and worked eaually well whether applied to leaves or to soil to control germinating seedlings. In soil, it showed residual activity throughout the season. Complete yellow starthistle control was achieved with applications made from December through April, but treatments in February maximized desirable forage production, particularly grasses. Late-season applications of glyphosate and clopyralid were effective for control of starthistle plants in late rosette and bolting stages.
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Also in this issue:Biological studies of iceplant scales, Pulvinariella Mesembryanthemi and Pulvinaria delottoi (Homoptera: Coccidae), in California
Expanded efforts needed to limit exotic pests
Introduction Special section: exotic pest update
AHB headed to Central Valley?
Fire ant invades Southern California
Medfly - going but not gone
Can integrated methods stop starthistle?
Two new seed head flies attack yellow starthistle
Success of mowing to control yellow starthistle depends on timing and plant's branching form
A new sharpshooter threatens both crops and ornamentals
Glassy-winged sharpshooters expected to increase plant disease
Early results suggest sterile flies may protect S. California from medfly
Geographic races may exist among perennial grasses
Microsprinklers wet larger soil volume; boost almond yield, tree growth
Improving irrigation systems conserves water in greenhouse-grown cut flowers