|Pitcairn, Michael - CA DEPT OF FOOD & AGRIC|
Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: October 6, 2000
Publication Date: January 1, 2003
Citation: Smith, L., Balciunas, J.K., Pitcairn, M.J. 2003. Biological control of yellow starthistle. Proceedings California Exotic Pest Plant Council Symposium. Vol. 6:2000,2001,2002.p.41. Interpretive Summary: Yellow starthistle is an important rangeland weed in the Western U.S.A. Previously released agents appear to be having little impact, except in Oregon, at low elevation sites with healthy grass communities. Biological control programs are being conducted to evaluate new natural enemies in the Mediterranean region and southern former U.S.S.R, where the plant is thought to have originated. European collaborators have conducted surveys to identify new prospective biological control agents. Recent experiments have identified several agents that are worthy of intensive evaluation to determine if they will be effective and safe to introduce.
Technical Abstract: Six insects that attack yellow starthistle have become established in California, but only two species are very abundant, and only the seedheads are attacked. Little impact on the weed has occurred except at low elevation sites in Oregon which are not overgrazed or disturbed (e.g., roadsides). Additional agents that attack the young plants are needed. Recent foreign exploration in turkey, Greece, Italy and southern Russia resulted in discovery of a root crown weevil (Ceratapion basicorne), a stem-boring beetle (Psylliodes sp. nr. chalcomera), a mite (Aceria sp.), and a lace plant bug (Tingis grisea). A rust pathogen (Puccinia jaceae) is in the final stage of approval for release in California. Many of these agents are being further evaluated for safety and potential efficacy.