BIOLOGICAL-CONTROL OF SENECIO-JACOBAEA IN NORTHERN CALIFORNIA, AN ENDURING SUCCESS

Senecio jacobaea, a poisonous weed from Eurasia, was brought under successful biological control in the Ft. Bragg, California area by 1976, through the combined action of the defoliating cinnabar moth (Tyria jacobaeae) and a root feeding flea beetle (Longitarsus jacobaeae). In 1987, 4 previously infested Ft. Bragg sites (3 sites where control had been documented and another unstudied site) were examined. Senecio jacobaea densities at these sites were 0.0, 0.0, 0.01 and 0.18 plants/m2, indicating both continued and improved control of the weed. The flea beetle and the cinnabar moth both persist at the sites, despite very low numbers of S. jacobaea plants. The control of S. jacobaea has resulted in the return of near natural vegetation at the 2 coastal prairie sites and regained productivity at the 2 pasture sites. © 1990 Lavoisier Abonnements.