Biological Control of Russian Thistle Along California Highways.

摘要

The objective of this research project was to develop a program to control Russian thistle with insects. Recent records indicate control and clean-up operations against Russian thistle cost Caltrans approximately 1.5million dollars annually. To date,two species of moths have been released and are established on the plant. Coleophora parthenica,whose larvae feed inside the stems was first released in 1973and is now widely established. High larval populations are causing stunting and reduced seed production by the plants in some areas. This program has reached the operational stage,and a large scale redistribution program was conducted with this moth during 1977-78. The second moth, Coleophora klimeschiella,whose larvae attack the foliage was released in 1977. It is well established in the field,but populations are still too small to allow for large scale redistribution. This moth should work better in cooler areas,where C. parthenica appears to be of limited value.