Potential for biological control of field bindweed in California's coastal vineyards

The possibility of using biological control against field bindweed, Convolvulus arvensis L., was studied in four vineyards along the California coast. Field bindweed is a dominant member of the weed community and the principal plant pest in these vineyards. There is considerable insect and mite damage to its foliage during late summer and autumn, but the stress this places on the weed is unknown. The most significant natural enemies of field bindweed are defoliating caterpillars, Bedellia somnulentella Zeller, Chaetocnema confinis Crotch, and spider mites. Non of the natural enemies present appeared to be suitable as biological control agents. However, some arthropods, such as Noctuelia floralis (Huebner), associated with field bindweed in Mediterranean Europe and Pakistan, could be useful in the California grape agroecosystem, once cleared for importation and release in North America. Others, unsuitable to release in California because of feeding on closely related native plants, may be of value in other parts of the world where no such conflicts of interest exist. It would be feasible to use biological control against field bindweed in California's coastal vineyards and, perhaps, also in orchards under present systems of cultivation. Its effectiveness could be enhanced by certain changes in growing practices, particularly the acceptance of some weed growth, and by changes in existing pest controls. Biological control of field bindweed should be considered in the development of pest management programs for such crops in California and wherever this plant is a serious pest.