Field bindweed in California
Biological control is seldom attempted against weeds on cultivated lands, because herbicides generally provide economical, efficient control, and farming practices may interfere with the biological agents. Field bindweed, however, reproduces from seeds that may remain alive in the soil for more than 40 years and from an extensive perennial root system. Control by cultivation or chemicals is difficult, at best. A search for biological control agents therefore seemed warranted. Even if such agents were effective only on field bindweed growing along roadsides and in other uncultivated areas, they would reduce the weed's potential for further invasion of cultivated land. A cooperative U.S. Department of Agriculture and University of California project was begun in 1970 to find biological agents for control of field bindweed.