Perennial weeds respond to control by soil solarization

Soil solarization in summers in Central Valley and near-coastal sites controlled bermudagrass and johnsongrass covered by polyethylene tarps. Field bindweed was also controlled during solarization, but regrowth occurred. To maximize control and reduce the “edge” effect – the regrowth of weeds at the edges of fields when they are not covered by tarps – the soil must be completely covered with intact polyethylene.