Weed control in squash and tomato fields by soil solarization in the Jordan Valley

Black (BPE) and clear polyethylene mulches (CPE), 0.08 and 0.06 mm thick, respectively, were compared for their effectiveness for soil solarization over three seasons during 1986–1989 in weedy fields. Solarization for 6 weeks reduced weed growth and enhanced crop yields. However, further mulching with BPE after solarization with either BPE or CPE gave the best results. Not all weeds were sensitive to solarization. Some weed species were completely controlled; others were reduced to varying degrees; yet other weed species seemed to be enhanced by solarization. Solarization without further mulching was no better than farmer-practice in reducing weed growth or in increasing crop yield. Weeds required further removal after the middle of the growing season. Any soil disturbance after solarization reduced the weed control effect of solarization. Crops grew best in plots after solarization with BPE if they were planted in the same mulch after it was perforated.