ROW COVERS - EFFECTS OF WOOL AND ETHER MATERIALS ON PEST NUMBERS, MICROCLIMATE, AND CROP QUALITY

An investigation evaluating the potential of biodegradable woolen crop covers to protect vegetable crops from low temperatures, weed competi tion, and insect pests was conducted in the South Island of New Zealan d. Needle-punched wool felt covers were compared in a randomized block design experiment (3 replicates) containing 3 synthetic covers-spun-b ound polyester, polyolefin fabric, and. clear polythene-with uncovered pesticide-treated plots and control plots. The 21 plots each containe d 30 cabbage (cv. Derby Day) and 30 lettuce (cv. Great Lakes) plants. Numbers of aphids, Brevicoryne brassicae (L.); small white butterfly l arvae, Artogeia rapae (L.); thrips (Thysanoptera) larvae; and slugs, S arasinula plebeia (L.), were recorded on the plants 7 wk after plantin g. There were significantly more aphids recorded on cabbage plants ben eath the 80-g/m(2) wool than on plants in the other 6 treatments. This possibly was caused by the plants penetrating the 80-g/m(2) wool cove r, making them available to insect pests and thereby reducing the effe ctiveness of the product as a protective barrier fi om insect pests. N o plants penetrated the other covers tested. There were significantly fea er slugs under the wool cover (80 g/m(2)) than under the polyolefi n fiber cover. Higher and less variable temperatures were recorded und er the wool covers. The possible improvement of the wool cover by stre ngthening, and its commercial viability as a biodegradable row cover, are discussed.