Evaluation of Spunbonded Polyethylene Row Covers as a Method of Excluding Insects and Viruses Affecting Fall-Grown Squash in Florida

Abstract

A lightweight floating row cover, used alone and in combination with a white-on-black polyethylene mulch, was evaluated under the hot, humid conditions of the fall growing season in Florida as a method of controlling aphid-borne mosaic viruses, whitefly-induced leaf silvering, and insects directly damaging zucchini squash. Yields increased dramatically with the use of covers, especially if covers were left in place for at least 1wk after plants began to bloom. Covers excluded pickleworm, Diaphania nitidalis (Stoll); melonworm, Diaphania hyalinata (L.); sweetpotato whitefly, Bemisia tabaci (Gennadius), and several colonizing aphid species. Except for B. tabaci, insects colonized newly uncovered plants slowly, remaining at low densities for up to 2 wk after removal of covers. Few winged aphids landed in water pan traps placed over covers, which may explain why aphids and aphid-vectored viruses remained at low levels even when covers were torn. Incidence of potyviruses and silverleaf was greatly reduced by use of row covers, but symptoms of viral infection developed 1-2 wk after removal. If used over an entire planting, high levels of inoculum presumably would not develop, and viral infection might be delayed even longer.