Cotton, Gossypium spp., breeding for resistance to leafhoppers of genus Empoasca and to sweetpotato whitefly, Bomisia tabaci (Gennadius poses a dilemma for the cotton breeder. Glabrous (smoothleaf) cotton plants have higher leafhopper populations but fewer whiteflies and less leaf and bract trash in mechanically harvested seedcotton than plants with pubescent leaves. In this study, both leafhopper and whitefly populations were observed in 31 cotton entries planted at Bet She'an, Isreael in 1987.

Leafhopper populations decreased but the whitefly populations increased as the cotton leaf pubescence increased. At the end of June, plants with about 40 trichomes per 13.7 mm supported relatively low populations of both leafhoppers and whiteflies. However, the whitefly populations increased later in the season to 43X the earlier population levels. whitefly populations increased as the number of trichomes increased up to 70 trichomes per 13.7 am and then decreased as the trichomes became more dense. Various control measures and breeding schemes that might interact to provide an answer to the control of these pests are discussed.