Silverleaf whitefly colonization and trichome density relationship on upland cotton cultivars

We conducted studies to determine if morphological leaf surface features of cotton, Gossypium hirsutum L., are related to host plant resistance traits to silverleaf whiteflies, Bemisia argentifolii Bellows and Perring. Cotton cultivar Stoneville 474 had higher numbers of silverleaf whitefly eggs, ny mphs, and adults and also had higher numbers of stellate trichomes on abaxi al leaf surfaces compared with nine other upland cotton cultivars tested. T he five smooth, okra-leaf cotton cultivars as a group had similar numbers o f whitefly eggs (25) and nymphs (10) per cm(2) of leaf disk but fewer adult s ( 12) per leaf compared with four smooth, normal-leaf cotton cultivars. T he top young leaves on the main stem terminals of smooth normal- or okra-le af cultivars had significantly higher numbers of stellate trichomes (174) p er cm(2) of leaf disk compared with older leaves. However, the top young le aves on main stem leaf nodes #1 also had reduced numbers of eggs (23) and n ymphs (1) per cm(2) of leaf disk compared with older leaves (17-81 and 14-2 6, respectively). Results suggest that other Factors, in addition to leaf h airiness, at least For young terminal leaves, affect silverleaf whitefly po pulations.