Susceptibility of Early Season Cotton Floral Bud Types to Thrips (Thysanoptera: Thripidae) Damage

Abstract

Because of suggestions that four-bract floral buds (squares) are more vulnerable to thrips (Thysanoptera: Thripidae) injury than three-bract squares, we evaluated ‘Deltapine’ (DPL) cotton ( Gossypium hirsutum L.) cultivars ‘61,’ ‘77,’ and ‘90,’ for production and susceptibility of square types during the 1985-1986 early squaring period. Most squares (61-88%) had three bracts. Cultivar differences were found only in one test in 1986 in which DPL ‘77’ produced a higher proportion of four-bract squares than DPL ‘90.’ Square loss was compared in plots treated with insecticide for thrips control and in untreated plots to determine any differential Joss of either square type. Total square loss was higher in untreated plots for all cultivars tested during the early part of the season. Proportional loss of four bract squares was no higher and was sometimes lower than three-bract loss. Abscised squares with enclosing bracts were more abundant than those with bracts open, whether in treated or untreated plots.