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

Abstract

Field studies were conducted in Arizona in 1985-86 to investigate the propensity of 3 Deltapine cotton cultivars (DPL 61, DPL 77 and DPL 90) to produce 4-bract floral buds (squares) rather than the normal 3-bract squares, and to determine the susceptibility of 3- and 4-bract squares to damage by thrips. The primary thrips species found during the early season was Frankliniella occidentalis. Counts of Lygus spp. were low. Most squares (61-88%) had 3 bracts. Cultivar differences were found only in one test in 1986 in which DPL 77 produced a higher proportion of 4-bract squares than DPL 90. Square loss was compared in plots treated with insecticide (aldicarb and acephate) for thrips control and in untreated plots to determine any differential loss of either square type. Total square loss was higher in untreated plots for all cultivars tested during the early part of the season. The proportional loss of 4-bract squares was no higher and was sometimes lower than 3-bract loss. Abscised squares with enclosing bracts were more abundant than those with bracts open, whether in treated or untreated plots.