W. L. Parrott

FACTORS CONTRIBUTING TO RESISTANCE AND SUSCEPTIBILITY OF COTTON AND OTHER HOSTS TO THE BOLL WEEVIL, ANTHONOMUS GRANDIS

A large portion of the worlds germ plasm of cotton has been screened at the USDA Boll Weevil Research Laboratory, State College, Mississippi during the period 1962–68 utilizing developed techniques.

Breeding upland cotton for resistance to the tarnished plant bug

Abstract The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), reduces yield and delays maturity in cotton, Gossypium hirsutum L., in many parts of the southeastern cotton belt. The objectives of this study were: a) to determine the response of six cotton strains to this pest; b) to obtain information on gene action conditioning this response to tarnished plant bugs; and c) to select progeny in the presence of tarnished plant bugs for early-season yielding ability. The six strains evaluated were: Bulgarian 3279, Deltapine 7146N, DES-06, ORH 78-75, Stoneville 213 frego, and Coker 420 smooth nectariless. The four crosses utilized were: Deltapine 7146N X Bulgarian 3279 (cross 1), Stoneville 213 frego X Bulgarian 3279 (cross 2), Coker 420 smooth nectariless X ORH 78-75 (cross 3), and DES-06 X ORH 78-75 (cross 4). Resistance is based on the relative seedcotton yield and yield loss at first harvest in unsprayed plots as compared to insecticide-treated plots. Generation-mean analyses indicate that crosses 1,2, and 4 appear to have genes segregating for resistance to the tarnished plant bug. Dominant gene action was primarily responsible for seed-cotton yield and percentage of total seedcotton at first harvest (earliness), and boll weight. Inheritance of lint percentage was primarily additive. Several selected progeny tested under plant-bug infestations produced higher seedcotton yields at first harvest than their higher-yielding parent or control cultivar. Early maturity (higher percent of total seedcotton at first harvest) was maintained in most selections when plant bugs were present. Growing progeny under high levels of plant bugs allows both the elimination of the most susceptible lines and the identification of lines with resistance to the tarnished plant bug.