Effects of Row Spacing and Cotton Cultivars on Seedling Diseases, Verticillium Wilt, and Yield1

Abstract

Cotton (Gossypium hirsutum L.) cultivars ‘Rilcot 90’ (susceptible to Vertkillium wilt) and ‘Paymaster 266’ (resistant to Verticillium wilt) were grown in one, two, and four rows per bed spaced 100 cm apart to determine the effects of cultivars and row spacings on seedling diseases, Verticillium wilt, and yield. Each treatment was applied to the same plot for 3 consecutive years. Plant stands increased with close row spacings but were not directly related to the seeding rates. The prevalence of foliar symptoms of Verticillium wilt was higher in Rilcot 90 than in Paymaster 266, but the percentage decreased with close row spacing. The number of diseased plants of each cultivar was higher with closer row spacing but did not increase directly with plant populations. Lint yield was highest in plants having two rows per bed and lowest in those having one row per bed, but the differences were not significant. The high moisture level maintained during the growing season provided good conditions for disease evaluations but probably reduced lint yield.In the 4th year, each plot was halved. Seeds of the wilt‐susceptible ‘Lockett 4789A’ and of the wilt‐resistant ‘Paymaster 909’ were planted in one half of each plot in rows 100 cm apart. Stands were reduced slightly by seedling diseases. The prevalence of Verticillium wilt was lower when each cultivar was grown after Paymaster 266 rather than Rilcot 90. Close row spacing during the previous 3 years did not significantly increase the prevalence of Verticillium wilt. A disease‐resistant cultivar should be grown at high plant populations to minmize losses from Verticillium wilt and to maximize lint yields.