Germination and Stand with Cottonseed Treatment Fungicides: Formulations and Rates1

Obtaining a stand of vigorous seedlings is a major problem in cotton (Gossypium hirsutum L.) production. The purpose of this study was to determine the effects of fungicide formulations and concentrations applied to cottonseed on germination in the laboratory and on emergence and survival of seedlings in greenhouse and field tests. Germination percentages with standard procedures at two temperature regimes were similar for cottonseed treatment with different rates and formulations of captan, N‐[(trichloromethyl)thio]‐4‐cyclohexene‐1, 2‐dicarboximide, and carboxin, 5,6‐dihydro‐2‐methyl‐l, 4‐oxathiin‐3‐carboxanilide, alone and in combination. No fungicide seed treatment gave significantly higher germination percentage than captan 0.94 g ai/kg, the rate used commercially. Germination was higher for some fungicide seed treatments than for the control (untreated), but most responses were not significant. Initial seedling stands for the control and the captan seed treatments were higher in field than in greenhouse evaluations, but coating the seed with either carboxin or captan + carboxin gave higher initial stands in the greenhouse. Final stands for all treatments were higher in field because of lower disease pressure from Rhizoctonia solani and Fusarium spp. than in greenhouse tests. Both pre‐ and post‐emergence damping‐off were more severe in green. house than in field tests. Slightly higher stands were obtained with the high rate of the fungicide seed treatments. All formulations of each fungicide gave similar results when used at comparable rates of active ingredient. Carboxin was superior to captan in increasing plant populations under severe disease infestations. Stands were higher for captan + carboxin than for either fungicide used alone but were lower than the sum of the effects of each fungicide alone.