Influence of Tillage, Seed Quality, and Fungicide Seed Treatments on Cotton Emergence and Yield

Seedling diseases of cotton (Gossypium hirsutum L.) limit production in the High Plains of Texas. Field studies were conducted from 1992 through 1995 to determine the influence of tillage (conventional or terminated wheat [Triticum aesrivum L.] conservation tillage system), seed quality, and fungicide seed treatments (specific for Rhizoctonia solani, Pythium spp., and Thielaviopsis basicola) on cotton emergence and lint yield. Seed quality positively affected plant emergence and yield in all years. Increases in plant emergence and yield were generally found with conventional rather than conservation tillage. Emergence 21 d or later was generally lower for untreated seed or Captan (C) (N-trichloromethylthio-4-cyclohexene-1,2-dicarboximide) treated seed than seed treatments that included triadimenol (Baytan 30 [B]) (Beta-(4-Chlorophenoxy)-alpha-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol) in 3 of 4 yr; carboxin-PCNB (Vitavax-PCNB [V]) (5,6-dihydro-2-methyl-N-phenyl-1,4-oxathiin-3-carboxamide-Pentachloronitrobenzene) in 2 of 3 yr and metalaxyl (Apron 2.66F [A]) (N-(2,6-dimethyl-phenyl)-N-(methoxyacetyl)alanine methyl ester) + C in one year. Yields were affected by seed treatments in 3 yr, with B being associated with higher yields every year, and lower yields associated with chloroneb (Nuflow ND [N]) (1,4-dichloro-2,5-dimethoxybenzene) + TCMTB (2-(thiocyanomethylthio) benzothizaole (1992), untreated seed (1994) and C (1995). Plants were infected most frequently with R. solani and T. basicola. The most consistent factor affecting seedling disease was seed quality. Conventional tillage and seed treatments specific for Rhizoctonia and Thielaviopsis improved seedling emergence and yield most years. Interactions between chemical seed treatments, seed quality, and tillage systems were inconsistent between years and even among different evaluation times in the same year. Research QuestionWhat are the effects of chemical seed treatments, tillage system, and seed quality, interactions as well as separate effects, on seedling emergence and cotton yield. Literature SummaryEvidence has shown that seedling disease can be higher under conservation tillage systems than conventional tillage systems. Cotton seedling emergence can be affected by seed quality and some seed treatment fungicides. However, interactions between these factors have not been studied. The impact of tillage systems on seedling emergence when seed quality varies, or with different seed treatments, is unknown. The question of whether use of new fungicides with moderate or low quality seed will adversely affect emergence is of great interest to producers. Study DescriptionThis field study was conducted from 1992 to 1995 on land that had been in either conventional tillage or conservation tillage (cotton drilled into terminated wheat) since 1986. Within each conventional or conservation tillage area, treatments consisted of three levels of seed quality and five to six fungicide seed treatments, specific for certain pathogens. Cotton emergence was monitored weekly and plots were harvested for yield. In 1994–1995, cotton roots were examined for disease symptoms, and pathogens were isolated. Applied QuestionsWere cotton emergence and yield responses from seed of different quality similar in conservation and conventional tillage treatments? Cotton emergence was positively associated with seed quality, for both conservation and conventional tillage systems. Emergence was higher in conventional tillage plots for each seed quality level than in conservation tillage plots in 2 of 4 yr. Was cotton emergence affected by new fungicide seed treatments interacting with tillage practices? Tillage did not have a consistent influence on any particular seed treatment. Were cotton emergence and yield responses negatively affected by triadimenol (Baytan 30) when combined with lower quality seed? No. Triadimenol was associated with reduced early emergence with all seed quality levels, and superior, final emergence with all seed qualities as compared with untreated seed or Captan treated seed.