Jason E. Woodward1, Terry A. Wheeler2, Charles T. Graham3, and Max A. Batla1. (1) Texas Cooperative Extension, 1102 E. FM 1294, Lubbock, TX 79403, (2) Texas A&M University, 1102 E. FM 1294, Lubbock, TX 79403, (3) Bayer CropScience, P.O Box 1046, Grenada, MS 38901
Cotton (Gossypium hirsutum L.) is a major crop grown throughout the High Plains of Texas. Increased acreage, production north of the traditional growing region, and the presence of adequate soil moisture often play a role in producers gravitating toward earlier planting dates. This change in cultural practice introduces potential production risks. Seedling diseases pathogens, primarily Rhizoctonia solani and Pythium spp., are commonly isolated from cotton fields throughout the region, and occasionally cause significant losses. In 2007, three field trials were conducted to evaluate the performance of various fungicide seed treatments. Seed were planted under conditions that were favorable for disease development. Two trials (A and B) were conducted at the Texas Tech University Quaker Farm, to evaluate various over-treatment fungicides. All plots were artificially infested with R. solani at planting, and treatments were arranged in a randomized complete block design with eight replications per trial. A separate trial (C) was conducted at the Texas A&M University System Halfway Farm to evaluate the efficacy of seed treatments in natural plots and plots artificially infested with R. solani. The experimental design was a split-plot with seed treatment serving as whole-plots, and infestation level serving as sub-plots. Treatments were arranged in randomized design with four replications. Plant stands were enumerated weekly until 49 days after planting (DAP), vigor ratings, and skip indices were taken 28 and 49 DAP, respectively for each trial. Severe seedling disease damage was experienced in trials A and B. All seed treatments significantly increased stand counts and reduced the skip index compared to the untreated seed (negative control). Under inoculated conditions and heavy disease pressure in these trials, neither of the standard seed treatments (positive controls) provided commercially acceptable stands; thus indicating the potential benefits of using additional fungicide over-treatments. Significant differences were observed between treatments and infestation level in Trial C. Final stands ranged from 1.0 to 2.3 and 0.2 to 1.6 plants per foot for plots naturally infested and artificially infested plots, respectively; thus, emphasizing the importance of disease pressure. Yield and fiber quality data will be collected for each plot, and used to determine loan rates. Subsequent analyses will be used to determine the economic benefits of the seed treatments evaluated in this study.
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