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Recorded Presentations
Michael A. Jones, Clemson University, Pee Dee Research and Education Center, 2200 Pocket Rd., Florence, SC 29506
Cotton is produced in the Coastal Plain of South Carolina in fields that have tremendous amounts of within field soil variability. This soil variability usually results in the development of cotton plants with a tremendous amount of growth variability associated with them. This within field growth variability makes the management of cotton in these fields extremely difficult. Growers usually have to make a compromise in their management by either applying inputs at moderate rates based on the average of all the plants in an individual field or by applying higher rates across the entire field based on the yield potential of a small area of the field. Both of these methods results in wasted inputs, reduced efficacy of the products applied, reduced lint quantity/quality, and reduced profits. Recent advances in precision agriculture technology has now made available equipment that allows growers to better manage their inputs by addressing field variability and minimizing management input waste. Utilizing variable rate application equipment and crop canopy sensors which take plant measurements as equipment moves across the field, growers can now potentially increase their profits by applying the appropriate amount of inputs to the appropriate plants "on the go" in variable fields (site-specific applications). One such system measures real time canopy reflectance or a vegetative growth indice (NDVI) and allows growers to apply solid and liquid inputs at variable rates on the go. These NDVI systems can be mounted on sprayers, tractors, and/or be used by consultants or growers by hand.With the soaring prices of fuel, nitrogen, and crop protection chemicals and stagnant yields and prices associated with cotton production, growers desperately need research that will help them reduce their input costs and potentially increase their profit margin. Most research on variable rate applications based on crop canopy reflectance or NDVI has been associated with sidedress nitrogen applications. Two other cotton management inputs that has the potential to benefit from precision applications are plant growth regulator applications and harvest aid applications. It is often said by researchers, consultants, and growers that the proper application of plant growth regulators and harvest aid materials is more ART than SCIENCE. This is because the proper choice and rates of these products needs to be based on the current growth conditions of plants when the products are applied. Failures of plant growth regulators and harvest aids to give growers the desired results in most cases is associated with the high amount of crop variability within fields in South Carolina and the improper use or rate of products for the crop condition present. Currently, little research exists on the potential use of crop vegetation indices (NDVI measurements) as a tool to use variable rate applications of PGRs and harvest aids in cotton. An initial research trial conducted this past growing season in cooperation with Dr. Phil Bauer (USDA-ARS) showed promising results for this technology. We found a positive correlation between NDVI measurements and application rates of DEF/Folex defoliant. PGR Trial. A replicated plant growth regulator trial was conducted in a field at the Pee Dee REC located in Florence, SC with a high amount of soil variability. Five plant growth regulators (Pentia, GinOut, PixPlus, and generic Mepiquat Chloride) were applied at four rates (0, 8, 16, and 32 oz/Acre) at early bloom. Stance was applied at 1.5, 3, and 6 oz/acre. Before each application, NDVI measurements were taken at five locations in each plot. Plant height, number of nodes, and leaf area measurements were taken from the area where the NDVI measurements were taken. Boll counts and lint yield were also taken from these areas of each plot at season’s end. Data was analyzed using correlation and regression analysis. A replicated plant growth regulator trial was conducted in a field at the Pee Dee REC located in Florence, SC with a high amount of soil variability. Five plant growth regulators (Pentia, GinOut, PixPlus, and generic Mepiquat Chloride) were applied at four rates (0, 8, 16, and 32 oz/Acre) at early bloom. Stance was applied at 1.5, 3, and 6 oz/acre. Before each application, NDVI measurements were taken at five locations in each plot. Plant height, number of nodes, and leaf area measurements were taken from the area where the NDVI measurements were taken. Boll counts and lint yield were also taken from these areas of each plot at season’s end. Data was analyzed using correlation and regression analysis. Harvest Aid Trial. A replicated harvest aid trial was also conducted. Six harvest aid materials were applied at 5 different rates (0, 1/2x rate, 1x rate, 2x rate, and 4x rate) at the 50% open boll stage. Def/Folex was applied at 0, 4, 8, 16, and 32 oz/acre. Finish 6 Pro was applied at 0, 0.67, 1.33, 2.67, and 5.34 pt/acre. Ginstar was applied at 0, 0.25, 0.5, 1.0, and 2.0 pt/acre. Dropp 50WP was applied at 0, 0.1, 0.2, 0.4, and 0.8 lb/acre. Harvade was applied at 0, 4, 8, 16, and 32 oz/acre. Aim was applied at 0, 0.33, 0.67, 1.33, and 2.67 oz/acre. Before each application, NDVI measurements were tan at five locations in each plot. Leaf area measurements, visual defoliation ratings, dessication ratings were taken from the area where the NDVI measurements were taken at 0, 7, and 14 days after the initial treatments were applied. Data was analyzed using correlation and regression analysis. A replicated harvest aid trial was also conducted. Six harvest aid materials were applied at 5 different rates (0, 1/2x rate, 1x rate, 2x rate, and 4x rate) at the 50% open boll stage. Def/Folex was applied at 0, 4, 8, 16, and 32 oz/acre. Finish 6 Pro was applied at 0, 0.67, 1.33, 2.67, and 5.34 pt/acre. Ginstar was applied at 0, 0.25, 0.5, 1.0, and 2.0 pt/acre. Dropp 50WP was applied at 0, 0.1, 0.2, 0.4, and 0.8 lb/acre. Harvade was applied at 0, 4, 8, 16, and 32 oz/acre. Aim was applied at 0, 0.33, 0.67, 1.33, and 2.67 oz/acre. Before each application, NDVI measurements were tan at five locations in each plot. Leaf area measurements, visual defoliation ratings, dessication ratings were taken from the area where the NDVI measurements were taken at 0, 7, and 14 days after the initial treatments were applied. Data was analyzed using correlation and regression analysis.
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