Evaluating Time of Day Effects on Broadleaf Weed Control in Xtendflex Cotton

The purpose of this study was to quantify the effect that time of day has on the efficacy of herbicide application. For this study, XtendFlex® cotton was planted and over-seeded with three common and troublesome weed species; morningglory spp., sicklepod, and prickly sida. Treatments of glyphosate, dicamba, and a tank-mix of the two were applied at eight times in a 24hr period. The times varied throughout the day and night based on common times that a grower might be applying herbicides. A randomized complete block design was utilized across two locations in southern Georgia over two years, and visual ratings of weed control were taken at 7, 14, 21, and 28 days after treatment. Data was then analyzed and showed significant differences between several of the timings of treatment.