Using the critical period for weed control to manage weeds in Roundup Ready Flex cotton in the 2007-08 season

Abstract

Data from last season was used to test the critical period for weed control approach for irrigated and dryland Roundup Ready Flex cotton crops. The critical period for weed control was applied to dirty, average and clean fields, where weeds emerged after each rainfall and irrigation event. Applying the critical period approach required that the start of weed control began soon after crop emergence, while weeds were still small. A lighter herbicide rate might be appropriate for small weeds. The duration of the critical period depended on the density of weeds that emerged after the first treatment. All weed flushes in the 2007-08 season were controlled using Roundup during the critical period, with an inter-row cultivation or an early application of a residual layby herbicide available as an additional weed management tool if required. The results show that ensuring weeds are controlled soon after emergence is a practical approach to weed control which will help optimize crop yields. The approach can be equally applied to irrigated and dryland crops using Roundup Ready Flex, Liberty Link or conventional cotton varietie