Replicated large scale commercial size plots were established at seven locations in Arkansas and West Tennessee to evaluate the effects of Roundup Ultra ^® herbicide on Roundup Ready ^® cotton varieties. The objectives of these studies were to compare fruiting characteristics, yield, and weed management costs of three weed management systems: 1. Conventional herbicide program (CON), 2. Roundup Ultra overtop prior to the four leaf stage followed by conventional herbicides post directed (RUP fb CON) and 3. Roundup Ultra overtop prior to the four leaf stage followed by Roundup Ultra post directed (RUP fb RUP). Fewer first position harvestable bolls and greater first position abnormal bolls were detected at sympodia 8 for the RUP fb RUP system, however, consistent treatment differences failed to develop on subsequent fruiting positions. Compensation occurred on both first and second positions above sympodia
8. The average herbicide costs for the conventional system were $10.34 and $9.52 per acre greater than the RUP fb CON and the RUP fb RUP, respectively. The RUP fb RUP system yielded 121.1 and 54.5 pounds more lint per acre than the CON and RUP fb CON systems, respectively. Reduced input costs and greater yields in the RUP fb RUP systems resulted in higher net returns of $23.99 and 75.71 per acre more than the RUP fb CON and CON systems, respectively.