Texas cotton producers have long utilized a weed control system to manage weeds in cotton. New technology mandates continuing research to determine effective weed control systems. A total of four studies were established in College Station and Crockett, Texas in 1994 and 1995 to evaluate the technical fit of norflurazon and pyrithiobac combinations for weed control in Texas cotton. The soil types were silty clay loam and loam. Ivyleaf and pitted morningglory, palmer amaranth, smell melon, and Texas panicum were effectively controlled with 1.8 lbs ai/A norflurazon followed by 0.032 and 0.064 lbs ai/A pyrithiobac. Tall morningglory was effectively controlled with 0.6 and 1.2 lbs ai/A norflurazon combined with 1.2 lbs ai/A fluometuron followed by 0.067 lbs ai/A pyrithiobac.

The combination of norflurazon and pyrithiobac improved control of ivyleaf and pitted morninglory over 0.5 and 1X rates of norflurazon. The combination also improved control of smell melon and Texas panicum over the 0.5 and 1 X rates of pyrithiobac on silty clay soil in 1994. The 0.5X rate of norflurazon and pyrithiobac offered similar control to the 1X rate combinations. The 1X rate of norflurazon or pyrithiobac was superior to the 0.5X rate of either herbicide and was equal to the combination of 0.5X plus 0.5X or 1X plus 1X rate combinations for the control of tall morningglory. The 0.5X rate of norflurazon plus 1X fluometuron was superior to 1X trifluralin plus 1X pyrithiobac and equal to 0.25 X norflurazon plus 1X fluometuron plus 1X pyrithiobac for control of tall morningglory and smell melon.