But just six feet away, pigweed that was sprayed in the cooler morning was almost totally killed. Staple is important in the Cotton Belt because it is the only herbicide that farmers can spray over the top of cotton plants without harming cotton.
Staple works by inhibiting a key plant enzyme.
Two years of field studies confirmed the lab results. Mahan and Dotray recommend that farmers check the five-day forecast before they spray Staple, to see which will be the coolest days. Farmers might consider stopping the application before the day gets too warm. The temperature at spraying time has the greatest effect on how well Staple works, even though it takes the compound two weeks to kill weeds. The experiment grew out of Mahan's discovery that key plant enzymes did best within a narrow temperature range, causing plants to grow best at those temperatures.