ABSTRACT

Increased canopy shading of the soil with narrow row cotton may permit producers to use reduced levels of herbicide while maintaining adequate levels of weed control for profitable cotton production. Cotton planted in 30 and 40 inch rows was evaluated for weed control and lint production with reduced herbicide rates. Preemergence treatments of pendimethalin applied at 0.5, 1.0, and 1.5 lb a.i./acre; trifluralin at 0.25, 0.50, and 0.75 lb a.i./acre; a handweeded control; and a weedy check were included in the experiment in the lower Rio Grande Valley. Measurements taken were cotton plant height, node number, control of Panicum texanum (PANTE), and Amaranthus palmeri (AMAPA), percent canopy coverage, and lint yield at 121, 134, and 146 days after emergence (DAE) of cotton. Crop canopy closure occurred approximately 14 days earlier in 30 inch rows than in 40 inch rows. 30 inch rows had a greater percentage of cotton which was mature by the second harvest (134 DAE) than the 40 inch row treatments. Trifluralin treatments at 0.25 lb/A and the weedy check had a statistically lower overall lint yield in 30 inch rows than in 40 inch rows. Within similar row spacings, cotton treated with reduced rates of herbicide had lint yields similar to those treated with full rates of the same herbicide.