Influence of location, soil types, and herbicide rates of cotton response to fluometron and trifluralin

Weed control in cotton is achieved by using a system of mechanical cultivation and herbicide application. Over the past few years the yield per hectare of cotton has decreased throughout Tennessee. Field studies were conducted during 1977 at Ames Plantation, Jackson, and Milan to determine if the decrease in production has been due to the phytotoxic effects of herbicides currently in use.

The plots were arranged in a split-plot design with four replications at Jackson and three replications at Ames and Milan. The main treatments were trifluralin at 0 and 0.8 kg/ha applied preplant incorporated. The sub-plot treatments were fluometuron at 0, 0.8, 1.1, 1.4, 1.7, and 3.4 kg/ha applied preemergence. All plots were maintained in a weed-free condition by hand-hoeing and mechanical cultivation. Soil types were: Loring silt loam and Memphis silt loam at Ames Plantation; Grenada silt loam, Loring silt loam, and Falaya silt loam at Milan; and Memphis silt loam at Jackson. Data were obtained on cotton seedling fresh and dry weight, stand, maturity date, and yield.

Early herbicide injury, as noted by fresh and dry weight, was later expressed in delayed cotton maturity. A significant reduction in yield occurred on the Memphis silt loam at Ames and Jackson on plots treated with 3.4 kg/ha (2X) rate of fluometuron without trifluralin. Also, yield was reduced by the 3.4 kg/ha (2X) rate of fluometuron both with and without trifluralin on the Loring silt loam at Ames. No significant yield differences were observed at Milan.

Even though some early injury and delay in maturity were noted at some locations, the data from this one-year experiment showed no reduction in cotton yields when recommended rates of the herbicides were used.