Publication Date

12-1981

Advisor(s) - Committee Chair

James Worthington, W.O. Normand, Ray Johnson

Degree Program

Department of Agriculture

Degree Type

Master of Science

Abstract

Johnsongrass is one of the more limiting factors in soybean production and is the most serious weed problem in the Southeastern United States. Actually, different herbicides are used in johnsongrass control, and still there are new herbicides which are being tested. Two experimental herbicides for johnsongrass control in soybeans are BAS 9052 and S-734.

The experiments were conducted in 1980 and 1981 with the objective to evaluate the effectiveness of S-734 alone and in combination with mefluidide and BAS 9052, BAS 9052 applied early or late postemergence, trifluralin, alachlor, and fluchloralin for seedling and rhizome johnsongrass control.

In both areas S-734 was applied at 0.8, 1.1, and 1.7 kg/ha, S-734 at rates of 0.8, 1.1, and 1.7 kg/ha was combined with mefluidide at 0.3 kg/ha, S-734 at rates of 1.1 and 1.7 kg/ha was also combined with BAS 9052 at 0.6 kg/ha, BAS 9052 was applied at 0.6, 0.8, and 1.1 kg/ha early or late postemergence. Trifluralin and fluchloralin were applied at rate of 1.1 kg/ha in seedling study and 2.2 kg/ha in rhizome study. Alachlor was applied at rates of 3.4 and 4.5 kg/ha in seedling study.

The results of the experiments showed that there were similarities and differences in the response of rhizome and seedling johnsongrass to the treatments. The control of johnsongrass, and the resulting soybean yields, was higher in the seedling area than in the rhizome area. There were no differences among rates of herbicides.

Good seedling johnsongrass control was obtained with all treatments although there were differences among herbicides. In 1980 there were differences between BAS 9052 applied early and late postemergence, but there were no differences in 1981. BAS 9052 might be used as a late postemergence application for best seedling johnsongrass control. There were no differences among herbicides on soybean yields.

In both years good rhizome johnsongrass control was obtained with BAS 9052 applied early or late postemergence. Poor rhizome johnsongrass control was obtained with S-734, trifluralin, and fluchloralin. High soybean yields were obtained with BAS 9052.

Disciplines

Agricultural Science | Agriculture | Agronomy and Crop Sciences | Life Sciences | Plant Sciences | Weed Science

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