Publication Date

12-1982

Advisor(s) - Committee Chair

James Worthington, Alvin Bedel, Ray Johnson

Degree Program

Department of Agriculture

Degree Type

Master of Science

Abstract

Johnsongrass (Sorghum halepense) is one of the most troublesome weeds in the southeastern United States. -everal herbicides have been developed to combat johnsongrass, and many new experimental herbicides with high johnsongrass control potential are presently being tested. Two of these new experimental herbicides for johnsongrass control in soybeans (Glycine max) are sethoxydim and MBR 22359.

Field experiments were conducted in 1981 and 1982 to evaluate the effectiveness of MBR 22359 preemergence and postemergence, sethoxydim in single and split applications, trifluralin in combination with mefluidide, or with glyphosate or sethoxydim in the wick, and alachior in combination with glyphosate or sethoxydim in the wick for rhizome johnsongrass control in soybeans. In 1982 fluchioraiin was also tested for rhizome johnsongrass control in soybeans.

In both years MBR 22359 was applied at 2.2, 3.4, and 4.5 kg/ha preemergence, and at 1.1 and 2.2 kg/ha postemergence. In 1981 sethoxydim was applied in single applications at 0.3, 0.4, and 0.7 kg/ha early postemergence, 0.7 kg/ha late postemergence, and in split applications early postemergence and late postemergence respectively at 0.2 plus 0.2, 0.3 plus O.', 0.4 plus 0.4, and 0.4 plus 0.2 kg/ha. In 1982 sethoxydim was applied in single applications at 0.2, 0.3, 0.4, and 0.6 kg/ha early postemergence, and in split applications early postemergence and late postemergence respectively at 0.2 plus 0.1, 0.2 plus 0.2, 0.3 plus 0.1, 0.3 plus 0.2, and 0.4 plus 0.2 kg/ha. In 1981 and 1982 trifluralin at 1.1 kg/ha was applied in combination with mefluidide at 0.3 kg/ha early postemergence, mefluidide at 0.3 kg/ha early postemergence plus mefluidide at 0.3 kg/ha late postemergence, mefluidide at 0.3 kg/ha early postemergence in combination with glyphosate plus water (1:2, v/v) directed postemergence, sethoxydim plus oil plus water (2:1:3, v/v) directed postemergence, or with glyphosate plus water (1:2, v/v) directed postemergence in the rope wick applicator. Alachlor was applied at 3.4 kg/ha in combination with sethoxydim plus oil plus water (2:1:3, v/v) or with glyphosate plus water (1:2, v/v) directed postemergence in the rope wick applicator. In 1982 fluchloralin was applied at the rate of 2.2 kg/ha.

Sethoxydim single and split application treatments at all rates employed excellent rhizome johnsongrass control in 1981 and 1982. No soybean injury was noted and good yields were obtained where sethoxydim was applied.

MBR 22359 preemergence treatments provided good to excellent rhizome johnsongrass control. soybean injury and yield reductions were noted with the MBR 22359 postemergence and the 4.5 kg/ha preemergence treatments in 1981. No significant differences in yields were found between any of the herbicide treatments in 1982.

Trifluralin combinations and alachlor combinations provided poor to fair rhizome johnsongrass control in both years. Soybean injury was noted for the trifluralin combination treatments that contained mefluidide. Yields were generally not as high for the trifluralin combinations and alachlor combinations as they were for the sethoxydim, and the lower rate MBR 22359 preemergence treatments in 1981. Fluchloralin provided extremely poor rhizome johnsongrass control in 1982.

Disciplines

Agriculture | Weed Science

Download

Share

COinS