Jim Klauzer

Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Plant Science

First Advisor

W. Eugene Arnold


Annual grasses and broadleaf weeds reduce soybean yields. Preplant and preemergence herbicide applications control these weeds in production systems which utilize the moldboard plow but are less effective in conservation tillage systems. Preplant herbicides provide less effective weed control in “reduced tillage” practices because incorporation is not accomplished. Preemergence herbicides are less effective in conservation tillage systems because the heavy crop residue does not allow contact of the chemical with the seed bed. The poor coverage with preemergence herbicides allows many weeds to escape control. Untimely weather conditions prevent proper application of preemergence herbicides in both conventional and conservation tillage systems. Therefore, soybean growers are relying on postemergence herbicide applications to control summer annual weeds. The judicious use of herbicides is an additional factor when considering the use of a postemergence chemical. The use of postemergence herbicide allows a grower to selectively treat problem areas in his fields. The reduced usage of chemical is not entirely feasible with either preplant or preemergence herbicides. Treatment of entire fields may be necessary as weeds are not visible at the time of application. The objectives of this research were to: (1) determine if tank-mix combinations of diclofop-methyl, difenopenten, or sethoxydim, each with bentazon are antagonistic for control of either annual grasses or broadleaf weeds and if these combinations are safe when used on soybeans. (2) evaluate the influence of the growth stage of annual grasses at herbicide application on weed control using diclofop-methyl, difenopenten and sethyoxydim. (3) determine if different water carrier volumes influence the performance of postemergence herbicides on control of the annual grasses.

Library of Congress Subject Headings

Soybean -- Weed control.
Grasses -- Control.
Weeds -- Control.



Number of Pages



South Dakota State University


No Copyright - United State