Publication Date


Advisor(s) - Committee Chair

James Worthington, L.D. Brown, W.C. Normand

Degree Program

Department of Agriculture

Degree Type

Master of Science


Investigations were conducted to determine the effects of the herbicide glyphosate and its time of application on the control of johnsongrass.

Johnsongrass plots were divided into areas designated undisturbed, spring plowed, and clipped. These areas were compared to determine differences in control of johnsongrass when using glyphosate with different management procedures. Glyphosate was applied at weekly intervals and treatment effects were statistically analyzed. There were three replications of each treatment.

It appears from the results that:

  1. Glyphosate kills approximately 100% of the johnsongrass topgrowth regardless of the application date.

  2. Height of the johnsongrass plant at the time of glyphosate application had little influence on the ability of the herbicide to kill the rhizomes.

  3. Rhizomes from plants that had received an application of glyphosate produced a significantly lower number of plants than did rhizomes from untreated plants.

  4. The management procedures (spring plowed, clipped, undisturbed) had no effect on the ability of glyphosate to kill the rhizomes.

  5. As glyphosate applications were applied later in the growing season, johnsongrass control increased.

  6. In 1975 glyphosate utilized with spring plowing produced better total johnsongrass control than either clipped or undisturbed plots which had utilized glyphosate. In 1976 there was no significant difference in the control given by the three methods.


Agriculture | Life Sciences | Plant Sciences | Weed Science