Evaluation of Smutgrass Control Using the Weed Wiper Approach.

Smutgrass Control Using the Weed Wiper Approach

Rocky Lemus, Mark Mowdy, and Ann Davis

Smutgrass (Sporobolus indicus L.) is a very invasive bunchgrass causing serious weed problems in perennial grass pastures and roadsides in Mississippi.  Many ranches in southern Mississippi are heavily infested with this invasive weed; it has begun to proliferate in the central and northern areas of the state as well.  Some of the control practices have included chemical control and cultural practices such as mowing, burning, or renovation of heavily infested areas.  Research has shown that mowing or burning does not control smutgrass, but instead promotes the spread and germination of seed. Pasture renovation can be expensive and gives variable results due to smutgrass re-establishment from the soil seed bank.  Most of the pastures in the southern region of Mississippi are mainly bahiagrass (Paspalum notatum), making smutgrass control with hexazinone more difficult because of its detrimental effect on bahiagrass.  The uptake mode of hexazinone is through the roots of the plant, requiring spot treatment to obtain an effective control. Although some grazing occurs on mature smutgrass, most of it is usually unpalatable to livestock.  The objective of the study was to determine the effect of hexazinone and glyphosate on smutgrass control using the weed wiper approach.  A control demonstration was established in Centreville, Mississippi on a bahiagrass pasture heavily infested with smutgrass.  Plots were 4.25 m x 7.6 m.  The weed wiper (WeedWorks) was used to apply VelparŪ at a rate of 4.67 L ha^-1 and glyphosate at two different rates (33% and 50% solution).  Glyphosate application was done using two methods in the pasture: 1) application in a single direction in the plot (1X) or 2) applying glyphosate in both directions in the plot (2X).   Applications were made on June 17, 2009 and pictures were taken throughout the rest of the growing season to monitor control and smutgrass recovery.  Ten specific smutgrass plants were marked with wooden sticks and monitored for recovery the following spring.