Establishment of one plant per square yard is considered an acceptable stand since individual plant crowns can be 4 feet in diameter. Annual grasses can cause problems in the establishment year. Establishment is the most critical period for weed control. Few herbicides are labeled for eastern gamagrass, although several are in development. See MU publication MP581, Weed and Brush Control Guide for Forages, Pastures and Non-Cropland, for the most current information on herbicides.
Several options exist for weed control during establishment.
Eastern gamagrass can be seeded into fields that have been planted to corn or sorghum for several years prior to seeding where atrazine was used to control weeds in these crops. If atrazine was used at maximum rates for the previous crops, carry-over should be adequate to provide weed control for eastern gamagrass during establishment. Another option is to use a thin seeding of grain sorghum or a sorghum-Sudan grass hybrid as a nurse crop and apply atrazine at 1 pound per acre to the nurse crop. This can be accomplished by seeding the nurse crop in alternate rows with the eastern gamagrass or seeding the nurse crop in one direction and then the eastern gamagrass in rows perpendicular to the nurse crop. The nurse crop can be harvested for hay when it is in the boot stage.