Establishment of Forage Grasses and Legumes After Fall Herbicide Applications

Research was conducted at two sites to measure the establishment and productivity of forage grasses and legumes in the spring and summer following a fall herbicide application. Establishment of orchardgrass and Italian ryegrass was reduced with metsulfuron at 0.042 kg ai/ha and imazapic at 0.21 kg ae/ha at one site, while aminopyralid at 0.087 to 0.122 kg ae/ha, metsulfuron, and imazapic reduced establishment of red clover, alfalfa, and white clover the following spring, 7 months after treatment. Delaying planting of legumes 11 months after treatment improved establishment of most treatments as reductions were documented only with clopyralid and aminopyralid treatments at one site. Forage productivity of grasses was not affected except with Italian ryegrass; however, spring planted red clover, alfalfa, and white clover biomass was reduced by > 86% with metsulfuron treatments compared to untreated plots. Reductions in yields of forage legumes from metsulfuron did not occur in late summer plantings. Results indicate that spring planting after fall herbicide application can result in reductions in establishment and productivity depending on the herbicide and forage species utilized.