Influence of Fenoxaprop and Ethofumesate Treatments on Suppression of Common Bermudagrass (Cynodon dactylon) in Tall Fescue (Festuca arundinacea) Turf

Abstract

Experiments were conducted over a 3-yr period to determine the rate and frequency of herbicide application needed to control common bermudagrass growing in a tall fescue turf. In Experiment I, fenoxaprop plus ethofumesate applied at 0.2 + 1.7 kg/ha in late April and repeated at the same rate at 3- to 4-wk intervals for a total of five applications resulted in excellent (≥ 97%) common bermudagrass suppression. The suppression was higher from combination of fenoxaprop and ethofumesate than when fenoxaprop was applied at 0.2 kg/ha in five applications (≤ 67%). In Experiment II, fenoxaprop plus ethofumesate applied at 0.2 +1.7 kg/ha required four applications per year to effectively suppress common bermudagrass (95%) in 1993, but five applications were needed to obtain similar suppression (96%) in 1994. Tifway bermudagrass was not suppressed during 1994 when fenoxaprop plus ethofumesate were applied at 0.2 +1.7 kg/ha in each of five applications (30%). In most instances, fenoxaprop plus ethofumesate applied at 0.2 +1.7 kg/ha caused only slight to moderate (< 30%) injury to tall fescue for 1 to 2 wk after treatment. When injury occurred, it was temporary as the turf fully recovered within 2 to 3 wk after treatment. An exception occurred in early July 1992 when fenoxaprop plus ethofumesate caused 44% injury to tall fescue after the four applications.