Sequential Herbicide Treatments for Goosegrass (Eleusine indica) Control in Bermudagrass (Cynodon dactylon) Turf1

Goosegrass control studies were conducted with multiple preemergence (PRE) and postemergence (POST) herbicides on bermudagrass fairways on the tropical island of Guam. Two POST applications of MSMA plus metribuzin, applied 1 wk apart were needed to control the existing goosegrass. Three applications of these herbicides showed a clear trend in goosegrass control, with control lasting 4 wk longer than two treatments. PRE herbicides provided efficacious control only when applied in sequence with a single MSMA plus metribuzin application. The control from sequential applications of PRE herbicides was generally no better than that with two applications of MSMA plus metribuzin. However, application of MSMA plus metribuzin resulted in turf discoloration lasting 5 to 8 wk. A single POST application reduced turf quality from 35 to 41% when compared to the untreated check. Two applications caused an additional 5 to 7% reduction in turf quality. Three applications caused similar discoloration as two applications. Application of PRE herbicides had no effect on turf quality, with ratings being equal to those of plots treated with POST herbicides only.Nomenclature: MSMA; metribuzin; bermudagrass, Cynodon dactylon (L.) Pers. #3 CYNDA; goosegrass, Eleusine indica (L.) Gaertn. # ELEIN.Abbreviations: POST, postemergence; PRE, preemergence.