Newly Established Bermudagrass Response to Topramezone and Photosystem II-Inhibitor Herbicides

Abstract

Bermudagrass is the most troublesome and difficult-to-control perennial grass weed in Florida sugarcane. Once established, it is only controlled effectively during the sugarcane fallow period using nonselective herbicides and tillage combinations. It is important to evaluate options for selective management of bermudagrass that escape sugarcane fallow period management programs to mitigate its progressive increase as the crop cycle increases from plant cane to ratoon crops. Greenhouse and field studies were conducted in Belle Glade, Florida, from 2017 to 2018 to determine the response of newly established bermudagrass from sprigs with stolons to two or three sequential applications of topramezone (25 and 50 g ha^-1) every 14 d and the combinations of topramezone (25 and 50 g ha^-1 ) with photosystem II (PS II)-inhibitor herbicides atrazine (2,240 g ha^-1), ametryn (440 g ha^-1), and metribuzin (2,240 g ha^-1). Two or three sequential applications of topramezone with a cumulative total of 75 to 100 g ha^-1 provided >93% bermudagrass control 42 d after the first sequential application under greenhouse and field conditions. These treatments had 12% chance of survival 70 d after the first sequential application. There was an additive effect of PS-II inhibitor herbicides on bermudagrass control in mixtures with topramezone. The mixture of topramezone (50 g ha^-1) with metribuzin and atrazine provided more than 87% and 92% bermudagrass control under greenhouse and field conditions, respectively, 42 d after treatment. Bermudagrass treated with topramezone (50 g ha^-1) mixture with metribuzin had 23% chance of survival 70 d after treatment. The results show good efficacy of sequential topramezone applications every 14 d or mixtures with PS-II inhibitor herbicides atrazine and metribuzin for control of newly established bermudagrass which typically escape control measures during the sugarcane fallow management period.