Postemergence Tropical Signalgrass (Urochloa subquadripara) Control with Nonorganic Arsenical Herbicides

Abstract

Tropical signalgrass (TSG) has become a serious weed problem in tropical and subtropical regions such as Florida in recent years in association with the ban of organic arsenical herbicide use in turf. The purpose of this research was to identify alternative POST herbicides that control TSG. Two field experiments were conducted in bermudagrass golf course fairways in south and central Florida in 2014 and 2015. Several nonorganic arsenical herbicide treatments controlled TSG. In the first experiment, treatments containing amicarbazone alone and in combination with other herbicides provided > 97% TSG control 12 wk after initial treatment (WAIT) in 2014 and 2015. These included a single application of amicarbazone at 0.49 kg ai ha−1, or sequential applications of amicarbazone at 0.25 kg ha−1in combination with foramsulfuron at 0.04 kg ai ha−1, sulfentrazone + imazethapyr at 0.25 kg ai ha−1, thiencarbazone + foramsulfuron + halosulfuron at 0.14 kg ai ha−1, and thiencarbazone + iodosulfuron + dicamba at 0.18 kg ai/ae ha−1. In the second experiment, sequential applications of thiencarbazone + foramsulfuron + halosulfuron at 0.14 kg ha−1in combination with either quinclorac at 0.84 kg ai ha−1or metribuzin at 0.28 kg ai ha−1provided ≥ 85% TSG control 12 WAIT in both years.