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.

Detection of grassy weeds in bermudagrass with deep convolutional neural networks

“…The use of MSMA is banned in turfgrass systems in Florida, while in other states only a single broadcast application is permitted for newly constructed golf courses and spot application is permitted for other golf courses (MSMA 6 Plus Label, Drexel, Memphis, TN). The current herbicide program for control of P. dilatatum and U. distachya is neither efficient nor cost-effective (Cross et al 2016;Henry et al 2007;Pearsaul et al 2018). For example, repeat applications of amicarbazone at 0.25 kg ai ha −1 in combination with sulfonylurea herbicides, including thiencarbazone þ foramsulfuron þ halosulfuron, provided adequate control of U. distachya (Cross et al 2016;Pearsaul et al 2018).…”

“…The current herbicide program for control of P. dilatatum and U. distachya is neither efficient nor cost-effective (Cross et al 2016;Henry et al 2007;Pearsaul et al 2018). For example, repeat applications of amicarbazone at 0.25 kg ai ha −1 in combination with sulfonylurea herbicides, including thiencarbazone þ foramsulfuron þ halosulfuron, provided adequate control of U. distachya (Cross et al 2016;Pearsaul et al 2018). However, amicarbazone is quite expensive, and a single broadcast application at a rate of 0.25 kg ai ha −1 costs approximately US$1500.…”

Evaluation of Verticutting and Herbicides for Tropical Signalgrass (Urochloa subquadripara) Control in Turf

“…The combination of AMI+MESO+TSS includes three different modes of action, two of which (PSII and HPPD inhibitors) have been shown to produce synergistic responses in certain situations, primarily against broadleaf weeds (Abendroth et al 2006; Hugie et al 2008). The other mode of action, ALS inhibition, has been shown to increase efficacy when tank mixed with AMI (Cross et al 2016).…”

“…PSII inhibitors, such as AMI, have shown synergistic responses when combined with HPPD inhibitors (Abendroth et al 2006) and complementary responses when combined with ALS-inhibiting herbicides (Cross et al 2016). In this study, AMI displayed potential synergistic responses for TSG control when combined with HPPD or ALS inhibitors.…”

“…There is a need to further explore the role that cultural practices can play as part of an integrated management program. Recent research has shown acceptable levels of TSG control using POST herbicides such as AMI and TFH (Cross et al 2016; McCarty and Estes 2014). However, as was the case with MSMA, if a chemical is banned or becomes ineffective, turfgrass managers are left without any effective tools at their disposal.…”