INTRODUCTION TO THE SYMPOSIUM: HISTORY OF SULFONYLUREA HERBICIDES IN TURFGRASS ENVIRONMENTS. P. C. Bhowmik*; University of Massachusetts, Amherst, MA (165)
Weed management is a science-based decision-making process that includes the knowledge of weed biology, environmental information, and available technology to maintain qualities of turfgrass species. This type of approach may lead to least possible risks to people and the environment. Although sulfonylurea (SU) herbicides were initially introduced in the agricultural market in 1982, the researchers evaluated SUs for control of weedy and overseeded grasses. Later, SUs were evaluated for selective control of broadleaf weeds, sedges, and kyllinga species in both cool-season and warm-season turfgrasses. Herbicidal activity of SUs is characterized by high biological activity on susceptible weeds, short half-lives and low toxicities to animal species. SUs act by inhibiting the plant-specific ALS enzyme, which is required for the biosynthesis of branched-chain amino acids (valine, leucine and isoleucine) required components of the growth processes of cell division at the root and shoot tips. In 1990’s, chlorsulfuron and metsulfuron were introduced into the turfgrass market for selective control of broadleaf weeds and difficult-to-control grasses, including wild garlic (Allium vineale), prostrate spurge (Euphorbia maculata) and bahiagrass (Paspalum notatum). In 2000’s, halosulfuron, rimsulfuron, flazasulfuron, sulfometuron, sulfosulfuron, foramsulfuron and trifloxysulfuron were introduced for controlling problematic weeds like annual bluegrass (Poa annua), clumpy ryegrass (Lolium perenne), creeping bentgrass (Agrostis palustris), and sedges like yellow nutsedge (Cyperus esculentus), purple nutsedge (Cyprus rotundus), green kyllinga (Kyllinga brevifolia) and false green kyllinga (Kyllinga gracillima). In this symposium, speakers will examine the current status of SUs and identify potential benefits and drawbacks in using these herbicides for weed management practices. Speakers will discuss their research findings, vision, and possible recommendations in relation to the safety of turfgrass (established and overseeding stands), environmental concerns (persistence and lateral movement) and potential evolution of weed resistance. Successful cases of weed management practices in both cool-season and warm-season turfgrass systems will be highlighted.