Chemistry and Fate of Triazolopyrimidine Sulfonamide Herbicides

Abstract

The triazolopyrimidine sulfonamide (TSA) herbicides were registered in the United States in 1993. Their mode of action is by inhibition of acetolactate synthase (ALS), an enzyme common to plants and microorganisms but not found in animals. ALS inhibitors include other herbicide families such as the sulfonylureas, imidazolinones, and pyrimidinyl thiobenzoates. In the 1970s, sulfonylureas were the first ALS inhibitors to be introduced to the market. Their discovery was greeted as a great achievement because of their ability to suppress weeds at extremely low application rates compared to previously used herbicides and with low toxicity risk to humans and wildlife. By 1991, the market value of ALS inhibitors had reached $1.3 billion (U.S.). However, some of the problems associated with their use include the induction of resistance in weed species to both ALS-inhibiting and alternative herbicides. ALS inhibitors have also been found to damage nontarget plants at residual levels that are below the detection limits of standard analytical methods (Saari et al. 1994; Whitcomb 1999).

Effect of Environmental Conditions on the Degradation of Florasulam in Typical Soils of Northern China

“…Ma and Li (2016) reported that florasulam showed comparatively high mobility and leaching degree and noted that it presented a high risk of polluting groundwater. Jabusch and Tjeerdema (2008) reported that florasulam has a polar nature and fairly high water solubility and is a potential water pollutant that presents environmental risks for aquatic plants and microorganisms. Other studies on florasulam have concentrated on its adsorption and dissipation.…”

“…), wild buckwheat ( Polygonum convolvulus L.), and many Cruciferae at very low application rates (Daniau and Prove, 2001; Deboer et al, 2006; Jackson et al, 2000). By the end of 2016, 86 products that contained florasulam were registered in China, and its usage has increased annually (Jabusch and Tjeerdema, 2008; Mukherjee et al, 2016; Zhao et al, 2015; Pesticide Assistant Database [http://www.ny188.cn/Index.html]).…”

Integrated Transcriptomic and Metabolomic Analyses of the Molecular Mechanisms of Two Highland Barley Genotypes with Differential Pyroxsulam Responses

“…Pyroxsulam is a new triazolopyrimidine sulfonamide acetolactate synthase (ALS)-inhibiting herbicide developed by Dow AgroSciences (Indianapolis, IN), which provides broad-spectrum control of many annual, biannual and perennial weeds. It has the advantage of high e cacy with low doses and a favorable environmental pro le [7]. Pyroxsulam acts by inhibiting ALS, an important target for herbicides, which is an essential enzyme that catalyzes the rst step in the synthesis of the branched-chain amino acids valine, leucine and isoleucine [8].…”

Batch Leaching Studies of Penoxsulam Herbicide in Two Different Soils

“…Penoxsulam is highly mobile but not very persistent in both water and soil [7]. Its dissipation in water could be the after effect of photolysis [8].…”