Tolpyralate + Atrazine Applied Preemergence Provides Residual GR Canada Fleabane [<i>Conyza canadensis</i> (L.) Cronq.] Control Similar to Current Industry Standards

Abstract

Tolpyralate is a benzoylpyrazole, 4-hydroxyphenyl-pyruvate dioxygenase inhibitor, and a herbicide registered for use in corn. The efficacy of tolpyralate plus atrazine to provide full-season residual control of glyphosate-resistant (GR) Canada fleabane in corn is not known under Ontario environmental conditions. Five field trials were completed over a two-year period (2018-19) in southwestern Ontario on farms with confirmed GR Canada fleabane [Conyza canadensis (L.) Cronq.] populations to determine if tolpyralate + atrazine provides full-season residual control of GR Canada fleabane in corn. Corn injury was less than 10% with all treatments. At 4 weeks after application (WAA), tolpyralate (30 g•ai•ha −1), tolpyralate (40 g•ai•ha −1), and atrazine (560 g•ai•ha −1) controlled GR Canada fleabane 64, 78 and 72%, respectively. A tank mix of tolpyralate + atrazine at both rates improved GR Canada fleabane control to 94%. Saflufenacil/dimethenamid-p, mesotrione + atrazine, and dicamba/atrazine controlled GR Canada fleabane 99, 95 and 92%, respectively. At 8 WAA, tolpyralate (30 g•ai•ha −1), tolpyralate (40 g•ai•ha −1) and atrazine (560 g•ai•ha −1) controlled GR Canada fleabane 83, 88, and 83%, respectively (Table 2). The tank mixes of tolpyralate (30 g•ai•ha −1) + atrazine (560 g•ai•ha −1) and tolpyralate (40 g•ai•ha −1) + atrazine (560 g•ai•ha −1) controlled GR Canada fleabane 94, and 97%, respectively, 8 WAA which was similar to saflufenacil/dimethenamid-p, mesotrione + atrazine and dicamba/atrazine. There was no treatment difference for corn yield. Based on these results, tolpyralate (40 g•ha −1), tolpyralate (30 g•ha −1) + atrazine and tolpyralate (40 g•ha −1

Long-Chain Molecules with Agro-Bioactivities and Their Applications

“…Tolpyralate is a new 4-HPPD-inhibitor that belongs to the benzoylpyrazole family that affects sensitive weeds by interrupting the biosynthesis of plastoquinone and tocopherol and stopping the synthesis of carotenoid pigments [163,165]. In comparison to other herbicides of the same class, tolpyralate delivers comparable or superior weed control in annual broadleaves and grasses [166,167].…”

“…Tolpyralate is a new 4-HPPDinhibitor that belongs to the benzoylpyrazole family that affects sensitive weeds by interrupting the biosynthesis of plastoquinone and tocopherol and stopping the synthesis of carotenoid pigments [163,165]. In comparison to other herbicides of the same class, tolpyralate delivers comparable or superior weed control in annual broadleaves and grasses [166,167]. Syringomycin (55), which is derived from Pseudomonas syringae, is a large amphiphilic molecule with a polar peptide head and a hydrophobic 3-hydroxy fatty acid tail of variable length (from C10 to C14) that binds to N-terminal serine residues via an amide bond [168] (Figure 27).…”