Abstract
AbstractMany factors such as environment, herbicide rate, growth stage at application, and days between sequential applications can influence the response of a crop to herbicides. Florpyrauxifen-benzyl is a new broad-spectrum, POST herbicide that was commercialized for use in U.S. rice production in 2018. Field experiments were conducted in 2018 at the Pine Tree Research Station (PTRS) near Colt, AR, and the Rice Research and Extension Center (RREC), near Stuttgart, AR, to evaluate crop injury and yield response of three rice cultivars to sequential applications of florpyrauxifen-benzyl. Greenhouse and growth chamber experiments were conducted at the Altheimer Laboratory in Fayetteville, AR, to evaluate cultivar responses when florpyrauxifen-benzyl was applied at 30 or 60 g ae ha−1 to rice exposed to different temperature regimes or at various growth stages. Three rice cultivars were used in all experiments: long-grain variety ‘CL111’, medium-grain variety ‘CL272’, and long-grain hybrid cultivar ‘CLXL745’. CL111 exhibited sufficient tolerance to florpyrauxifen-benzyl with only 10% visible injury and no effect on yield. CL272 showed 15% injury 3 wk after the second application in the field experiment when applications were made 14 d apart. Additionally, 12% injury was observed in greenhouse studies when florpyrauxifen-benzyl was applied at 30 g ae ha−1, averaged over various growth stages at application. Florpyrauxifen-benzyl did not reduce the yield of CL272 in field experiments, indicating that CL272 can recover from florpyrauxifen-benzyl injury. As much as 64% injury was observed for CLXL745 at 3 wk after application (WAA) when sequential herbicide applications were made 4 d apart. High levels of injury occurred in the growth chamber and greenhouse studies for this cultivar as well. Sequential applications of florpyrauxifen-benzyl reduced yields of CLXL745 in nearly all treatments. Data from these experiments suggest that CL272 and CLXL745 are sensitive to sequential applications of florpyrauxifen-benzyl. Growers must follow the prescribed guidelines for using florpyrauxifen-benzyl in these cultivars and others like it.
Highlights
Florpyrauxifen-benzyl is a new synthetic auxin herbicide (Weed Science Society of America [WSSA] Group 4) released for commercial use in rice in 2018 by Corteva Agriscience
The field experiment conducted on CL111 showed florpyrauxifenbenzyl had little effect on this cultivar
CL111 was injured less than 10% at 3 wk after sequential applications (WAA) of florpyrauxifen-benzyl, regardless of herbicide rate (Table 3)
Summary
Florpyrauxifen-benzyl is a new synthetic auxin herbicide (Weed Science Society of America [WSSA] Group 4) released for commercial use in rice in 2018 by Corteva Agriscience. Previous research has explored both the weed control spectrum and the chemical properties of the herbicide, including residual activity and translocation. Florpyrauxifen-benzyl controls many troublesome weeds in rice production, including yellow nutsedge (Cyperus esculentus L.), hemp sesbania [Sesbania herbacea (Mill.) McVaugh], and barnyardgrass [Echinochloa crus-galli (L.) P. Florpyrauxifen-benzyl has a site of action that is different than that of quinclorac (WSSA Group 4), favoring the AFB5 IAA co-receptor instead of the TIR1 co-receptor, which allows florpyrauxifen-benzyl to have activity on quinclorac-resistant barnyardgrass (Lee et al 2014; Miller et al 2018; Walsh et al 2006). Florpyrauxifen-benzyl has minimal residual activity and should be used in conjunction with a herbicide with residual activity to control weeds with prolonged emergence (Miller and Norsworthy 2018b). Florpyrauxifenbenzyl can be applied at 30 g ae ha−1, with a maximum of two applications per growing season (Anonymous 2017)
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