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An online survey to better understand current weed management practices and concerns in Arkansas rice was distributed in the fall of 2020. A total of 123 respondents from across the Arkansas rice growing region returned the survey covering a total of 236,414 rice hectares, representing about 40% of the planted Arkansas rice hectares in 2020. The most problematic weeds were Echinochloa crus-galli (L.) P. Beauv. (ECG), Cyperus spp., and Oryza sativa L. (weedy rice), respectively, in flooded rice, and ECG, Amaranthus palmeri S. Wats., and Cyperus spp., respectively, in furrow-irrigated rice. Most respondents (78%) reported high concern with herbicide-resistant weeds, and crop rotation (>74%) was the most common strategy listed to control and mitigate the development of herbicide-resistant weeds. A chi-square test of homogeneity showed that strategies implemented to control herbicide-resistant weeds and mitigate the evolution of herbicide-resistant weeds were not dependent on occupation type (farmer, consultant, or industry rep) nor on years of involvement in rice production. Respondents failed to control ECG 44% of the time with their first postemergence herbicide. After initial herbicide failure, 53% of respondents stated two additional herbicide applications were required to control ECG escapes while another 21% of respondents stated it was never controlled. The average ECG population at 2020 harvest was between 0.1 and 1.0 plant m−2 according to 44% of the respondents; however, 41% of respondents indicated an ECG density of 2 to 10 plants m−2 at 2020 harvest. The reported annual average cost of herbicides for rice weed control was $266.40 ha−1 with ECG accounting for 81% of the total cost. Average yield loss attributed to ECG was estimated to be 505–959 kg ha−1 (economic loss of $134–254 ha−1). However, yield loss in the most heavily infested fields was estimated to be 757–1,464 kg ha−1 (economic loss of $200–387 ha−1). Effective, non-chemical approaches to weed management were ranked as the least important current research or educational effort, indicating a paradigm shift in rice producers' weed control line of thought is needed with dwindling herbicide options due to herbicide resistance.

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BACKGROUND Florpyrauxifen‐benzyl (FPB) is an arylpicolinate herbicide (Group IV) for barnyardgrass control in rice. One susceptible (Sus) and three putative FPB‐resistant (R1, R2, and R3) barnyardgrass biotypes were selected based on resistant/susceptible (R/S) ratios obtained from dose–response tests and used to investigate the potential resistance mechanisms. RESULTS Based on visual control results, the R/S ratios of barnyardgrass biotypes R1, R2, and R3 were 60‐, 33‐, and 16‐fold greater than the Sus standard, respectively. Sequencing results of TIR1 and AFB genes in the tested barnyardgrass revealed no difference between Sus and R barnyardgrass biotypes. Absorption of [14C]‐FPB in Sus barnyardgrass increased over time and reached 90%, which was >10 percentage points greater than that in R biotypes. The [14C]‐FPB absorption in all R barnyardgrass equilibrated after 48 h. For both Sus and R barnyardgrass, most [14C]‐FPB absorbed was present in the treated leaf (79.8–88.8%), followed by untreated aboveground (9.5–18.6%) and belowground tissues (1.3–2.2%). No differences in translocation were observed. Differences between Sus and R barnyardgrass biotypes were found for FPB metabolism. Production of the active metabolite, florpyrauxifen‐acid, was greater in Sus barnyardgrass (21.5–52.1%) than in R barnyardgrass (5.5–34.9%). CONCLUSION In conclusion, reductions in FPB absorption and florpyrauxifen‐acid production may contribute to the inability to control barnyardgrass with FPB. © 2021 Society of Chemical Industry.

A thorough understanding of commonly used herbicide application practices and technologies is needed to provide recommendations and determine necessary application education efforts. An online survey to assess ground and aerial herbicide application practices in Arkansas was made available online in spring 2019. The survey was direct-emailed to 272 agricultural aviators and 831 certified commercial pesticide applicators, as well as made publicly available online through multiple media sources. A total of 124 responses were received, of which 75 responses were specific to herbicide applications in Arkansas agronomic crops, accounting for approximately 49% of Arkansas’ planted agronomic crop hectares in 2019. Ground and aerial application equipment were used for 49 and 51% of the herbicide applications on reported hectares, respectively. Rate controllers were commonly used application technologies for both ground and aerial application equipment. In contrast, global positioning system-driven automatic nozzle and boom shut-offs were much more common on ground spray equipment than aerial equipment. Applicator knowledge of nozzles and usage was limited, regardless of ground or aerial applicators, as only 28% of respondents provided a specific nozzle type used, indicating a need for educational efforts on nozzles and their importance in herbicide applications. Of the reported nozzle types, venturi nozzles and straight stream nozzles were the most commonly used for ground and aerial spray equipment, respectively. Spray carrier volumes of 96.3 and 118.8 L ha-1 for ground spray equipment and 49.6 and 59.9 L ha-1 for aerial application equipment were the means of reported spray volumes for systemic and contact herbicides, respectively. Respondents indicated application optimization was a major benefit of utilizing newer application technologies, herbicide drift was a primary challenge, and expressed research needs included adjuvants, spray volume efficacy, and herbicide drift. Findings from this survey provided insight into current practices, technologies, and needs of Arkansas herbicide applicators. Research and education efforts can be implemented as a result to address aforementioned needs while providing applied research-based information to applicators based on current practices.