Currently, there are seven herbicides labeled for U.S. tobacco production; however, additional modes of action are greatly needed in order to reduce the risk of herbicide resistance. Field experiments were conducted at five locations during the 2017 and 2018 growing seasons to evaluate flue-cured tobacco tolerance to S-metolachlor applied pretransplanting incorporated (PTI) and pretransplanting (PRETR) at 1.07 (1×) and 2.14 (2×) kg ai ha−1. Severe injury was observed 6 wk after transplanting at the Whiteville environment in 2017 when S-metolachlor was applied PTI. End-of-season plant heights from PTI treatments at Whiteville were likewise reduced by 9% to 29% compared with nontreated controls, although cured leaf yield and value were reduced only when S-metolachlor was applied PTI at the 2× rate. Severe growth reduction was also observed at the Kinston location in 2018 where S-metolachlor was applied at the 2× rate. End-of-season plant heights were reduced 11% (PTI, 2×) and 20% (PRETR, 2×) compared with nontreated control plants. Cured leaf yield was reduced in Kinston when S-metolachlor was applied PRETR at the 2× rate; however, treatments did not impact cured leaf quality or value. Visual injury and reductions in stalk height, yield, quality, and value were not observed at the other three locations. Ultimately, it appears that injury potential from S-metolachlor is promoted by coarse soil texture and high early-season precipitation close to transplanting, both of which were documented at the Whiteville and Kinston locations. To reduce plant injury and the negative impacts to leaf yield and value, application rates lower than 1.07 kg ha−1 may be required in these scenarios.

中文翻译：

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烤烟对异丙甲草胺的耐受性

目前，有七种除草剂标签用于美国烟草生产；然而，为了降低除草剂抗药性的风险，非常需要额外的作用方式。在 2017 年和 2018 年生长季节期间，在五个地点进行了田间试验，以评估烤烟耐受性小号-异丙甲草胺以 1.07 (1×) 和 2.14 (2×) kg ai ha 施用移植前掺入 (PTI) 和移植前 (PRETR)-1. 2017 年在 Whiteville 环境移植后 6 周观察到严重损伤，当时小号-异丙甲草胺用于PTI。与未处理的对照相比，Whiteville 的 PTI 处理的季末植物高度同样降低了 9% 至 29%，尽管只有在小号-异丙甲草胺以 2 倍的速率应用 PTI。2018 年在金斯顿的地点也观察到了严重的增长下降，小号-异丙甲草胺以 2 倍的速率施用。与未经处理的对照植物相比，季末植物高度降低了 11% (PTI, 2x) 和 20% (PRETR, 2x)。金斯顿的腌叶产量下降小号-异丙甲草胺以 2 倍的速率使用 PRETR；然而，处理并不影响治愈叶片的质量或价值。在其他三个位置没有观察到视觉损伤和茎高、产量、质量和价值的降低。最终，似乎受伤的可能性来自小号-异丙甲草胺因土壤质地粗糙和接近移栽的早季降水量高而得到促进，怀特维尔和金斯顿的地点均记录了这两种情况。为减少植物伤害和对叶片产量和价值的负面影响，施用量低于 1.07 kg ha-1在这些情况下可能需要。