Commercialization of 2,4-D–tolerant crops is a major concern for sweetpotato producers because of potential 2,4-D drift that can cause severe crop injury and yield reduction. A field study was initiated in 2014 and repeated in 2015 to assess impacts of reduced rates of 2,4-D, glyphosate, or a combination of 2,4-D with glyphosate on sweetpotato. In one study, 2,4-D and glyphosate were applied alone and in combination at 1/10, 1/100, 1/250, 1/500, 1/750, and 1/1,000 of anticipated field use rates (1.05 kg ha−1 for 2,4-D and 1.12 kg ha−1 for glyphosate) to ‘Beauregard’ sweetpotato at storage root formation (10 days after transplanting [DAP]). In a separate study, all these treatments were applied to ‘Beauregard’ sweetpotato at storage root development (30 DAP). Injury with 2,4-D alone or in combination with glyphosate was generally equal or greater than with glyphosate applied alone at equivalent herbicide rates, indicating that injury is attributable mostly to 2,4-D in the combination. There was a quadratic increase in crop injury and quadratic decrease in crop yield (with respect to most yield grades) with increased rate of 2,4-D applied alone or in combination with glyphosate applied at storage root development. However, neither the results of this relationship nor of the significance of herbicide rate were observed on crop injury or sweetpotato yield when herbicide application occurred at storage root formation, with a few exceptions. In general, crop injury and yield reduction were greatest at the highest rate (1/10×) of 2,4-D applied alone or in combination with glyphosate, although injury observed at lower rates was also a concern after initial observation by sweetpotato producers. However, in some cases, yield reduction of U.S. no.1 and marketable grades was also observed after application of 1/250×, 1/100×, or 1/10× rates of 2,4-D alone or with glyphosate when applied at storage root development.

中文翻译：

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降低 2,4-D 和草甘膦的用量对甘薯生长和产量的影响

耐 2,4-D 作物的商业化是甘薯生产者的主要关注点，因为潜在的 2,4-D 漂移会导致严重的作物伤害和减产。一项实地研究于 2014 年启动，并于 2015 年重复进行，以评估降低 2,4-D、草甘膦或 2,4-D 与草甘膦的组合对甘薯的影响。在一项研究中，2,4-D 和草甘膦单独使用或组合使用，分别为预期田间使用率的 1/10、1/100、1/250、1/500、1/750 和 1/1,000（1.05 kg哈-1适用于 2,4-D 和 1.12 kg ha-1草甘膦）在贮藏根形成时（移栽后 10 天 [DAP]）转化为“Beauregard”甘薯。在另一项研究中，所有这些处理均应用于贮藏根发育（30 DAP）的“Beauregard”甘薯。单独使用 2,4-D 或与草甘膦结合使用的伤害通常等于或大于在相同除草剂用量下单独使用草甘膦，这表明伤害主要归因于组合中的 2,4-D。随着 2,4-D 单独施用或与草甘膦在贮藏根发育过程中施用的比例增加，作物伤害呈二次增长，作物产量（相对于大多数产量等级）呈二次下降。然而，当除草剂应用发生在贮藏根形成时，除少数例外情况外，没有观察到这种关系的结果，也没有观察到除草剂用量对作物伤害或甘薯产量的意义。一般而言，2,4-D 单独施用或与草甘膦联合施用的最高比率 (1/10 倍) 作物伤害和减产幅度最大，尽管在甘薯生产者初步观察后观察到较低比率的伤害也是一个问题. 然而，在某些情况下，在单独施用 1/250×、1/100× 或 1/10× 的 2,4-D 或与草甘膦一起施用时，也观察到美国 1 号和市售品级的产量降低在储存根发育。4-D 单独施用或与草甘膦联合施用，尽管在甘薯生产者初步观察后，以较低的比率观察到的伤害也是一个问题。然而，在某些情况下，在单独施用 1/250×、1/100× 或 1/10× 的 2,4-D 或与草甘膦一起施用时，也观察到美国 1 号和市售品级的产量降低在储存根发育。4-D 单独施用或与草甘膦联合施用，尽管在甘薯生产者初步观察后，以较低的比率观察到的伤害也是一个问题。然而，在某些情况下，在单独施用 1/250×、1/100× 或 1/10× 的 2,4-D 或与草甘膦一起施用时，也观察到美国 1 号和市售品级的产量降低在储存根发育。