A major concern of sweetpotato producers is the potential negative effects from herbicide drift or sprayer contamination events when dicamba is applied to nearby dicamba-resistant crops. A field study was initiated in 2014 and repeated in 2015 to assess the effects of reduced rates of N,N-Bis-(3-aminopropyl)methylamine (BAPMA) or diglycloamine (DGA) salt of dicamba, glyphosate, or a combination of these individually in separate trials with glyphosate on sweetpotato. Reduced rates of 1/10, 1/100, 1/250, 1/500, 1/750, and 1/1,000 of the 1× use rate of each dicamba formulation at 0.56 kg ha−1, glyphosate at 1.12 kg ha−1, and a combination of the two at aforementioned rates were applied to ‘Beauregard’ sweetpotato at storage root formation (10 d after transplanting) in one trial and storage root development (30 d after transplanting) in a separate trial. Injury with each salt of dicamba (BAPMA or DGA) applied alone or with glyphosate was generally equal to or greater than glyphosate applied alone at equivalent rates, indicating that injury is most attributable to the dicamba in the combination. There was a quadratic increase in crop injury and a quadratic decrease in crop yield (with respect to most yield grades) observed with an increased herbicide rate of dicamba applied alone or in combination with glyphosate applied at storage root development. However, with a few exceptions, neither this relationship nor the significance of herbicide rate was observed on crop injury or sweetpotato yield when herbicide application occurred at the storage root formation stage. In general, crop injury and yield reduction were greatest at the highest rate (1/10×) of either salt of dicamba applied alone or in combination with glyphosate, although injury observed at lower rates would be cause for concern after initial observation by sweetpotato producers. However, in some cases yield reduction of No.1 and marketable grades was observed following 1/250×, 1/100×, or 1/10× application rates of dicamba alone or with glyphosate when applied at storage root development.

中文翻译：

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降低麦草畏和草甘膦用量对甘薯生长和产量的影响

甘薯生产者的一个主要问题是当麦草畏被施用于附近的麦草畏抗性作物时，除草剂漂移或喷雾器污染事件的潜在负面影响。一项实地研究于 2014 年启动，并于 2015 年重复进行，以评估降低 N,N-双-(3-氨基丙基)甲胺 (BAPMA) 或麦草畏、草甘膦或这些的组合的二甘草胺 (DGA) 盐的影响分别在甘薯上使用草甘膦的单独试验中。在 0.56 kg ha 时，每种麦草畏制剂的 1 倍使用率降低 1/10、1/100、1/250、1/500、1/750 和 1/1,000-1, 草甘膦 1.12 kg ha-1，并在一项试验中将上述比率的两种组合应用于“Beauregard”甘薯的贮藏根形成（移栽后 10 天）和贮藏根发育（移栽后 30 天）的单独试验。单独施用每种麦草畏盐（BAPMA 或 DGA）或与草甘膦一起施用的伤害通常等于或大于以相同速率单独施用的草甘膦，这表明伤害最可归因于组合中的麦草畏。随着麦草畏的除草剂用量增加或在贮藏根发育时与草甘膦联合施用，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，除了少数例外，在贮藏根形成阶段施用除草剂时，既没有观察到这种关系，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，单独施用或与草甘膦联合施用麦草畏盐的最高比率 (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会引起关注. 然而，在某些情况下，在储存根发育时单独使用麦草畏或与草甘膦合用 1/250 倍、1/100 倍或 1/10 倍的施用率后，观察到 1 号和可销售等级的产量降低。麦草畏盐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，以较低比率观察到的伤害将引起关注。然而，在某些情况下，在储存根发育时单独使用麦草畏或与草甘膦合用 1/250 倍、1/100 倍或 1/10 倍的施用率后，观察到 1 号和可销售等级的产量降低。麦草畏盐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，以较低比率观察到的伤害将引起关注。然而，在某些情况下，在储存根发育时单独使用麦草畏或与草甘膦合用 1/250 倍、1/100 倍或 1/10 倍的施用率后，观察到 1 号和可销售等级的产量降低。