The herbicide 2,4-D is used in a variety of cropping systems, especially in grasses because it is a selective postemergence broadleaf herbicide. However, the most common formulation (2,4-D dimethylamine) is antagonized when mixed in hard water. The objective of this research was to determine which formulations of 2,4-D or premixes of various formulations of synthetic auxin herbicides are subject to hard water antagonism. Formulations surveyed for hard water antagonism in the first experiment included 2,4-D dimethylamine, 2,4-D diethanolamine, 2,4-D monomethylamine, 2,4-D isopropylamine salt, 2,4-D choline salt, 2,4-D isooctyl ester, and 2,4-D ethylhexyl ester. Synthetic auxin formulation types in the second experiment included water-soluble, emulsifiable concentrates and emulsion-in-water. All formulations were mixed with both soft and hard water (600 mg CaCO3 L−1) and applied to dandelions to determine whether antagonism occurred in hard water. Water-soluble (amine and choline) 2,4-D formulations were antagonized by hard water, but water-insoluble (ester) 2,4-D formulations were not antagonized. Similar results were found by formulation type with water-soluble synthetic auxin premixes antagonized but emulsifiable concentrates not antagonized. Furthermore, water-soluble salt formulations were not antagonized when formulated in premixes with other synthetic auxin herbicides as an emulsion-in-water. This research demonstrates that all 2,4-D water-soluble formulations and water-soluble premixes with phenoxycarboxylic acid herbicides are subject to hard water antagonism. Formulations of 2,4-D containing emulsifying agents protect against antagonism by the water-insoluble nature of ingredients in their formulation.

中文翻译：

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硬水对控制蒲公英的 2,4-D 配方的影响

除草剂 2,4-D 用于多种种植系统，特别是在禾本科植物中，因为它是一种选择性芽后阔叶除草剂。然而，最常见的配方（2,4-D 二甲胺）在硬水中混合时会产生拮抗作用。本研究的目的是确定哪些 2,4-D 制剂或各种合成生长素除草剂制剂的预混物会受到硬水拮抗作用。在第一个实验中调查的硬水拮抗剂配方包括 2,4-D 二甲胺、2,4-D 二乙醇胺、2,4-D 单甲胺、2,4-D 异丙胺盐、2,4-D 胆碱盐、2、 4-D 异辛酯和 2,4-D 乙基己酯。第二个实验中的合成生长素制剂类型包括水溶性、乳油和水包乳剂。3大号-1) 并应用于蒲公英以确定是否在硬水中发生拮抗作用。水溶性（胺和胆碱）2,4-D 制剂被硬水拮抗，但水不溶性（酯）2,4-D 制剂没有被拮抗。通过拮抗水溶性合成生长素预混物但未拮抗乳油的制剂类型发现了类似的结果。此外，水溶性盐制剂在与其他合成生长素除草剂预混配制成水包乳剂时没有拮抗作用。该研究表明，所有 2,4-D 水溶性制剂和与苯氧基羧酸除草剂的水溶性预混物都具有硬水拮抗作用。2的配方，