Cowpea bean (Vigna unguiculata) is usually submitted to pre-harvest burndown with herbicides aiming to an early harvest. We aimed to quantify the residues of paraquat, diquat, glufosinate-ammonium and glyphosate in cowpea grains subjected to two timings of pre-harvest burndown. Three identical experiments were installed in Dourados (Lat. 22° S), Sinop (Lat. 11° S) and Teresina (Lat. 05° S), Brazil, comprising the pre-harvest burndown of cowpea bean with these herbicides, applied either with 50 or 75% of the pods dry and ready for harvest. As hotter and drier the location as slower the herbicide dissipation. Glyphosate should not be used for pre-harvest burndown of cowpea. Herbicide residues were above the maximum levels stated by the Brazilian legislation when applied with 50% dry pods. Burndown herbicides aiming to speed harvest should be applied with at least 75% dry pods in cowpea to ensure safe herbicide residue levels in grains.

中文翻译：

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豇豆 (Vigna unguiculata) 籽粒采前烧毁除草剂残留

豇豆（豇豆) 通常使用旨在提早收获的除草剂进行收获前焚烧处理。我们旨在量化经过两次收获前焚烧处理的豇豆籽粒中的百草枯、敌草快、草铵膦和草甘膦残留量。在巴西的 Dourados（南纬 22°）、锡诺普（南纬 11°）和特雷西纳（南纬 05°）进行了三个相同的实验，包括使用这些除草剂对豇豆的收获前焚烧， 50% 或 75% 的豆荚干燥并准备好收获。位置越热越干燥，除草剂消散越慢。草甘膦不应用于豇豆的收获前焚烧。当使用 50% 的干豆荚时，除草剂残留量高于巴西立法规定的最高水平。