Palmer amaranth is one of the most difficult-to-control weeds in row crop systems and has evolved resistance to several herbicide sites of action (SOAs). A late-season weed-escape survey had been conducted earlier to determine the distribution of protoporphyrinogen oxidase–inhibitor resistant Palmer Amaranth in Arkansas. The objective of this study was to evaluate the susceptibility of Arkansas Palmer amaranth accessions to commonly used herbicide SOAs. The SOAs evaluated were group 2 + 9, 3, 4, 5, 10, 14, 15, and 27, and the representative herbicide from each group was imazethapyr + glyphosate (79 + 860 g ha−1), trifluralin (1,120 g ha−1), dicamba (280 and 560 g ha−1), atrazine (560 g ha−1), glufosinate (594 g ha−1), fomesafen (395 g ha−1), S-metolachlor (1,064 g ha−1), and tembotrione (92 g ha−1), respectively. Palmer amaranth mortality varied among accessions across SOAs. Averaged across accessions, the mortality rates, by treatment in order from lowest to highest, were as follows: glyphosate + imazethapyr (16%), tembotrione (51%), dicamba at 280 g ha−1 (51%), fomesafen (76%), dicamba at 560 g ha−1 (82%), atrazine (85%), trifluralin (87%), S-metolachlor (96%), and glufosinate (99.5%). This study provides evidence that Palmer amaranth accessions with low susceptibility to glyphosate + imazethapyr, fomesafen, and tembotrione are widespread throughout Arkansas. Of the remaining SOAs, most Palmer amaranth accessions were sensitive; however, within each herbicide SOA, except glufosinate, control of some accessions was less than expected and resistance is suspected.

中文翻译：

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阿肯色州帕尔默苋菜种质对常见除草剂作用位点的敏感性

苋菜是行作物系统中最难控制的杂草之一，并且已经进化出对几种除草剂作用位点 (SOA) 的抗性。早些时候进行了一项晚季杂草逃生调查，以确定阿肯色州抗原卟啉原氧化酶抑制剂的帕尔默苋菜的分布。本研究的目的是评估阿肯色州帕尔默苋菜种质对常用除草剂 SOA 的敏感性。评估的 SOA 为第 2 + 9、3、4、5、10、14、15 和 27 组，每组的代表性除草剂为咪草烟 + 草甘膦（79 + 860 g ha-1)、氟乐灵 (1,120 g ha-1)、麦草畏 (280 和 560 g ha-1)，阿特拉津（560 克公顷-1)、草铵膦 (594 g ha-1)、氟虫草醚 (395 g ha-1),小号-异丙甲草胺（1,064 克公顷-1) 和 tembotrione (92 g ha-1）， 分别。帕尔默苋菜死亡率因 SOA 的加入而异。不同种质的平均死亡率，按治疗从低到高的顺序如下：草甘膦+咪草烟（16%）、tembotrione（51%）、麦草畏，280 g ha-1(51%)、氟虫草醚 (76%)、麦草畏 560 g ha-1(82%)、阿特拉津 (85%)、氟乐灵 (87%)、小号-异丙甲草胺 (96%) 和草铵膦 (99.5%)。这项研究提供的证据表明，对草甘膦 + 咪草烟、氟磺胺草醚和 tembotrione 的敏感性较低的帕尔默苋菜种质在阿肯色州普遍存在。在剩余的 SOA 中，大多数 Palmer 苋菜种属是敏感的；然而，在每种除草剂 SOA 中，除草铵膦外，对一些种质的控制低于预期，并且怀疑存在抗药性。