Horseweed is a competitive summer or winter annual weed that produces up to 230,000 small seeds per plant that are capable of traveling more than 500 km via wind. Giant ragweed is a tall, highly competitive summer annual weed. Glyphosate-resistant (GR) horseweed and GR giant ragweed pose significant challenges for producers in the United States and Ontario, Canada. It is thought that an integrated weed management (IWM) system involving herbicide rotation is required to control GR biotypes. Halauxifen-methyl is a new selective broadleaf POST herbicide registered for use in cereal crops; there is limited information on its efficacy on horseweed and giant ragweed. The purpose of this research was to determine the efficacy of halauxifen-methyl applied POST, alone and in a tank mix, for the control of GR horseweed and GR giant ragweed in wheat across southwestern Ontario. For each weed species, an efficacy study consisting of six field experiments was conducted over a 2-yr period (2018, 2019). At 8 wk after application (WAA), halauxifen-methyl, fluroxypyr/halauxifen-methyl, fluroxypyr/halauxifen-methyl + MCPA EHE, fluroxypyr + MCPA ester, 2,4-D ester, clopyralid, and pyrasulfotole/bromoxynil + ammonium sulfate controlled GR horseweed >95%. Fluroxypyr and MCPA provided only 86% and 37% control of GR horseweed, respectively. At 8 WAA, fluroxypyr, fluroxypyr/halauxifen-methyl, fluroxypyr/halauxifen-methyl + MCPA EHE, fluroxypyr + MCPA ester, fluroxypyr/halauxifen-methyl + MCPA EHE + pyroxsulam, 2,4-D ester, clopyralid, and thifensulfuron/tribenuron + fluroxypyr + MCPA ester controlled GR giant ragweed 87%, 88%, 90%, 94%, 96%, 96%, 98%, and 93%, respectively. Halauxifen-methyl and pyroxsulam provided only 45% and 28% control of GR giant ragweed, respectively. Halauxifen-methyl applied alone POST in the spring controlled GR horseweed but not GR giant ragweed in winter wheat.

中文翻译：

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Halauxifen-methyl 控制冬小麦中抗草甘膦的马草 (Conyza canadensis) 但不控制巨型豚草 (Ambrosia trifida)

马草是一种具有竞争力的夏季或冬季一年生杂草，每株可产生多达 230,000 粒小种子，能够通过风传播超过 500 公里。巨型豚草是一种高大、竞争激烈的夏季一年生杂草。抗草甘膦 (GR) 马草和 GR 巨型豚草对美国和加拿大安大略省的生产商构成重大挑战。人们认为需要一个涉及除草剂轮换的综合杂草管理 (IWM) 系统来控制 GR 生物型。Halauxifen-methyl 是一种新的选择性阔叶 POST 除草剂，已注册用于谷类作物；关于其对马草和巨型豚草的功效的信息有限。本研究的目的是确定单独使用和在桶混中应用 POST 的甲基卤代芬的功效，用于控制安大略省西南部小麦中的 GR 马草和 GR 巨型豚草。对于每种杂草，在 2 年期间（2018 年、2019 年）进行了一项由六个田间试验组成的功效研究。在施用后 8 周 (WAA)，氟草烟/甲基氟草烟、氟草烟/甲基氟草烟 + MCPA EHE、氟草烟 + MCPA 酯、2,4-D 酯、氯吡菌胺和吡嘧磺草胺/溴苯腈 + 硫酸铵受控GR 马草 >95%。氟草烟和 MCPA 分别仅提供 86% 和 37% 的 GR 马草控制。8 WAA、氟草烟、氟草烟/甲基氟草醚、氟草烟/甲基氟草醚 + MCPA EHE、氟草烟 + MCPA 酯、氟草烟/甲基氟草醚 + MCPA EHE + pyroxsulam、2,4-D 酯、氯吡嘧啶和噻吩磺隆/苯磺隆+ 氟草烟 + MCPA 酯控 GR 大豚草 87%、88%、90%、94%、96%、分别为 96%、98% 和 93%。Halauxifen-methyl 和 pyroxsulam 分别仅对 GR 巨型豚草提供 45% 和 28% 的控制。Halauxifen-methyl 单独施用 POST 在春季控制 GR 马草中，而不是在冬小麦中控制 GR 巨型豚草。