Italian ryegrass [Lolium perenne L. spp. multiflorum (Lam.) Husnot] is one of the most troublesome weeds worldwide. Lolium multiflorum is also a grass seed crop cultivated on 50,000 ha in Oregon, where both diploid and tetraploid cultivars are grown. For this work, we will refer to the species as L. multiflorum, since the common names annual ryegrass and Italian ryegrass both refer to the same species. A survey was conducted to understand the distribution and frequency of L. multiflorum and its susceptibility to selected herbicides used in its control. The herbicides selected were clethodim, glufosinate, glyphosate, mesosulfuron-methyl (mesosulfuron), paraquat, pinoxaden, pyroxsulam, quizalofop-P-ethyl (quizalofop), pronamide, flufenacet + metribuzin, and pyroxasulfone. The ploidy levels of the populations were also tested. A total of 150 fields were surveyed between 2017 and 2018, of which 75 (50%) had L. multiflorum present. Herbicide-resistant populations were documented in 88% of the 75 populations collected. The most frequent resistances were to acetyl-CoA carboxylase (ACCase), acetolactate synthase (ALS), 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) inhibitors, and combinations thereof. Multiple resistance and cross-resistance, found in 75% of the populations, were the most frequent patterns of resistance. Paraquat-resistant biotypes were confirmed in six orchard crop populations for the first time in Oregon. Herbicide resistance was spatially clustered, with most cases of resistance in the northern part of the surveyed area. Populations resistant to ALS and ACCase inhibitors were prevalent in wheat (Triticum aestivum L.) fields. Multiple resistance was positively correlated with plant density. Tetraploid feral populations were identified, but no cases of herbicide resistance were documented. This is the first survey of herbicide resistance and ploidy diversity in L. multiflorum in western Oregon. Resistant populations were present across the surveyed area, indicating that the problem is widespread.

中文翻译：

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俄勒冈州西部抗除草剂意大利黑麦草 (Lolium perenne spp. multiflorum) 种群的频率、分布和倍性多样性

意大利黑麦草 [黑麦草L. spp。何首乌(Lam.) Husnot] 是世界上最麻烦的杂草之一。何首乌也是一种草种作物，在俄勒冈州的 50,000 公顷土地上种植，种植二倍体和四倍体品种。对于这项工作，我们将物种称为何首乌，因为通用名称一年生黑麦草和意大利黑麦草都指的是同一物种。进行了一项调查以了解其分布和频率何首乌及其对控制中使用的选定除草剂的敏感性。选择的除草剂是烯草酮、草铵膦、草甘膦、甲基磺草胺（mesosulfuron）、百草枯、吡诺草胺、吡唑磺草胺、喹草灵（quizalofop）、普诺米特、氟灭草胺 + 灭草灵和吡虫啉。还测试了种群的倍性水平。2017 年至 2018 年间共调查了 150 个领域，其中 75 个（50%）何首乌展示。在收集的 75 个种群中，有 88% 记录了抗除草剂种群。最常见的耐药性是对乙酰辅酶A羧化酶 (ACCase)、乙酰乳酸合酶 (ALS)、5-烯醇丙酮酸莽草酸-3-磷酸合酶 (EPSPS) 抑制剂及其组合。在 75% 的人群中发现多重耐药和交叉耐药是最常见的耐药模式。俄勒冈州首次在六个果园作物种群中证实了百草枯抗性生物型。除草剂抗药性呈空间聚集性，大部分抗药发生在调查区北部。抗 ALS 和 ACCase 抑制剂的种群在小麦中普遍存在（小麦L.) 字段。多重抗性与植物密度呈正相关。确定了四倍体野生种群，但没有记录到除草剂抗性的情况。这是对除草剂抗性和倍性多样性的首次调查何首乌在俄勒冈州西部。整个调查区域都存在抗药性种群，表明该问题很普遍。