Glyphosate is an important component of herbicide programs in orchard crops in California. It can be applied alone or in tank-mix combinations under the crop rows or to the entire field and often is used multiple times each year. There has been speculation about the potential impacts of repeated use of glyphosate in perennial crop systems, because of uptake from shallow root systems or indirectly because of effects on nutrient availability in soil. To address these concerns, research was conducted from 2013 to 2020 on key orchard crops to evaluate tree response to glyphosate regimens. Almond, cherry, and prune were evaluated in separate experiments. In each crop, the experimental design was a factorial arrangement of two soil types, four glyphosate rates (0, 1.1, 2.2, and 4.4 kg ae ha−1, applied three times annually), and two post-glyphosate application irrigation treatments. In the first 2 yr of the study, there was no clear impact of the glyphosate regimens on shikimate accumulation or leaf chlorophyll content, which suggested no direct effect on the crop. In the seventh year of the study, after six consecutive years of glyphosate application to the orchard floors, there were no negative impacts of glyphosate application on leaf nutrient concentration or on cumulative trunk growth in any of the three orchard crops. Lack of a negative growth impact even at the highest treatment rate, which included 18 applications of glyphosate totaling nearly 80 kg ae ha−1 glyphosate over the course of the experiment suggest there is not likely a significant risk to tree health of judicious use of the herbicide in these production systems. Given the economic importance of orchard crops in California, and grower and industry concerns about pesticides generally and specifically about glyphosate, these findings are timely contributions to weed management concerns in perennial specialty crops.

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重复使用草甘膦对果园作物生长的影响

草甘膦是加利福尼亚果园作物除草剂计划的重要组成部分。它可以单独使用，也可以在作物行下或整个田间混合使用，并且通常每年使用多次。由于从浅根系统吸收或间接由于对土壤养分有效性的影响，人们猜测在多年生作物系统中重复使用草甘膦的潜在影响。为了解决这些问题，2013 年至 2020 年对主要果园作物进行了研究，以评估树木对草甘膦方案的反应。杏仁、樱桃和李子在单独的实验中进行了评估。在每种作物中，实验设计是两种土壤类型、四种草甘膦用量（0、1.1、2.2 和 4.4 kg ae ha-1，每年施用三次）和两次草甘膦施用后灌溉处理。在研究的前 2 年，草甘膦方案对莽草酸积累或叶片叶绿素含量没有明显影响，这表明对作物没有直接影响。在研究的第七年，在果园地面连续六年施用草甘膦后，草甘膦施用对三种果园作物的叶片养分浓度或累积树干生长没有负面影响。即使在最高处理率下也没有负面增长影响，其中包括 18 次草甘膦施用，总计近 80 kg ae ha-1整个实验过程中的草甘膦表明，在这些生产系统中明智地使用除草剂不会对树木健康造成重大风险。鉴于加州果园作物的经济重要性，以及种植者和行业对农药的普遍关注，特别是对草甘膦的关注，这些发现及时有助于解决多年生特种作物的杂草管理问题。