Weed control in tree nut orchards is a year-round challenge for growers that is particularly intense during winter through summer as a result of competition and interference with management and harvest operations. A common weed control program consists of an application of a winter PRE and POST herbicide mixture, followed by a desiccation treatment in early spring and before harvest. Because most spring and summer treatments depend on a limited number of foliar-applied herbicides, summer-germinating species and/or herbicide-resistant biotypes become troublesome. Previous research has established effective PRE herbicide programs targeting winter glyphosate-resistant weeds. However, more recently, growers have reported difficulties in controlling several summer-germinating grass weeds with documented or suspected resistance to the spring and summer POST herbicide programs. In this context, research was conducted to evaluate a sequential PRE approach to control winter- and summer-germinating orchard weeds. Eight field experiments were conducted in tree nut orchards to evaluate the efficacy of common winter herbicide programs and a sequential herbicide program for control of a key summer grass weed species. In the sequential-application strategy, three foundational herbicide programs applied in the winter were either mixed with pendimethalin, followed with pendimethalin in March, or applied as a split application of pendimethalin in both winter and spring. Results indicate that the addition of pendimethalin enhanced summer grass weed control throughout the crop growing season by up to 31%. Applying all or part of the pendimethalin in the spring improved control of the summer grass weed junglerice by up to 49%. The lower rate of pendimethalin applied in the spring performed as well as the high rate in the winter, suggesting opportunities for reducing herbicide inputs. Tailoring sequential herbicide programs to address specific weed challenges can be a viable strategy for improving orchard weed control without increasing herbicide use in some situations.

中文翻译：

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加利福尼亚树坚果作物中使用连续除草剂计划的季节杂草控制

坚果园的杂草控制对种植者来说是全年的挑战，由于竞争和对管理和收获操作的干扰，在冬季到夏季尤其激烈。一个常见的杂草控制计划包括应用冬季前后除草剂混合物，然后在早春和收获前进行干燥处理。由于大多数春季和夏季处理依赖于有限数量的叶面除草剂，夏季发芽物种和/或抗除草剂生物型变得很麻烦。先前的研究已经建立了针对冬季抗草甘膦杂草的有效 PRE 除草剂计划。然而，最近，种植者报告说难以控制几种夏季发芽的杂草，这些杂草已记录或怀疑对春季和夏季 POST 除草剂计划具有抗性。在这种情况下，进行了研究以评估用于控制冬季和夏季发芽的果园杂草的顺序 PRE 方法。在坚果果园进行了八次田间试验，以评估常见的冬季除草剂方案和顺序除草剂方案控制夏季主要禾本科杂草的效果。在顺序施用策略中，在冬季施用的三种基础除草剂方案要么与二甲戊灵混合，然后在 3 月施用二甲戊灵，要么在冬季和春季分开施用二甲戊灵。结果表明，添加二甲戊灵可在整个作物生长季节将夏季禾本科杂草控制效果提高 31%。春季施用全部或部分二甲戊灵可提高对夏季禾本科杂草丛林稻的控制达 49%。春季施用二甲戊灵的较低比率与冬季较高的施用率一样，表明有机会减少除草剂的投入。在某些情况下，在不增加除草剂使用的情况下，定制连续除草剂计划以应对特定的杂草挑战可能是改善果园杂草控制的可行策略。春季施用二甲戊灵的较低比率与冬季较高的施用率一样，表明有机会减少除草剂的投入。在某些情况下，在不增加除草剂使用的情况下，定制连续除草剂计划以应对特定的杂草挑战可能是改善果园杂草控制的可行策略。春季施用二甲戊灵的较低比率与冬季较高的施用率一样，表明有机会减少除草剂的投入。在某些情况下，在不增加除草剂使用的情况下，定制连续除草剂计划以应对特定的杂草挑战可能是改善果园杂草控制的可行策略。