Organic vegetable farmers rely heavily on labor-intensive tillage for weed management, which adversely affects soil health and harms beneficial insects that consume crop pests and weed seeds. Using cover crop residues as a weed-suppressive mulch enables some reduction in tillage, and combining this tool with recently developed organic herbicides may further enhance weed suppression in vegetable production. However, organic herbicides may also adversely affect beneficial insects, and their nontarget effects are unknown. Here, we examine the combined impacts of cultural and chemical tools on weed cover while monitoring activity of beneficial epigeal insects and measuring rates of weed seed biological control to assess potential nontarget effects of organic herbicides. In a 2-yr experiment, we compared three cover crop mulch treatments and three organic herbicide treatments (capric/caprylic acid, corn gluten meal, and herbicide-free) in a reduced-tillage system. Organic herbicides led to no reductions in beneficial insect activity nor weed seed biocontrol. In both years, capric/caprylic acid herbicide and cover crop mulches reduced weed pressure relative to a fallow control treatment, whereas corn gluten meal had no effect. In year 2, a combination of cover crop mulch with organic herbicide had the greatest weed suppression relative to the fallow control. Integrated weed management is a perpetual challenge, but our results suggest that organic herbicides used in concert with cover crop mulch may enhance weed control and reduce the need for tillage, with limited collateral damage to natural enemies.

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在一起更好？在减耕系统中结合覆盖作物覆盖物、有机除草剂和杂草种子生物防治

有机蔬菜农民严重依赖劳动密集型耕作进行杂草管理，这对土壤健康产生不利影响，并危害消耗作物害虫和杂草种子的有益昆虫。使用覆盖作物残留物作为杂草抑制覆盖物可以减少耕作，并将该工具与最近开发的有机除草剂结合使用可以进一步增强蔬菜生产中的杂草抑制。然而，有机除草剂也可能对益虫产生不利影响，其非靶向作用尚不清楚。在这里，我们研究了文化和化学工具对杂草覆盖的综合影响，同时监测有益表生昆虫的活动并测量杂草种子生物防治率，以评估有机除草剂的潜在非目标效应。在为期 2 年的实验中，我们比较了减耕系统中的三种覆盖作物覆盖处理和三种有机除草剂处理（癸酸/辛酸、玉米蛋白粉和不含除草剂）。有机除草剂不会降低有益昆虫的活性，也不会降低杂草种子的生物防治。在这两年中，癸酸/辛酸除草剂和覆盖作物覆盖物相对于休耕控制处理降低了杂草压力，而玉米蛋白粉没有效果。在第 2 年，相对于休耕控制，覆盖作物覆盖物与有机除草剂的组合具有最大的杂草抑制作用。综合杂草管理是一项永恒的挑战，但我们的研究结果表明，有机除草剂与覆盖作物覆盖物配合使用可以增强杂草控制并减少耕作的需要，对天敌的附带损害有限。