Residual herbicides remain the primary tool for efficient weed control in cucurbit crops because of the lack of crop tolerance to many POST herbicide options. Field experiments were conducted in New Jersey in 2018 and 2019 to determine weed control efficacy and tolerance of direct-seeded cucumber ‘Python’ and summer squash ‘Gold Prize’ to S-metolachlor applied at 0.7 or 1.4 kg ai ha−1 at planting (PRE) or when crops reached the second- to third-leaf stage (EPOST). Regardless of applied rate, S-metolachlor PRE or EPOST provided 96% to 100% control 3 wk after planting (WAP) of smooth pigweed, large crabgrass, and giant foxtail. S-metolachlor PRE significantly improved American black nightshade and carpetweed control 3 WAP with respect to bensulide, and smooth pigweed with respect to clomazone + ethalfluralin. Summer squash showed excellent tolerance, regardless of S-metolachlor rate or timing of application, with stunting not exceeding 17% 4 WAP and 3% 7 WAP at the 1.4 kg ha−1 rate. Marketable yield decreased by 15% with S-metolachlor PRE or POST at 1.4 kg ha−1 with respect to clomazone + ethalfluralin, a reduction not noted when comparing with bensulide or the handweeded control. Marketable fruit number plant−1 and individual fruit weight were not affected by S-metolachlor applications. Conversely, cucumber was more sensitive to S-metolachlor than summer squash was with 30% seedling emergence reduction and 36% to 43% stunting 4 WAP when S-metolachlor was applied PRE at 1.4 kg ha−1. EPOST application resulted in 15% to 26% cucumber injury 1 wk after treatment. Marketable yield declined by 21% and 39% with the 0.7 and 1.4 kg ha−1 rates of S-metolachlor, respectively, compared with clomazone + ethalfluralin. Therefore, S-metolachlor may be a novel alternative to already labeled residual herbicides for summer squash, but unacceptable injury and yield reduction do not support its registration on cucumber.

中文翻译：

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S-异丙甲草胺在西葫芦和黄瓜种子中的杂草控制和作物耐受性

由于作物对许多 POST 除草剂选择缺乏耐受性，残留除草剂仍然是有效控制葫芦科作物杂草的主要工具。2018 年和 2019 年在新泽西州进行了田间试验，以确定直播黄瓜“蟒蛇”和西葫芦“金奖”的杂草控制效果和耐受性。小号-异丙甲草胺以 0.7 或 1.4 kg ai ha 施用-1在种植（PRE）或作物达到第二至第三叶阶段（EPOST）时。无论应用率如何，小号-异丙甲草胺 PRE 或 EPOST 提供了 96% 到 100% 的控制 3 周后 (WAP) 种植光滑的猪草、大马唐和巨型狐尾草。小号-异丙甲草胺 PRE 相对于苯舒利特显着改善了美国黑茄和地毯草的控制 3 WAP，相对于异恶草酮 + 氟尿嘧啶，显着改善了对杂草的控制。西葫芦表现出极好的耐受性，无论小号-异丙甲草胺施用率或施用时间，在 1.4 公斤公顷的土地上发育迟缓不超过 17% 4 WAP 和 3% 7 WAP-1速度。适销对路的收益率下降了 15%小号-异丙甲草胺 PRE 或 POST 在 1.4 kg ha-1对于异恶草酮 + 乙氧嘧啶，与苯舒利特或手工除草对照相比，没有注意到减少。适销水果号植物-1单果重不受影响小号-异丙甲草胺的应用。相反，黄瓜对小号-异丙甲草胺比西葫芦出苗减少 30% 和 36% 至 43% 的 4 WAP 时小号-异丙甲草胺以 1.4 kg ha 施用 PRE-1. EPOST 应用在治疗后 1 周导致 15% 至 26% 的黄瓜损伤。0.7 和 1.4 公斤公顷的可销售产量下降了 21% 和 39%-1率小号-异丙甲草胺分别与异恶草酮 + 乙氧嘧啶相比。所以，小号-异丙甲草胺可能是一种新的替代已标记的西葫芦残留除草剂，但不可接受的伤害和减产不支持其在黄瓜上的注册。