For optimum postemergence crabgrass (Digitaria spp.) control, a single quinclorac herbicide application could be properly timed and delivered with spray nozzles that produce spray droplets ranging from very coarse (401-500 μm) to medium (226-325 μm) in size to maximize target coverage and minimize the potential for drift. Crabgrass is an invasive annual grass weed of cool-season turfgrass maintain as lawns, golf courses, and sports pitches. Postemergence herbicide applications for crabgrass control in turfgrass swards often rely on repeated applications for effective control. Optimizing postemergence crabgrass applications can reduce pesticide inputs and contribute to sustainable turfgrass management practices. Two field studies evaluating crabgrass control were conducted in 2020 in a mixed stand of Kentucky bluegrass (Poa pratensis L.) with perennial ryegrass (Lolium perenne L.) in Ohio (USA) and in perennial ryegrass in Pennsylvania (USA). Both sites have histories of natural crabgrass [Digitaria sanguinalis (L.) Scop.] infestation. A postemergence herbicide, quinclorac, was applied at the product label rate and tank-mixed with methylated seed oil at the crabgrass plant stage of three-leaf to one tiller. Different spray nozzles were selected to deliver the following spray droplet classifications and sizes at 275 kPa: Delavan Raindrop 1/4, ultra coarse (>650 μm); TurfJet 1/4TTJO4, extremely coarse (501-650 μm); Air Induction AA8004 or XRTeeJet 8015, very coarse (401-500 μm); XR TeeJet 8008 or GreenLeaf TDAD04, coarse (326-400 μm); XR TeeJet 8004, medium (226-325 μm); and XRTeeJet 8003 fine (145-225 μm). Crabgrass pressure was low in Ohio, and herbicide efficacy at 60 days after treatment was considered acceptable when applied from all spray nozzles that produced spray droplet sizes ranging from ultra coarse to fine. Crabgrass pressure was severe in Pennsylvania, and herbicide efficacy at 60 DAT was considered marginally acceptable when applied from spray nozzles that produced spray droplet sizes ranging from very coarse to medium. Future research should consider cultural practices that would be complementary to postemergence herbicide applications with the goal to reduce pesticide use further and minimize any potential environmental impacts related to spray drift.Highlights - In turfgrass sites with low crabgrass pressure, one postemergence application of quinclorac herbicide could potentially achieve acceptable control with spray nozzles that produce spray droplets ranging from ultra coarse (>650 μm) to fine (145-225 μm). - In turfgrass sites with heavy crabgrass population and pressure, one postemergence application of quinclorac herbicide is best optimized with spray nozzles that produce spray droplets ranging from very coarse (401-500 μm) to medium (226-325 μm). - Overall, turfgrass management practitioners should avoid using spray nozzles that produce a hollow cone spray pattern with ultra coarse (>650 μm) spray droplets which can result in poor or irregular herbicide coverage, or fine (145-225 μm) spray droplets which are subject to potential drift and possible negative off-target effects. - Overall, in an effort to reduce herbicide use for postemergence crabgrass control, a single quinclorac herbicide application could be properly timed and optimized with nozzles that produce spray droplets ranging from very coarse (401-500 μm) to medium (226-325 μm) in size, however, future research should consider cultural practices that would further optimize and also reduce herbicide applications.

中文翻译：

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喷嘴选择有助于改善草坪草的出苗后除草剂马唐控制

为了获得最佳的芽后马唐 (Digitaria spp.) 控制，可以适当定时施用单次喹氯酸除草剂，并使用喷嘴输送，该喷嘴产生的喷雾液滴大小从非常粗 (401-500 μm) 到中等 (226-325 μm) 到最大限度地扩大目标覆盖范围并最大限度地减少漂移的可能性。马唐是一种侵入性的一年生草本植物，生长在凉爽的季节草坪上，可作为草坪、高尔夫球场和运动场使用。在草坪草丛中用于马唐草控制的芽后除草剂应用通常依赖于重复施用来进行有效控制。优化出苗后马唐的应用可以减少农药的投入，并有助于可持续的草坪管理实践。2020 年，在肯塔基早熟禾 (Poa pratensis L. ）与俄亥俄州（美国）的多年生黑麦草（Lolium perenne L.）和宾夕法尼亚州（美国）的多年生黑麦草。这两个地点都有天然马唐草 [Digitaria sanguinalis (L.) Scop.] 侵染的历史。一种芽后除草剂，喹氯酸，以产品标签的比例施用，并在三叶一分蘖的马唐植物阶段与甲基化种子油桶混。选择不同的喷嘴以在 275 kPa 下提供以下喷雾液滴分类和尺寸：Delavan Raindrop 1/4，超粗（>650 μm）；TurfJet 1/4TTJO4，极粗（501-650 μm）；Air Induction AA8004 或 XRTeeJet 8015，非常粗（401-500 μm）；XR TeeJet 8008 或 GreenLeaf TDAD04，粗（326-400 μm）；XR TeeJet 8004，中等（226-325 μm）；和 XRTeeJet 8003 精细 (145-225 μm)。俄亥俄州的马唐压力很低，当从产生从超粗到细的喷雾液滴大小的所有喷嘴施用时，处理后 60 天的除草剂效力被认为是可以接受的。宾夕法尼亚州的马唐压力很严重，当从产生从非常粗到中等的喷雾液滴大小的喷雾喷嘴施用时，60 DAT 的除草剂功效被认为是勉强可以接受的。未来的研究应考虑与苗后除草剂应用互补的文化实践，以进一步减少农药的使用并最大限度地减少与喷雾漂移相关的任何潜在环境影响。亮点 - 在马唐压力低的草坪草场地，一种二氯喹啉除草剂的芽后施用可能通过喷嘴实现可接受的控制，该喷嘴产生从超粗（> 650 μm）到细（145-225 μm）的喷雾液滴。- 在马唐数量和压力较大的草坪草场地，最好使用可产生从非常粗（401-500 μm）到中等（226-325 μm）的喷雾液滴的喷嘴优化一种二氯喹啉除草剂的芽后施用。- 总体而言，草坪管理从业人员应避免使用产生空心锥形喷雾模式的喷嘴，该喷嘴具有超粗 (>650 μm) 喷雾液滴，这可能导致除草剂覆盖不良或不规则，或细小的 (145-225 μm) 喷雾液滴，受到潜在的漂移和可能的负面脱靶影响。- 全面的，