Dollar spot (Clarireedia jacksonii) susceptibility varies among bentgrasses (Agrostis spp.). This trial assessed the ability of five action thresholds of the risk index (RI) of a logistic regression model to forecast dollar spot incidence on bentgrass fairway turf grown on a sandy loam in North Brunswick, NJ. Dollar spot incidence was assessed over 128 observation periods (May to Nov. annually) over 3 yr and related to five action thresholds for prediction accuracy. Action thresholds included a RI threshold of 20% (RI 20%), interpreting the change in the RI over time (RI slope), adjusting the RI upwards to maximize accuracy (RI_max), combining RI 20% with RI slope, and combining RI_max with RI slope. The RI 20% accurately predicted disease on 63 to 66% of observation periods for highly susceptible creeping bentgrass (A. stolonifera L.) cultivars Shark, Penncross, and Independence; other action thresholds improved accuracy by only 10% or less for these cultivars. Prediction accuracy on lower susceptibility cultivars (007, Declaration, and colonial bentgrass Capri; A. capillaris L.) was substantially improved with four novel action thresholds by reducing over-predictions compared to RI 20%. Accuracy was improved by as much as 32% when the RI_max and RI slope were combined for Declaration compared to RI 20%. On low susceptibility cultivars, turf managers may be able to use action thresholds that incorporate a RI greater than 20% and/or RI slope to reduce fungicide inputs and maintain acceptable dollar spot control compared to RI 20%.

中文翻译：

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逻辑回归模型的新动作阈值预测翦股颖上的美元斑点

美元斑病( Clarireedia jacksonii ) 对绦虫( Agrostis spp.) 的敏感性不同。该试验评估了逻辑回归模型的风险指数 (RI) 的五个动作阈值对预测新泽西州北布伦瑞克沙壤土上生长的翦股颖球道草皮上的美元斑点发生率的能力。美元现货发生率在 3 年的 128 个观察期（每年 5 月至 11 月）进行评估，并与预测准确性的五个行动阈值相关。动作阈值包括 20% (RI 20%) 的 RI 阈值、解释 RI 随时间的变化（RI 斜率）、向上调整 RI 以最大限度地提高准确性（RI _max）、将 RI 20% 与 RI 斜率相结合，以及结合RI_最大值与 RI 斜率。对于高度易感的匍匐翦股颖 ( A. stolonifera L.) 品种 Shark、Penncross 和 Independence，RI 20% 准确预测了 63% 至 66% 的观察期的疾病；对于这些品种，其他动作阈值仅将准确性提高了 10% 或更少。与 RI 20% 相比，通过减少过度预测，通过四个新的行动阈值大大提高了对较低易感性品种（007、Declaration 和群落翦股颖；A.capillary L.）的预测准确性。当 RI_最大时，精度提高了 32%与 RI 20% 相比，声明和 RI 斜率结合在一起。在低敏感性品种上，草坪管理者可能能够使用包含大于 20% 的 RI 和/或 RI 斜率的行动阈值，以减少杀菌剂的投入并保持可接受的美元现货控制（与 RI 20% 相比）。