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Action thresholds for summer fungicide sprays and sequential classification of apple scab incidence.

机译：夏季杀菌剂喷雾的作用阈值和苹果黑星病发病率的顺序分类。

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The objectives of this study were to establish scab incidence thresholds at which summer fungicide sprays should be initiated and to develop sequential sampling for classification plans to facilitate decision making. The relationship between proportion of scabbed leaves per shoot and percent scabbed fruits at harvest was established based on data collected in both experimental and commercial orchards. Action threshold at which fungicide spray program should be initiated in order to maintain fruit scab at harvest below 2% was established at 0.006 scabbed leaves per shoot; hence incidence thresholds of 0.005 and 0.01 scabbed leaves per shoot were evaluated. Sequential sampling for classification procedures (SSCP), using the Wald's sequential probability ratio test (SPRT), were developed based on a beta-binomial distribution and using parameter estimates of the binary power law. Monte Carlo simulations were used to establish the probability of classifying mean scab incidence as less than the action thresholds (pth=0.005 and pth=0.01). Operating characteristic (OC) and average sample number (ASN) curves were established for eight combinations of stop lines and error levels ( alpha and beta ). Based on the results of the Monte Carlo simulations, four sets of stop lines (two for each pth threshold) were selected for further evaluation. Bootstrap simulations of 50 data sets indicated that both the OC and ASN curves for each of the four pairs of stop lines were similar to OC and ASN values determined by Monte Carlo simulation. When validated with data not used to construct the models, the SSCPs provided the appropriate classification in 98 and 95% of the simulations for the pth=0.005 and pth=0.01 ( alpha =0.05 and beta =0.10), respectively. The sequential sampling plans developed in this study should allow for rapid and accurate classification of the incidence of apple scab on leaves, and aid in sampling for summer scab management decision making.
机译：这项研究的目的是确定应开始夏季杀真菌剂喷雾的ab疮发病阈值，并为分类计划制定顺序采样以促进决策。基于在实验和商业果园中收集的数据，建立了每枝sc叶片的比例与收获时sc果实百分比之间的关系。为使收获时果实结sc保持在2％以下而应启动杀真菌剂喷洒程序的行动阈值确定为每枝0.006片刺伤叶片;因此，评估了每枝0.005和0.01 sc叶的发病阈值。基于Walter的顺序概率比率检验（SPRT），基于β-二项式分布并使用二进制幂定律的参数估计值，开发了分类程序的顺序采样（SSCP）。蒙特卡罗模拟用于建立将平均结incidence发病率分类为小于动作阈值（ pth = 0.005和 pth = 0.01）的概率。针对停止线和错误级别（alpha和beta）的八种组合，建立了操作特征（OC）和平均样本数量（ASN）曲线。根据蒙特卡洛模拟的结果，选择了四组停止线（每个 pth 阈值两套）进行进一步评估。对50个数据集的Bootstrap仿真表明，四对停止线中每条的OC和ASN曲线都类似于由蒙特卡洛仿真确定的OC和ASN值。当使用未用于构建模型的数据进行验证时，SSCP在98％和95％的模拟中为 pth = 0.005和 pth = 0.01（alpha = 0.05和beta = 0.10）。在这项研究中制定的顺序采样计划应允许对苹果黑星病在叶子上的发生率进行快速，准确的分类，并有助于进行夏天黑星病管理决策的采样。

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