Number of cores per citrus tree (sample size) needed to estimate the citrus nematode count (second-stage juveniles and males) in the soil was investigated. Coefficient of variation of mean (CV) was used as a measure of reliability and Taylor's power law model was used as a descriptor of nematode spatial distribution. The study was replicated twice during early winters 2018 and 2019 in two citrus orchards of Fars province, southern Iran. For each of the six selected trees, 10 cores (10–15 cm in diameter × 30 cm in depth) were systematically sampled from beneath each tree canopy; six and four cores from the outer and inner parts of irrigation dripline, respectively. Second-stage juveniles (J2s) and males of the nematode in soil were extracted using a Bearman tray method for 48 h. Besides 10 single samples from each core, the sampling patterns were designated in two forms of real and virtual compositions. Real compositions included of an average of two or three composite samples from outer and/or inner part of irrigation dripline. The virtual compositions corresponded to the real compositions and were formed by combining nematode count data rather than soil samples. Parameters of Taylor's power law model were estimated by fitting the model to the data and used for sample size calculations for this nematode. The results of the two trials revealed that in terms of reliability, and cost an average of two composite samples from the outer (six cores) and inner (four cores) areas of the irrigation dripline could be recommended as the best sampling plan for estimating the nematode population in infested orchards.

研究了估计土壤中柑橘线虫数量（第二阶段的幼虫和雄性）所需的每棵柑橘树的核心数（样本大小）。均值变异系数（CV）用作可靠性的量度，泰勒幂定律模型用作线虫空间分布的描述子。这项研究在2018年初和2019初冬在伊朗南部法尔斯省的两个柑橘园中进行了两次重复。对于六棵选定的树木中的每棵，从每个树冠下面系统地取样10个岩心（直径10–15厘米×深度30厘米）。灌溉滴灌线的外部和内部分别有六个和四个岩心。使用Bearman托盘法提取土壤中线虫的第二阶段幼虫（J2s）和雄性，持续48 h。除了每个核心10个单个样本之外，采样模式以真实和虚拟构图两种形式指定。实际成分包括平均两个或三个来自灌溉滴灌线外部和/或内部的复合样品。虚拟成分对应于真实成分，是通过组合线虫计数数据而不是土壤样品形成的。通过将模型拟合到数据中来估计泰勒幂律模型的参数，并将其用于此线虫的样本量计算。两项试验的结果表明，就可靠性和成本而言，可以推荐使用灌溉滴灌线外部（六个岩心）和内部（四个岩心）区域的两个复合样本的平均值作为估算样本的最佳采样方案。受侵染的果园中的线虫种群。