University of Florida, IFAS-Southwest Florida Research and Education Center, Department of Plant Pathology, Immokalee, FL, 34142, USA.
University of Florida, Department of Statistics, Gainesville, Florida, 32611, USA.
Sci Rep. 2017 May 9;7(1):1641. doi: 10.1038/s41598-017-01901-2.
Citrus black spot (CBS) caused by Phyllosticta citricarpa, is the most recent introduction of an exotic citrus pathogen into Florida and has been a challenge to control to date. Understanding the dispersal pattern of the disease within affected groves is vital in developing effective control strategies to limit the spread of the disease. The spatial pattern of CBS-affected trees was studied in two commercial 'Valencia' orange groves over three consecutive citrus seasons. Cluster analyses based on nearest-neighbor distance (F, G and J-functions) and pairwise distances between points (Ripley's K function, Besag's L function and the pair correlation function, g) were used to test the hypothesis of complete spatial randomness (CSR) of CBS infected trees within the groves. In both groves, the hypothesis of CSR was rejected for all tests performed including quadrats testing (2 × 2 trees up to 10 × 10 trees). The relationship between tree age and disease was assessed at one experimental site. Citrus trees bearing fruit for the first time accounted for approximately 13% of trees positive for disease and were located within areas of heavy disease pressure. These findings support short distance movement of inoculum as the main spread of disease in the groves studied.
由 Phyllosticta citricarpa 引起的柑橘黑斑病（CBS）是最近传入佛罗里达州的外来柑橘病原体，迄今为止一直是控制该病的挑战。了解受影响果园内该病的传播模式对于制定有效的控制策略以限制该病的传播至关重要。在三个连续的柑橘季节中，对两个商业“ Valencia”橙园的 CBS 感染树木的空间格局进行了研究。基于最近邻距离（F、G 和 J 函数）和点之间的成对距离（Ripley 的 K 函数、Besag 的 L 函数和对相关函数 g）的聚类分析用于检验果园内 CBS 感染树木完全空间随机性（CSR）的假设。在两个果园中，所有进行的测试（包括 2×2 树到 10×10 树的四分体测试）都拒绝了 CSR 的假设。在一个实验地点评估了树龄与疾病的关系。首次结果的柑橘树约占阳性树的 13%，并位于疾病压力大的区域。这些发现支持了接种体的短距离传播是研究中果园疾病传播的主要途径。
