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. 2020 Jan 29;10(1):1389. doi: 10.1038/s41598-020-58188-z.
Citrus black spot (CBS) caused by the fungus Phyllosticta citricarpa occurs in tropical and sub-tropical citrus production regions and affects all varieties of citrus. In Florida, the disease cycle is unique, having only the asexual spore. This work examines incidence and severity of CBS (hard spot symptoms) on fruit in two citrus groves during 2013-2014, 2014-2015 (Grove III) and 2015-2016 (Grove II) citrus seasons. Disease incidence and severity on fruit were analyzed based on citrus season, side of tree evaluated, height within the canopy, tree health, and tree age. Results indicate an increase in CBS incidence in Grove III between 2013-2014 and 2014-2015 seasons, with more infected or symptomatic fruit on the road side of the canopy and a higher incidence above 2 meters. Tree health status affected incidence but not severity and tree age had a significant effect on severity of CBS in Grove II. Analysis of weather data conducive for infection, between 2010 and 2017, indicated an average of 172 days per year (range: 104-261 days) when the temperature (15-35 °C) and relative humidity (RH ≥ 90% for 8 consecutive hours) were conducive for infection of fruit and an average of 98 days per year (range: 72-123 days) when the fruit were susceptible to infection.
柑橘黑斑病（CBS）由真菌 Phyllosticta citricarpa 引起，发生在热带和亚热带柑橘产区，影响所有柑橘品种。在佛罗里达州，该病害的生活史独特，只有无性孢子。本研究在 2013-2014、2014-2015（III 果园）和 2015-2016（II 果园）柑橘季节，调查了两个柑橘园果实上 CBS（硬斑症状）的发病率和严重度。根据柑橘季节、评估的树的一侧、树冠内的高度、树木健康和树龄，分析果实上的病害发病率和严重度。结果表明，III 果园 CBS 的发病率在 2013-2014 和 2014-2015 季节之间增加，树冠道路一侧有更多感染或有症状的果实，2 米以上的发病率更高。树木健康状况影响发病率，但不影响严重度，树龄对 II 果园 CBS 的严重度有显著影响。对有利于感染的天气数据（2010-2017 年）进行分析表明，每年平均有 172 天（范围：104-261 天）的温度（15-35°C）和相对湿度（RH≥90%，连续 8 小时）有利于果实感染，每年平均有 98 天（范围：72-123 天）的果实易受感染。
