First and second author: Department of Plant Pathology, Washington State University, P.O. Box 646430, Pullman 99164.
Phytopathology. 2018 Nov;108(11):1287-1298. doi: 10.1094/PHYTO-01-18-0016-R. Epub 2018 Oct 2.
Botrytis cinerea, causal agent of gray mold, is one of the most important pathogens affecting raspberry in the U.S. Pacific Northwest and worldwide. Fungicides are currently applied to control the disease starting from 5 to 10% bloom and continuing on a calendar basis throughout the season rather than according to inoculum level or infection risk primarily because the disease cycle on red raspberry is poorly understood. Botrytis cinerea was isolated from raspberry flowers and fruit sampled at seven developmental stages during each of 2015 and 2016 in a northwestern Washington raspberry field untreated with fungicides. Incidence of colonization of flowers was low (15% of total sampled flowers), but increased as fruit developed, and peaked in mature fruit (67% of total sampled fruit). In the early stages of flower development, B. cinerea recovery was greatest from the carpel (80% of carpels colonized) compared with other floral organs. As fruit matured, additional floral parts were colonized by B. cinerea, possibly facilitating secondary internal or external infections of mature fruit. Average weekly minimum air temperature, average weekly night air temperature, cumulative rain, average weekly leaf wetness percentage, and duration of leaf wetness >90% were significantly positively correlated with B. cinerea colonization of raspberry in NW Washington during two seasons of this study. Our data does not support the hypothesis that the bloom period is the critical window for B. cinerea colonization of red raspberry and suggest that later colonization of developing fruit may be more important for gray mold development on raspberry. The outcomes of this research provide useful information for improvement of gray mold disease management strategies for red raspberry in NW Washington and elsewhere.
灰霉病菌，引起灰霉病的病原菌，是美国太平洋西北地区和全球影响覆盆子的最重要病原体之一。杀菌剂目前用于控制该病，从 5%至 10%的开花期开始，然后根据日历在整个季节内持续使用，而不是根据接种体水平或感染风险进行使用，主要是因为对红覆盆子的疾病周期了解甚少。在未使用杀菌剂的西北华盛顿覆盆子田间，于 2015 年和 2016 年的每个发育阶段从覆盆子花和果实中分离出灰霉病菌。花的侵染率较低（总采样花的 15%），但随着果实的发育而增加，并在成熟果实中达到高峰（总采样果实的 67%）。在花发育的早期阶段，与其他花器官相比，从心皮（80%的心皮被侵染）中回收的灰霉病菌最多。随着果实成熟，更多的花器官被灰霉病菌侵染，可能促进成熟果实的二次内部或外部感染。在本研究的两个季节中，每周平均最低空气温度、每周平均夜间空气温度、累积降雨量、每周平均叶片湿度百分比和叶片湿度>90%的持续时间与 NW 华盛顿覆盆子中灰霉病菌的侵染呈显著正相关。我们的数据不支持开花期是灰霉病菌侵染红覆盆子的关键窗口的假设，并表明发育中果实的后期侵染可能对覆盆子灰霉病的发展更为重要。这项研究的结果为改进 NW 华盛顿和其他地区红覆盆子灰霉病管理策略提供了有用的信息。
