Klein Leigh Ann, Windham Mark T, Trigiano Robert N
Graduate Research Assistant.
Associate Professor, Department of Entomology and Plant Pathology.
Plant Dis. 1998 Apr;82(4):383-385. doi: 10.1094/PDIS.1998.82.4.383.
Powdery mildew has become a common foliar disease of Cornus florida and other dogwood species in the eastern United States during the last several years. This study was conducted to determine the identity of powdery mildew fungi on C. florida and C. amomum. Ascocarps of Microsphaera pulchra and Phyllactinia guttata occurred singly and together on both C. florida and C. amomum leaves. M. pulchra ascocarps occurred at a higher density than P. guttata ascocarps on C. florida leaves, whereas P. guttata ascocarps occurred more frequently than M. pulchra ascocarps on C. amomum leaves. Histological studies, however, did not provide supplementary data of infection by the powdery mildew species that occurred less frequently on the leaves of each dogwood species. M. pulchra did not penetrate the cells of C. amomum, and likewise P. guttata did not enter through stomata of C. florida leaves. The presence of ascocarps of both species was not the result of infection of the dogwoods by both pathogens. The ascocarps of M. pulchra probably became airborne and then settled on the C. amomum leaves. Similarly, the ascocarps of P. guttata landed on C. florida leaves. These results emphasize the importance of correct pathogen identification using several criteria such as ascocarp morphology, host-pathogen relationships, distribution of the pathogen, conidial morphology, and histology.
在过去几年中，白粉病已成为美国东部多花梾木和其他山茱萸属物种常见的叶部病害。本研究旨在确定多花梾木和川鄂山茱萸上白粉病菌的种类。美丽球针壳和斑点叉丝壳的子囊果单独或同时出现在多花梾木和川鄂山茱萸的叶片上。在多花梾木叶片上，美丽球针壳子囊果的密度高于斑点叉丝壳子囊果；而在川鄂山茱萸叶片上，斑点叉丝壳子囊果出现的频率高于美丽球针壳子囊果。然而，组织学研究并未提供关于在每种山茱萸属植物叶片上出现频率较低的白粉菌种类感染情况的补充数据。美丽球针壳不穿透川鄂山茱萸的细胞，同样，斑点叉丝壳也不通过多花梾木叶片的气孔进入。两种菌子囊果的存在并非两种病原菌同时感染山茱萸属植物的结果。美丽球针壳的子囊果可能通过空气传播，然后落在川鄂山茱萸叶片上。同样，斑点叉丝壳的子囊果落在多花梾木叶片上。这些结果强调了使用多种标准（如子囊果形态、寄主 - 病原菌关系、病原菌分布、分生孢子形态和组织学）正确鉴定病原菌的重要性。
