Olson H A, Benson D M
Department of Plant Pathology, North Carolina State University, Raleigh 27695.
Plant Dis. 2013 Jan;97(1):74-80. doi: 10.1094/PDIS-02-12-0170-RE.
Three isolates of Phytophthora cryptogea and three isolates of P. drechsleri were evaluated for host specificity and variations in aggressiveness on eight floriculture crops commonly grown in North Carolina. Plants were monitored for the development of foliar symptoms stemming from root rot caused by Phytophthora. No isolates of P. cryptogea or P. drechsleri had the same host range, though all P. cryptogea isolates caused foliar symptoms on gerbera daisy and annual stock, and all P. drechsleri isolates incited disease on osteospermum. No African marigold plants developed foliar symptoms of Phytophthora root rot. All P. cryptogea isolates caused foliar symptoms on at least three tested plant species. Isolates of P. drechsleri varied from highly specific and only causing disease on a single host species to relatively nonspecific and causing foliar symptoms on the majority of host plants. This is the first report of host specificity of ornamental isolates of P. drechsleri, and several of the tested plants are not reported hosts of P. drechsleri. Differences in isolate aggressiveness were found and depended on plant species; overall, isolates of P. drechsleri were more aggressive than P. cryptogea isolates. Isolations from nonsymptomatic inoculated plants suggest that these Phytophthora spp. could be moved between growers or from growers to consumers on nonsymptomatic infected ornamentals.
对三种隐地疫霉分离株和三种德氏疫霉分离株进行了寄主特异性评估，以及它们对北卡罗来纳州常见种植的八种花卉作物的致病力差异评估。监测植物因疫霉引起的根腐病而产生的叶部症状发展情况。虽然所有隐地疫霉分离株都在非洲菊和一年生紫罗兰上引起叶部症状，且所有德氏疫霉分离株都在蓝目菊上引发病害，但没有一种隐地疫霉或德氏疫霉分离株具有相同的寄主范围。没有非洲万寿菊植株出现疫霉根腐病的叶部症状。所有隐地疫霉分离株至少在三种测试植物物种上引起叶部症状。德氏疫霉分离株的致病情况各不相同，从高度特异性且仅在单一寄主物种上致病到相对非特异性且在大多数寄主植物上引起叶部症状。这是关于德氏疫霉观赏分离株寄主特异性的首次报道，并且一些测试植物并未被报道为德氏疫霉的寄主。发现了分离株致病力的差异，且这种差异取决于植物物种；总体而言，德氏疫霉分离株比隐地疫霉分离株更具致病力。从无症状接种植物中分离出病菌表明，这些疫霉属物种可能通过无症状感染的观赏植物在种植者之间或从种植者传播到消费者手中。
