Characterization and pathogenicity of Bulgarian isolates Phytophthora chlamydospora on ornamental plant species

Petya K. Christova

Abstract: Phytophthora chlamydospora belongs to clade 6 of the genus Phytophthora and is one of the most common species of the genus in the aquatic environment. In the collection of the genus Phytophthora established at the AgrobioInstitute, the species is represented by several isolates, two of which are the subject of this study. The isolates P. chlamydospora RChOs2016/83b and RChVitTet2017/102b, originating from the rivers Cherni Osam and Cherni Vit, respectively, are characterized by petaloid growth on carrot agar, whereas on potato agar they form rosaceous colonies. The two isolates demonstrate radial growth rate on CA in temperature range from 5 to 30°C with temperature optimum at 20°C. The investigated P. chlamydospora isolates causes similar symptoms on inoculated leaves of wild common peony, rose and hydrangea, but differ in their aggressiveness against leaves of cherry laurel, as the isolate RChVitTet2017/102b induces more severe necrosis then the isolate RChOs2016/83b. In addition to infection of leaves, the results of further analyses confirm the ability of the two Bulgarian isolates P. chlamydospora to infect cutting of wild hydrangea and cherry laurel. Both isolates have been identified as potentially dangerous pathogens for ornamental plant species grown in nurseries, parks, gardens and also in their natural habitats.

Keywords: cherry laurel; clade 6; common peony; Phytophthora; rose; wild hydrangea

Date published: 2020-03-10