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Susceptibility of selected ornamental plants to Phytophthora ramorum

Informally Refereed
Download (PDF 132 KB): https://research.fs.usda.gov/download/treesearch/30340.pdf

Abstract

Within the European project ?Risk Analysis for Phytophthora ramorum? (RAPRA), susceptibility of economically and ecologically important plants in Europe towards P. ramorum was tested via in vitro inoculation methods. In these studies different species and/or cultivars of Buxus, Calluna, Erica, Hedera, Rhododendron, and Vaccinium were tested using a detached leaf or twig assay. Zoospore suspensions of five isolates, three European and two North American, were produced for inoculation by immersion of detached leaves and twigs, some of which had been wounded prior to the treatment. After incubation in a wet chamber, development of necrosis was measured.

In these in vitro tests all Buxus spp., Hedera helix, Vaccinium corymbosum and V. macrocarpon were classified as not susceptible. Rhododendron simsii and Erica x darleyensis developed only small necroses and were classified as slightly susceptible, the susceptibility of R. simsii varying with the cultivar. The cultivar ?Desta? was the most susceptible of the four cultivars tested. Erica cinerea was classified as moderately susceptible and E. gracilis, E. carnea, Calluna vulgaris, Vaccinium myrtillus and V. oxycoccus as highly susceptible. The cultivar ?Marleen? of C. vulgaris was significantly less susceptible than the three other cultivars.

Whether or not the plants had been wounded before inoculation was often irrelevant, though wounding did lead to larger necroses for some of the plant species, e. g. R. simsii, V. oxycoccus, and V. corymbosum. The aggressiveness of the isolates varied with the plant species tested.

Parent Publication

Citation

Kaminski, K.; Wagner, S.; Werres, S. 2008. Susceptibility of selected ornamental plants to Phytophthora ramorum. In: Frankel, Susan J.; Kliejunas, John T.; Palmieri, Katharine M., tech. coords. 2008. Proceedings of the sudden oak death third science symposium. Gen. Tech. Rep. PSW-GTR-214. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. p. 1