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Etiology

A Stem Blight of Rose Caused by Phytophthora megasperma. Yuji Nagai, Laboratory of Plant Pathology and Entomology, Chiba Prefectural Agricultural Experiment Station, Chiba, Japan; Taeko Takeuchi(2), and Tsuneo Watanabe(3). (2)Laboratory of Plant Pathology and Entomology, Chiba Prefectural Agricultural Experiment Station, Chiba, Japan; (3)Department of Plant Pathology and Entomology, National Institute of Agricultural Sciences, Nishigahara, Kita-ku, Tokyo, Japan. Phytopathology 68:684-688. Accepted for publication 3 October 1977. Copyright © 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-684.

A stem blight of rose was first observed in Chiba Prefecture of Japan in May, 1968. Pathogenicity of Phytophthora sp. isolated from the diseased plants was proved on rose plants originating from the cuttings and grown in artificially infested soil, and on excised stems, shoots, or leaves inoculated in vitro through artificial wounds. The fungus was identified as P. megasperam on the basis of morphology. This is the first report of the natural infection of rose by P. megasperma.