Disease Note

Botryodiplodia Blight of Rose in India. A. Arya, Department of Botany, University of Allahabad, Allahabad 211002, India. R. C. Srivastava, and B. Lal, Department of Botany, University of Allahabad, Allahabad 211002, India. Plant Dis. 69:726. Accepted for publication 11 December 1984. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-726c.

During a survey of foliicolous fungi in the gardens of Allahabad and adjacent areas in India, an unrecorded leaf spot disease of rose (Rosa indica L.) was observed during the monsoon months of July–October 1980. The pathogen was identified as Botryodiplodia jaczevskii Negru (IMI 256487) on the basis of morphological characteristics (pycnidia: stromatic, globose, black, 700–900 μm diam; conidia: globose to ovoid, one-celled hyaline or two-celled dark brown, 16.8 [11.1–24.4] × 13.3 μm [11.1–14.5 μm]; hyphae: brown, 2.2–4.4 μm diam). Leaf spots were amphigenous, distinct, circular to irregular, and buff-brown, eventually changing to drab cinnamon. Spots were generally initiated along the margins and tips of the leaflets and eventually covered most of the surface. Infected leaflets became chlorotic and detached from the leaves. The fungus was responsible for severe defoliation. On heavily infected plants, twigs also showed symptoms. Pathogenicity tests were conducted with the fungus and Koch’s postulates were fully satisfied. Young, uninjured leaves were more susceptible than older uninjured leaves.