Abstract
Abstract A description is provided for Septoria obesa . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Chrysanthemum arcticum, C. morifolium . Also by inoculation on Chrysanthemum azaleanum, C. cinerariaefolium, C. corymbosum, C. indicum, C. koreanum, C. nivellii, C. marshallii, C. parthenium, C. rubellum, C. segetum (Punithalingam & Wheeler, 1965, Schneider, 1959). DISEASE: Brown spot of cultivated chrysanthemum (Hemmi & Nakamura, 1927). The first visible disease symptom is a small chlorotic area with a central necrotic spot that eventually enlarges to form brown or even black, circular to very irregular blotch-like lesions. These have indistinct margins and several of them may coalesce to occupy most of the leaf area. The disease is usually severe and in such cases the leaves turn yellow and subsequently wither. GEOGRAPHICAL DISTRIBUTION: Africa (Malawi, Uganda, Zambia), Asia (Ceylon. Formosa. Japan); Europe (Germany, Great Britain, Norway) and U.S.A. TRANSMISSION: According to Dimock (22: 312) the spores of the pathogen are disseminated by splashed or wind blown water or by mechanical transfer on workmen's clothing, tools and the cloth covering plants when the foliage is wet. Also the spores are said to be splashed from leaves left on the ground up to a height of 8-16 inches. The pathogen overwinters in diseased leaves left in autumn. Waddel & Weber (1963) from their viability tests with buried infected leaves concluded that the pathogen overwinters in the soil from November to April.
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