Environmental Conditions Required for Infection of Photinia Leaves by Entomosporium mespili. A. B. A. M. Baudoin, Assistant Professor, Department of Plant Pathology, Physiology and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg 24061. Plant Dis. 70: 519-521. Accepted for publication 27 December 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-519.

The optimum temperature for infection of photinia leaves by Entomosporium mespili was about 20 C, and infection was only slightly retarded at 15 and 25 C. Very little infection occurred at 30 C. Leaf wetness for 9–12 hr was required for substantial infection, although leaf wetness as brief as 5–6 hr sometimes produced a few leaf spots at the optimum temperature. After deposition onto leaves, conidia survived dry periods of 12 hr at 25 C in darkness or outdoors in the shade with little loss of infectivity, regardless of whether the dry period occurred immediately after inoculation or after 5 or 12 hr of leaf wetness. Only bright sun and high temperature resulted in a significant loss of infectivity.

Keyword(s): Diplocarpon maculatum, Entomosporium maculatum, Fabraea maculata, Photinia × fraseri.