VIEW ARTICLE

Ecology and Epidemiology

Effect of Radiation, Temperature, and Moisture on Conidial Germination of Alternaria solani. R. E. Stevenson, Research assistant, Department of Plant Pathology, The Pennsylvania State University, University Park 16802; S. P. Pennypacker, Associate professor, Department of Plant Pathology, The Pennsylvania State University, University Park 16802. Phytopathology 78:926-930. Accepted for publication 27 January 1988. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/Phyto-78-926.

Conidia of Alternaria solani germinated only when the measured relative humidity (RH) was ≥ 92% and free moisture encompassed the conidia. When maintained under controlled temperature and moisture conditions, conidia germinated most rapidily in darkness when ambient temperature was near 25 C and RH ≥ 96%. For conidia irradiated with simulated sunlight (>300 nm), inhibition of germination increased as light intensity increased. Light between 300–500 nm appeared to be responsible for the inhibition in germination. Wavelengths >750 nm did not inhibit germination, indicating that inhibition was a true light phenomenon, not a response to increased temperature.