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Etiology

Effects of Virus and Mycoplasmalike Organism Infection on Green and White Ash. Martha A. Ferris, Former graduate research assistant, Faculty of Environmental and Forest Biology, State University of New York, College of Environmental Science & Forestry, Syracuse 13210; John D. Castello(2), and Wayne A. Sinclair(3). (2)Associate professor, Faculty of Environmental and Forest Biology, State University of New York, College of Environmental Science & Forestry, Syracuse 13210; (3)Professor, Department of Plant Pathology, Cornell University, Ithaca, NY 14853. Phytopathology 79:579-583. Accepted for publication 12 December 1988. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/Phyto-79-579.

White ash (Fraxinus americana) and green ash (F. pennsylvanica) seedlings were inoculated with tobacco mosaic virus, tobacco ringspot virus (TRSV), tomato ringspot virus, and mycoplasmalike organisms (MLOs) alone and in all combinations. After three cycles of growth and dormancy, one or more pathogens was detected in 190 plants. TRSV was associated with chlorotic mottling in both species and with chlorotic spots, ringspots, and vein yellowing in green ash. Virus symptoms were more severe in green than white ash. MLOs were associated with interveinal chlorosis, dwarfing and glossiness of leaves, and production of axillary shoots. These and other symptoms have been observed in naturally infected ash. MLO, but not virus infection, was associated with suppressed growth, more so in white than in green ash. Neither synergistic nor additive effects of multiple pathogen infection on growth or symptom development in ash were detected.