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Ecology and Epidemiology

Infection of European Hazelnut by Anisogramma anomala: Site of Infection and Effect of Host Developmental Stage. K. B. Johnson,Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 92331-2902; J. N. Pinkerton(2), S. M. Gaudreault(3), and J. K. Stone(4). (2)USDA ARS Horticultural Crops Research Laboratory, Corvallis, OR 97330; (3)(4)Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 92331-2902. Phytopathology 84:1465-1470. Accepted for publication 13 September 1994. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1994. DOI: 10.1094/Phyto-84-1465.

The concentration of ascospores of Anisogramma anomala required to infect 50% of spray-inoculated shoots of European hazelnut (Corylus avellana) was 7 × 10⁴ and 2 × 10⁵ spores per milliliter for seedlings of cvs. Ennis and Royal, respectively. Placement of A. anomala ascospores (5 × 10⁶ per milliliter) on the shoot internode immediately below the apical meristem resulted in 79% infection of inoculated seedlings. In contrast, ascospores applied onto the second, third, or fourth shoot internode below the meristem resulted in 32, 9, and 6% infection of seedlings, respectively. Similarly, incidence of infection after inoculation of the expanding leaf nearest the apical meristem averaged 64%, but only 19, 7, and 2% when ascospores were applied onto the second, third, or fourth leaf from the meristem, respectively. Ascospores spray-inoculated (1 × 10⁵ spores per milliliter) onto vegetative buds and shoots at various stages of development resulted in infection of 0% of dormant buds, 63% of buds with leaf tips emerged, 79% of buds with a full leaf emerged, 88% of elongating shoots with two to four nodes, 29% of elongating shoots with eight to ten nodes, and 0% of shoots that had stopped adding new growth late in the season. Hazelnut buds infested with an eriophyid bud mite, Phytoptus avellanae, were not more susceptible to infection by A. anomala than noninfested buds as had been reported previously.