Infection of European Hazelnut byAnisogramma anomala:Site of Infection and Effect of Host Developmental Stage

The concentration of ascospores of Anisogramma anomala required to infect 50% of spray-inoculated shoots of European hazelnut (Corylus avellana) was 7 × 10 4 and 2 × 10 5 spores per milliliter for seedlings of cvs. Ennis and Royal, respectively. Placement of A. anomala ascospores (5 × 10 6 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 × 10 5 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