Infection of raspberry leaves by Botrytis cinerea in relation to leaf and cane age

Botrytis cinerea Pers, ex Fr. can cause diseases on both cane and fruit on raspberry. Previous observations in field crops led to formulation of the hypothesis that infection of canes arose from invasion by mycelium from the petioles of infected leaves and that only mature and old leaves are susceptible. Inoculation studies in protected crops were conducted to investigate infection of raspberry leaves and canes by B. cinerea with a particular emphasis on determining the timing of cane infection in relation to leaf infection. The results obtained in protected crops indicated that cane age rather than the leaf age per se influences the susceptibility of leaves; leaves on young canes were less susceptible to botrytis infection than those on old canes. On older canes, leaves of all ages, ranging from young expanding to old senescent, were equally susceptible. The overall incidence of cane infection from inoculation of leaves was very low; most of cane infection was likely to have resulted from the direct infection of canes and not through invasion via the petioles of infected leaves.