<i>Cladosporium</i> Species: The Predominant Species Present on Raspberries from the U.K. and Spain and Their Ability to Cause Skin and Stigmata Infections

Raspberry (<i>Rosales</i>: <i>Rosaceae</i>) production in the U.K. has moved rapidly in the last 10 years to under polythene, combined with a reduced availability of broad-spectrum fungicides. Hence, the incidence of previously less prevalent diseases, such as <i>Cladosporium</i> (<i>Capnodiales: Cladosporiaceae</i>), has largely increased. This study aimed to identify the predominant <i>Cladosporium</i> species on raspberry and to understand the nature of its infection on raspberry fruit. Raspberries were collected from farms across the U.K. and Spain and incubated; fungal isolates were then isolated from typical <i>Cladosporium</i> lesions and identified to the species level based on the sequences of the trans elongation factor α and actin genes. <i>Cladosporium cladosporioides</i> (Fres) de Vries was confirmed as the predominant species responsible for infecting raspberry fruit close to harvest on fruit from the U.K. and Spain, being present on 41.5% of U.K. fruit and 84.6% of Spanish fruit. Raspberries were subsequently inoculated at different developmental stages with <i>C. cladosporioides</i> isolates to determine the susceptibility to <i>Cladosporium</i> skin lesions and stigmata infections in relation to the developmental stage. Only the ripening and ripe raspberries were susceptible to <i>Cladosporium</i>, resulting in skin lesions. <i>Cladosporium</i> can colonise the stigmata of raspberries earlier in fruit development and future research is required to determine if such stigmata infections could cause subsequent skin lesion infections. This study has provided the necessary epidemiological information to develop effective management measures against the <i>Cladosporium</i> species.