Cadophora luteo-olivacea on apple and kiwifruit: characterization of selected strains and evaluation of fungicides for their control

Cadophora luteo-olivacea has been reported as an emerging postharvest pathogen of pome fruit and kiwifruit with the potential to have a significant economic impact. To date, the biology and epidemiology of C. luteo-olivacea has been poorly investigated. Therefore, the present study aims to gain knowledge on C. luteo-olivacea biology, by analyzing the parameters that can influence the fungal growth and virulence and by getting information about the sensitivity to fungicides. A mycelial growth study at different temperatures was conducted with five C. luteo-olivacea isolates belonging to different host plants (apple and kiwifruit). The optimum fungal growth was observed in a temperature range between 20 °C and 25 °C, with C. luteo-olivacea isolates from kiwifruit that resulted in faster growth than apple isolates. The pathogenicity of C. luteo-olivacea isolates was evaluated on detached apple and kiwifruit twigs, on 'Golden Delicious' and 'Fuji' apples, and on 'Hayward' and 'Sungold' kiwifruit, stored both at 0 °C and 20 °C. The pathogenicity on fruit and on woody twigs was variable, depending on the host cultivar, with a minor effect related to the fungal isolate. Moreover, the efficacy of ten different plant protection products (PPPs) against the conidial germination of the isolates was determined. Few PPPs were found to be effective (e.g. fludioxonil, dithianon, and cyprodinil) against C. luteo-olivacea. These results represent a starting point for further research on the biology and epidemiology of C. luteo-olivacea and the development of effective management strategies.