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Oral: Fungal Diseases


Identifying sources of inoculum and timing of tissue infection by fungal pathogens associated with winterberry fruit rot
F. PEDUTO HAND (1), S. Lin (1), N. Taylor (1) (1) The Ohio State University, U.S.A.

Winterberry is a valuable deciduous ornamental plant carrying brightly colored berries during the winter that is popular as a cut green for use in holiday decorations. In the past 3-4 years, a fruit rot has been challenging winterberry growers in the midwestern and eastern U.S., in some cases leading to complete crop loss. In this study, we monitored winterberry 'Bonfire' and 'Sparkleberry' throughout the 2015 growing cycle in two Ohio nurseries to identify sources of inoculum and assess periods of tissue infection. Twigs and mummified fruit were collected during plant dormancy to determine potential sources of primary inoculum. Flowers, leaves, and berries were collected weekly from June to December to record leaf spot and fruit rot incidence and severity, as well as pathogen recovery. Spore traps were used during the growing season to monitor spore abundance in the orchards. Based on the isolation results as well as counts from the spore traps, it appears that the disease may be due to a fungal complex, including species of Alternaria, Cladosporium, Colletotrichum, Epicoccum, Fusarium, Phoma, and Phomopsis. The major source of primary inoculum appears to be the mummified fruit. Leaf spots may serve as a source of secondary inoculum. A significant increase in the number of fungi recovered at bloom indicates that flowers could serve as a point of entry for fruit infections. The ultimate goal of this study is to provide growers with appropriate management strategies.