Survey on diseases and fungal pathogens associated with cankers and decline of sea buckthorn

Abstract: Common sea buckthorn (Hippophae rhamnoides L.) is a deciduous shrub (family Elaeagnaceae) used for centuries in medicine, cosmetics and food. In several European countries, it is an indigenous species and nowadays a commercially important cultivated fruit crop in northern temperate regions of Europe, Asia and North America. However, the sea buckthorn diseases and pests are not widely studied and plant health problems are still not efficiently addressed. The sea buckthorn diseases and their causal agents have been worldwide poorly studied, limited to only a few records of stem canker, wilt and dry shrink diseases caused by Stigmina sp., Verticillium spp., and Fusarium spp., respectively. In Latvia, the sea buckthorn cultivation is rapidly expanding. To identify and characterise fungal diseases of sea buckthorn, 58 locations including commercial orchards and wild habitats were surveyed. The samples from branches, roots, and trunks with various disease symptoms were collected. Fungi were isolated from surface sterilised plant tissues on potato dextrose agar, sub-cultured in pure cultures and preserved for further studies. The isolated fungi were identified by morphological characters and sequencing. During the surveys, overall decline, wilt, severe canker and dieback symptoms often causing the death of the plants were observed. The majority of fungi obtained from the diseased tissues were identified as belonging to genera of Diaporthe, Eutypa, Fusarium, and Verticillium. The pathogenicity evaluation of the selected fungal isolates on sea buckthorn plants in the greenhouse is currently in progress.