Investigation of Agents Causing Fungal Wilt of Seabuckthorn in West Siberia

A.S. Smirnov, E.M. Shaldyaeva., V.M. Chekurov, V.K. Kreimer, A.V. Smorodin, and E.F.Mikhalevich

The problem of seabuckthorn resistance against detrimental environmental factors becomes increasingly important because of the wide introduction of this crop. Combined interaction of these factors causes its fungal wilt. The most important factors of biotic control in Siberia are fungal infections, which attack the root and vascular systems and cause fungal wilt of the trees. Fungal wilt of seabuckthorn caused by fungal agents can be acute or chronic.

In 2002, we studied the range of species that cause fungal wilt of seabuckthorn in the forest-steppe zone of West Siberia and their organ and developmental specificity. The microorganisms were isolated from interior tissues by conventional methods. Tissue samples were taken from various organs of trees: branches of various ages, wood from the trunk and basal parts, and parts of the root system. It was found that disease is caused mainly by species of three genera: Verticillium, Fusarium, and Alternaria. The acute disease was caused by Verticillium and Fusarium to the same extent. In our experiments we often isolated mixtures of species of these genera, which caused mixed infections and were sometimes accompanied by Alternaria. Fungi of the genera Verticillium and Fusarium showed no clear organ specificity and were isolated from all organs mentioned, whereas the genus Alternaria was isolated mainly from branches of various ages or, less often, from basal organs. Fungi of the genus Alternaria were most often.