Non-target effects of Verticillium nonalfalfae isolate Vert56 used for biological control of Ailanthus altissima on agricultural crops known to be generally susceptible to Verticillium spp.

Tree of Heaven (Ailanthus altissima), a tree species native to China, was introduced into Europe as an ornamental plant about 250 years ago. It is known for its invasive spread with negative impacts on natural ecosystems as well as human infrastructure. Its control is inevitable in some areas, e.g. transportation corridors, for safety reasons. Furthermore, management actions are mandatory according to EU legislation, but common strategies are time-consuming, costly, only moderately effective and, in case of herbicide treatments, controversially discussed due to environmental issues. Isolate Vert56 of the vascular wilt fungus Verticillium nonalfalfae has been proven in previous studies to be highly adapted and highly virulent to Ailanthus, while inoculation of potentially suscep-tible tree species with this isolate showed no evidence of negative non-target effects. This study focused on non-target effects of isolate Vert56 on agricultural crops known to be generally sus-ceptible to Verticillium spp. In a greenhouse experiment, seedlings of seven different species (including Ailanthus as a positive control) were artificially inoculated via root dipping or, in the case of seedlings of two potato varieties, by direct addition of the inoculum into the pot.

Automated summary

Tree of Heaven, an invasive species, has negative impacts on natural ecosystems and human infrastructure. Previous studies have identified a strain of fungus that is highly effective against the tree without negative effects on other plants. This study focuses on the non-target effects of this strain on susceptible agricultural crops.