| Since 2018 alarming reports on the spread of Tree-of-heaven into vineyards, fruit orchards and well as into specialised crops were received at IFFF, BOKU Vienna from Austria (Wachau, Burgenland, Southeast Styria), France (Bordeaux), Italy (Southern Tyrol) as well as from the Czech Republic, indicating the need for an effective and sustainable control of this highly invasive tree species. In viniculture there is the additional problem that Tree-of-heaven is known to serve as host for the causal agent of „flavescence dorée“, a serious phytoplasma disease of the vine. Because a sustainable biological control method of Tree-of-heaven has been developed at IFFF within the last eight years and alternative treatments (partial girdling with additional application of glyphosate into the stem) are quite costly, not always effective and might not be applicable in biological production systems, it is desirable to widen the use of our Verticillium nonalfalfae-isolate Vert56 to viniculture, pomiculture and specialised crops (e.g. cultivation of hop). However, detailed risk assessment studies have to be performed, in order to demonstrate that cultured plants are not susceptible to the wilt-fungus used for the biological control of Ailanthus (i.e. to rule out any undesired “non-target” effects). For that reason, comprehensive field inoculation studies will be carried out on the most common grapevine and fruit tree varieties grown in Austria. Studies will be conducted in close cooperation with the BOKU-Institute of Viticulture and Pomology, the School for Viticulture at Krems and the Federal College and Institute for Viticulture and Pomology Klosterneuburg, with the latter two providing the experimental plots and required experimental plants for the inoculation studies. Aim of the project is to demonstrate that even direct inoculation of the wilt pathogen into the xylem sap of the varieties to be tested does not result in the development of wilt symptoms, mortality or other non-desirable responses of the tested plants. In addition, wild apple, wild pear and nut trees, which are interesting from a forest and a nature conservation point-of-view, will be included in this study. If field inoculation studies confirm the results of our preliminary studies on the grapevine varieties “Grüner Veltliner” and “Zweigelt” in the greenhouse, isolate Vert56 might obtain general authorisation for the use in viticulture, pomiculture and specialised crops by the responsible authority AGES. |