Crown Gall of Grapevine Caused by Allorhizobium (=Agrobacterium) vitis in Ukrain - A Survery and Meristem Micropropagation with Thermotherapy to Obtain Pathogen Free Clones

The aims of our research were: 1) to perform an extensive survey for symptoms of crown gall in vineyards in Southern Ukraine (Odesa and Mykolaiv regions), in total 2,660 ha in the period 2012-2020. Grape varieties inspected were clonal, rootstock grafted Cabernet Sauvignon, Merlot and Chardonnay; 2) detection and identification of the causal bacterium Allorhizobium vitis (All. vitis) using PCR, in samples of symptomatic and symptomless material. Sampling comprised three crown gall infested vineyards in the Odesa region (total 320ha) in 2020; 3) to free cultivar Cabernet Sauvignon clones from the pathogen via meristem micropropagation and a virus-directed thermotherapy.