Untersuchungen zur Verticillium-Welke im Hopfenanbaugebiet Hallertau

Verticillium wilt is a devastating disease in hops and causes considerable crop losses. V. albo-atrum is the most widespread species, whereas V. dahliae is rarely found. Due to the survival of the fungus for several years in soil by resting structures and the lack of effective chemical control, a fast detection method is needed. One aim of this study was to evaluate the occurrence of Verticillium spp. in the Hallertau region (Germany). Therefore, 76 hop plants, with or without wilt symptoms, were analyzed using a real time PCR (polymerase chain reaction) assay. V. albo-atrum was identified in 57 bine samples. The pathogen can sporadically appear without showing visual symptoms. The abundance of the fungus inside the plants was analyzed. Furthermore, four beneficial bacteria, Burkholderia terricola ZR2-12, Pseudomonas poae RE*1-1-14, Serratia plymuthica 3Re4-18, and Stenotrophomonas rhizophila DSM14405T, were evaluated as biological control agents in hops. The colonization competence in the root system, plant growing promotion, and antagonistic effects were assessed. All strains colonized the endorhiza and the rhizosphere. The bacterial strains B. terricola ZR2-12, S. plymuthica 3Re4-18, and S. rhizophila DSM14405T are promising candidates for further biocontrol strategies. Thus, first steps towards the biological control of Verticillium wilt were presented.