Volume: 50 Host publication title: 6th International Plant Protection Symposium at University of Debrecen Proceeding volume: 50 European mistletoe (Viscum album), the hemiparasitic shrub, infects a wide range of woody species. It adversely affects the height and diameter growth and it is associated with increased mortality of its hosts. Currently there are no effective control methods against it. Therefor, we started to study a specific hyperparasitic fungus (Phaeobotryosphaeria visci), which can completely destroy European mistletoe by infecting its branches, leaves and berries. An important aspect of the initial phase of mycopesticide candidate is culturing of the organism on artificial or non-synthetic media, followed by the optimization of spore production. We focused to determinate the growth media and light conditions needed for sporulation of P. visci. We also tested the viability and pathogenecy of the spores, because these are important features for further processing and applications. The cultures were grown on seven different media (potato dextrose agar, sugar free potato dextrose agar, cellophane covered potato dextrose agar, oatmeal agar, V8 Juice agar, S medium and SNA medium) under constant dark, constant light (400-750 nm) and 12 h of alternating dark and light illumination. The best primary agar media were oatmeal and sugar free potato dextrose agar under permanent illumination, while constant dark inhibited the conidial production. The viability and virulence of harvested conidia were normal, and the symptoms of the disease appeared 7-14 days after the inoculation on mistletoe leaves. We will continue our experiments studying the effect of near UV (280–400 nm) light. Use of variable photoperiods supplemented with near UV and different media could help us to optimize the spore production and create a fast and cheap mass production technique.
