Promising Results on Biological Control of Chestnut Blight in Tur

In this study, results of studies about the biological control of chestnut canker with hypovirulent strains during 2002-2005 and natural dissemination of hypovirulence in the same chestnut stand during 2007-2008 in Manisa – Hacıisalar village in Turkey were reported. During the field and laboratory studies only virulent Cryphonectria parasitica isolates were obtained from the infected trees belonging to EU-1 vc-group and MAT1-1 mating type. During the conversion tests, hypovirulence could be tranmitted to all of these isolates by the local hypovirulent strain coded as HiSF1, which also belonged to vc type EU-1 and MAT1-1 mating type. Following this result, HiSF1 was inoculated onto cankered tissues of the infected trees, after measuring the length and width of the tissue and the changes in the dimensions of infected area were measured monthly. It was recorded that most of the active cankers treated with the HiSF were becoming smaller by forming callus tissue and some others were changing from active growing type to healed-superficial cankers. HiSF was re-isolated from both of those healing canker types. After completion of this study, the research area was visited at certain intervals in order to follow the canker development on the trees, and four years after inoculation, in 2007-2008, new healing cankers were recorded on inoculated as well as on non-inoculated trees, indicating that hypovirulence could spread naturally in the chestnut grove.