Aydin is the leading chestnut producing province of Turkey and supplies approximately one-third of the Turkish production. However, the nut production and the survival of the chestnut trees is under the threat of chestnut blight. So far the limited efforts applied by chestnut growers to control the disease through their own practices have been insufficient to decrease its spread and to prevent its introduction into new disease-free areas. On the contrary, the disease spread was encouraged by the sylvicultural and harvesting mistreatments. In Aydin Province out of 31 chestnut-producing villages, 22 of them were found to be contaminated with chestnut blight. Among all C. parasitica isolates obtained from the cankers of blighted trees, only one exhibited dsRNA, but its association with hypovirulence has not been established yet. Two vc types, the EU-1 and EU-12, were identified. EU-1 was the most widespread vc type. The low vc diversity provides a good potential for hypovirulence related biological control of chestnut blight in the province. In addition, the low vc diversity might be an indication of lack of sexual reproduction of C. parasitica. Mating type assays on C. parasitica isolates showed that both mating types were present in the province, however, the MAT-1: MAT-2 ratio was significantly skewed from 1: 1 in each village, which might be another evidence of lack of sexual recombination. No perithecia were encountered in nature. These results emphasize the opportunity to control the disease through biological control by introducing appropriate hypovirulent strains. But it should be remembered that in some villages of Aydin Province the presence of EU-1 and EU-12 from opposite mating types (MAT-1 and MAT-2) may create a possibility that the fungus may initiate sexual reproduction and this may result in the emergence of new vc groups.
