Determination of the susceptibility levels to root rot disease of some rootstock candidates in chestnut

Although many diseases threaten chestnut cultivation, especially two diseases stand out. These diseases are chestnut blight (Cryphonectria parasitica) and root rot (Phytophthora spp.). Root rot is difficult to control because it dries out the trees. One of the most effective control methods against root rot disease is resistant rootstocks. This study was carried out in the Ondokuz Mayıs University, Faculty of Agriculture between 2019 and 2020 to determine the resistance of seedlings of some chestnut cultivars/genotypes grown in our region to Phytophthora. In the study, six-year-old seedlings of seven complex hybrid chestnut genotypes/cultivars (A9, A11, A30, A41, ‘Ali Nihat’ (A25), ‘Akyüz’ (A14), and ‘Macit 55’ (A100)), 2 European chestnut cultivars (‘Erfelek’ and ‘Salıpazarı’) and 1 Castanea crenata × C. sativa hybrid (‘Marigoule’) were used. Root rot agents Phytophthora cambivora and P. cinnamomi were inoculated on seedlings grown in pots. Disease development in inoculated plants was evaluated once a month for four months. The study used ten rootstock candidates, two root rot agents, three replications, and ten rootstocks in each replication, a total of 600 seedlings. The experiment was carried out according to the randomized plot’s design in the factorial arrangement. As a result of the study, the A9 genotype had the smallest lesion size among all genotypes. However, the lowest survival rate was obtained from the A9 genotype when the survival rates were examined. As of September 30, 2019, although there was no statistically significant difference in survival rate between genotypes, the survival rate was numerically higher in seedlings belonging to the A41 genotype. In this respect, it can be said that the seedlings belonging to the A41 genotype can be more tolerant than the other genotypes tested in the study.