Assessing the relationship between some environmental variables and spread of charcoal disease on chestnut-leaved oak (Quercus castaneifolia CA Mey)

Outbreak of charcoal disease caused by Biscogniauxia mediterranea (De Not.) Kuntze، have occurred periodically in oak forests of Iran in recent years. This study was performed to investigate the relationship between some environmental variables and charcoal epidemic disease during the years 2013 - 2014 at chestnut leaved oak trees in the national park of Qoroq in Golestan province. For this purpose، the health status of 385 trees were examined in seven transects with 102 nodes. The results showed that 25. 8، 14. 4 and 59. 8 percent of the selected trees were not infected، completely dried or with different infection levels، respectively. The infection rate and severity of the damage increased more in the old trees than the young; however، the mortality rate was higher than in the young trees. Overall، the mortality rate and infection of the oak trees in the study area were 49. 5 and 1. 5 percent per year، respectively. The results showed that elevation and slope were the main factors affecting the severity distribution and infection rate of charcoal disease. Outbreak of charcoal disease had profound adverse effects on the structure of oak forests، and this was influenced by environmental variables. Finally، preparing the epidemic models of disease requires an understanding of how environmental variables influence the interaction between host and pathogen. The findings of this study may provide an appropriate model for the management and control of the charcoal disease and provide protection and restore the forest ecosystem.