Snow fungi causing damage on black pine regenerations in the Dedegol mountain (Isparta)

The study was conducted in order to investigate the incidence of and the severity of diseases caused by the snow fungi; Herpotrichia juniperi, Phacidium infestans and Gremmeniella abietina in natural regenerations of Pinus nigra subsp. nigra var. caramanica in the high mountain forests of the Dedegöl Mountain (Isparta). It was hypothesized that the snow related fungi co-occur and the occurrence, incidence and severity of disease caused by each fungus are correlated with the site and host characteristics. Field measurements were carried out on 100-m-long and 4-m-wide transects orientated more or less parallel to the contour lines. Seedlings and saplings within these plots were investigated for symptoms and signs of the snow fungi. The duration of snow cover on sample plots was evaluated through satellite-derived snow cover maps of NASA?s Moderate Resolution Imaging Spectroradiometer (MODIS) analysed in GIS data. The mean incidence of snow related fungi in the sample plots was 48,7%, ranging between 24- 69,4 % within the sample plots. Disease incidence and severity varied considerably between the investigated P. nigra regeneration plots. Disease incidence of H. juniperi ranged from 0 to 23,3% (overall mean: 9,2%) while disease severity ranged from 0 to 9,8 % (overall mean: 3,3 %). G. abietina was found in all P. nigra regeneration plots. Its overall mean incidence (26.6%) was slightly lower on P. nigra than that of P. infestans which was observed on 251 pines (31.9%). Similar results were obtained for the disease severity which was 12.4% for G. abietina and 17.1% for P. infestans. The impacts of some site conditions on the occurrence of the disease agents were significant. Host density and aspect fitness index were important factor for both H. juniperi and P. infestans. Moreover, shadow effect of trees and nearest neighbour index was also controlling factors on the occurrence of P. infestans. Occurrence of G. abietina was significantly correlated with the number of snow covered days during winter period. The disease incidence and the severity of each of these pathogens were also controlled by the same factors affecting their occurrence. On the other hand, elevation was also found to be an important factor on the disease severity and incidence of P. infestans. The co-occurrence of H. juniperi and P. infestans, and P. infestans and G. abietina in the research area were statically significant. While site aspect fitness index was controlling factor for both of the pair-wise co-occurring of the pathogens H. juniperi -P. infestans and P. infestans and G. abietina, the former was also related with the number of total snow covered days. However the co-occurrence of H. juniperi and G. abietina was not significant, the nearest neighbour index was slightly expository for their alignment. H. juniperi was more likely to be found on shorter individuals compared to the other two pathogens. Vitality of pines was correlated only with the occurrence of G. abietina. In other ways, G. abietina was found to be more prevalent to occur on less healthy individuals.