Shot hole disease, survival and pathogenicity of the causal agent on stone fruit trees of North East Iran

Shot hole caused by Wilsonomyces carpophilus is one of the main constraints to prune fruit production in Iran particularly in Khorasan Razavi province. Causing foliage shot hole in spring and early summer; fruit-spotting and cankers on limbs and twigs during autumn rains. The fungus was isolated from the lesions of twigs and was purified on PDA. The pathogenicity and virulence on detached twigs of six different stone fruit tree species was examined in vitro. The virulence of isolates as measured by lesion length was significantly different among the isolates obtained from different host species. In contrast to other hosts, sour cherry did not show any canker on shoots or twigs and disease progress was just as tissue colonization by the fungus hyphae. Mean comparison was carried out with LSD test (α = 0.05) and did not have any significant difference. The most sensitivity of shoots to infection was related to peach (MS = 12.467) and located at A group among stone fruit species. The results of bud and shoot evaluations indicated that the fungus overwinters as hyphae and conidia in buds, and in the form of hyphae as well as thick-walled globular chlamydospore in twigs. Additionally, viability of recovered conidia ranged from 33 to 90% throughout the dormant season. A better understanding of disease life cycle leading to improved monitoring of the fungal disease will reduce fungicide applications.