Identification and pathogenicity of Fusarium oxysporum causal agent of wilt seedling Chestnut-leaved oak (Quercus castaneifolia) in Golestan province

Chestnut-leaved oak (Quercus castaneifolia) is the most important species that its regeneration is limited by several problems such us pests and the fungal diseases. In order to isolate and identify the fungi associated with oak seed and pathogenicity of certain fungi on seedling, sampling carried out during 2007 in Loveh forest and Golestan park of Golestan province. Collected seeds then surface sterilized with 0.5% hypochlorite, each section of seed tissue cultured on potato dextrose agar media. After sub-culture and providing of the fungi pure cultures, Fusarium oxysporum isolated and identified by spores characteristics, their size and color with 28, 16, 56, 40 frequency percentages in Loveh forest and 20, 12, 12, 32 frequency percentages in Golestan park. The frequency percent of the fungi in Loveh forest (35) is the higher than Golestan park (19). pathogenicity test, was performed by inoculation of spore suspension (2×10⁶) on collar. The re-isolation of test fungi was attempted after 6 weeks, using PDA. The sections were taken from roots near the stem base. Symptom of disease was including spot wilting on leave and rot root seedling. After the re-isolation, F. oxysporum was identification that is indication this fungi is pathogen on seedling oak.