Isolation, identification and pathogenicity of fungal agents associated with root and crown olive trees in Khuzestan province

During a survey in the years 1384-1386 from olive orchards in Khuzestan province, a sample of olive trees showing symptoms viz wilting, dieback and in some cases decline was collected. After washing and surface sterilization, the suspected samples were cultured on PDA medium and incubated at 25 ° C. In total, 124 fungal isolates from root and crown of olive were identified including a species from Verticillium (V. dahliae with 35 isolates), three species of Fusarium (F. solani with 23 isolates),) F. equiseti with 20 isolates), (F. semitectum with 4 isolates), three species of Cylindrocarpon (C. destructans with 20 isolates), (C. didymum with 8 isolates), (C. obtosisporum  with 9 isolates), and R. solani with 5 isolates that were multinucleate and belonged to anastomosis group AG-4. The pathogenicity test of V. dahliae, F. solani, F. equiseti and C. destructans isolates were performed on olive seedlings 12 months by dipping the roots of seedlings in spore suspensions while R. solani isolates pathogenicity test was performed on a 12 -month-old olive trees and wheat. Results of pathogenicity tests showed that the isolates obtained from three species including F. solani, V. dahliae and C. destructans were as strongpathogens, F. equiseti as moderate pathogenic and  R. solani as weak pathogen on olive. This is the first report of species F. equiseti and C. destructans on olive in Iran and species F. semitectum, C. didymum and C. obtosisporum as the olive pathogens.