The field survey had done to isolate and diagnose the fungus Alternaria alternata on Rosa damascena  that Collected from three nurseries in Maysan province, as well as pathogenicity for therse isolates done. The results showed that the highest rate of injury in the nursery Alzhor was 97.2 %. Then after the nursery Alsalam percentage of injury was 96.3 % and Significant differences compared to the nursery Altor rate of injury was 70.9%. It has been isolated and diagnosed four  isolates of the fungus A. alternata from the plant leaves Rosa damascena  that showed symptoms of disease leaves spotted and diagnosed  isolates by comparing the phenotypic characteristics of the fungus pathogen on PDA medium, the results showed the presence of different degrees of pathogenicity according to the isolation, Isolation  A2 were more pathogenesis  ability was 79.5%  followed by isolates (A1, A3, A4) were (72.2, 68.2 and 63.7%) respectively. Significant differences were observed for all isolates  compared to the control treatment. This is the first record of the fungus Alternaria alternata  on this plant in Iraq.

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