الملخص

Abstract This study was conducted in the laboratory and nursery of the Department of forest sciences, College of Agriculture and Forestry/ University of Mosul, the aim of this study was to investigate the seasonal distribution of root rot disease, which causes severe damage to cypress seedling Cupressus sempervirens L. , this study showed through a field survey conducted of some private and public nurseries in Mosul city during September and the November of 2020 and January , March, May and July of 2021, as it was found that the highest rate of infection with the disease was in May 2021, it amounted to 22%, and that the lowest rate of infection was in January of the same year,which amounted to 8%, Fusarium solani was appeared at highest rate 50% in July 2021, and the lowest rate of isolation reached 8.33% of Rhizoctonia solani in September 2020 and January 2021. The results of study concentrations effect of Platanus occidentalis L leaves extract on fungal growth rates showed that alcoholic extract had the highest inhibitory effect on the growth of Rhizoctonia solani fungus, which was 100% at the fourth concentration than the first concentration of aqueous extract which showed the lowest inhibition rate 3.75%