Abstract: Naked eye and microscopic observations show that when T. laricinum is parasitized by S.filum, the colour of its urediosporus is changed from reddish orange to grey brown. Atlater stage, the urediospores lose their germinating ability, and S. filum conidia Only occur at uredinia base. The metabolic products in fermentation liquid of S. filum containthree resistant substances. From the second ten days of July to that of September, theamount of conidia is more than that of urediospores, indicating that the infected level by T. laricinum is decreased with increasing parasitic rate of S. filum.

Key words: Sphaerellopsis filum, Triphragmiopsis laricinum, Host, Grain for Green Program (GPP), net carbon sequestration, carbon leakage, carbon cost, greenhouse gas.