Abstract: In Liaoning province, rust parasite mainly distributes at Benxi, Fushun and Dandong districts. The investigation on its occurred pattern in forest shows that the dispersing peak of its conidia occurrs at 24 and 12 o'clock. The dispersing period is from the second ten days of June to last ten days of September, and the peak is in the last ten days of August. The amount of dispersed conidia is controlled by meteorological factors and particularly by rainfall. The incubation period of rust parasite is about one month. The infected level by larch brown rust decreases with annually increasing parasitic rate of rust, indicating the control effect of rust parasite on larch brown rust.

Key words: Sphaerellopsis filum, Occurred pattern, Larch brown rust