Abstract: Strain PA-2 was isolated from diseased poplar leaves in Ping'an, Qinghai Province, the metabolites of the strain showed high herbicidal activity to target weeds. According to its culture characters and 16S rDNA sequence analysis, the strain was identified as Aureobasidium pullulans. The objectives were to determine mortality and fresh weight reductions of various weeds and to evaluate the host range of the fungus as influenced by the fermentation filtrate. The fresh weight reductions of A. pullulans to Galium aparine L. var. tenerum (Gren. et Godr.) Reichb., Chenopodium album L., Malva crispa L., Polygonum lapathifolium L., Avena fatua L. for weeds seedlings in the pot tests were 87.25%, 78.46%, 82.25%, 62.11%, 80.27% respectively. Responses of inoculated weeds to A. pullulans ranged from light symptoms to 100% mortality. G. aparine L. var. tenerum (Gren. et Godr.) Reichb. and M. crispa L. exhibited significant reductions in fresh weight. No significant fresh weight reductions were observed for Triticum aestivum L., Vicia faba L., Hordeum vulgare L. plants compared to the control plants. Brassica napus L. and Pisum sativum L. exhibited light spots on A. pullulans inoculated leaves with no significant reductions in fresh weight. These results indicated that A. pullulans could be a potential microbial herbicide for control of target weeds in crops.