Abstract:Root and stem rot of yam is a main soil-borne disease which severely inhibits the development of yam production industry in China. A field plot experiment was carried out to study the effects of bio-organic fertilizer on the suppression on root and stem rot of yam and plant growth. The results indicated that bio-organic fertilizer could control root and stem rot of yam by reducing the length and the percentage of disease spot. The length of the disease spot of yam tuber in the treatments T1 (CK+450 kg/hm2 BOF), T2 (CK+750 kg/hm2 BOF) and T3 (CK+1050 kg/hm2 BOF) were reduced by 65.1%, 77.2% and 78.0%, the percentage of disease spot were reduced by 67.6%, 80.0% and 81.7% respectively compared with CK. Bio-organic fertilizer could promote the growth of yam, compared with CK the fresh weight of yam tuber in the treatments T1, T2 and T3 were increased by 15.2%, 32.0% and 37.1%, the length of yam tuber were increased by 6.0%, 11.3% and 19.5%, the diameter of yam tuber were increased by 10.9%, 23.6% and 50.9%, the yield of yam were also raised by 15.3%, 32.2% and 37.3% respectively. Soil microbial environment was improved, the amounts of soil bacteria and actinomyces in the treatments of T1, T2 and T3 were increased evidently by 1.04, 1.31, 1.41 times and 1.09, 1.18, 1.71 times, while that of soil fungi was decreased by 21.9%, 46.9% and 50.0% respectively compared with CK. Bio-organic fertilizer has wide application prospects on yam because of its disease-control and growth-promotion.