Abstract:Streptomyces spectabilis SC11, isolated from soil, has a broad spectrum of antibacterial activity. The control efficacy of SC11 against tomato gray mold was examined by pair culturing on PDA and pot experiments. Pair culturing experiment on PDA showed that SC11 significantly inhibited the growth of Botrytis cinerea in vitro. Pot experiments showed that the control efficacy of SC11 was 65.3%, higher than that of procymidone (55.8%) treatment. The experiments on defense enzymes, MDA and proline in tomato plant showed that the activity of defense enzymes and the content of proline in tomato leaf were induced, but the content of MDA was decreased. Moreover, SC11 obviously promoted the growth of tomato seedlings, plant height, stem diameter and chlorophyll content. These results indicated that SC11 could not only effectively control tomato gray mold, but also improve the defense enzyme activities in plant and promote the growth of tomato seedlings.