Antagonistic Action of Pseudomonas fluorescens Strain G20-9 to Alternaria alternate Keissler

The antagonistic action of Pseudomonas flourescent to Alternaria alternata Keissler was tested in laboratory.The results showed that the aseptic fermentation fluid of Pseudomonas flourescent G20-9 strain had strong antagonistic effects on the mycelium growth amounts of Alternaria alternata Keissler,and the inhibition rate was 82.1%;the effects of aseptic fermentation fluid diluted to half the concentration was better than that of Dimetachlone.The colonization of G20-9 was determined with dual-resistant label,it was concluded that strain G20-9 could colonize in the rhizosphere and on the leaf surface of tobacco.