The effects of chitinooligosaccharide on the germination vigor and capacity of tobacco seeds, the inhibitive activity of chitinooligosaccharide to two important tobacco pathogens---Phytophthora nicotianae Breda de Hean var. nicotianae Waterh and Alternaria alternata (Fr.) Keissler, the control effectiveness of chitinooligosaccharide to tobacco black shank and brown spot based on the preparation and refine of Trichodema chitinase and chitinooligosaccharide were systematically studied in this paper respective...