Studies On The Preliminary Efficacy And Bio-control Mechanism Of Bacillus Marinus Wettable Powder

In this paper,the preliminary indoor efficacy,pot efficacy,field efficacy,salt tolerance,and the effect of mixture with nutrition additives,as well as the exploration of Bacillus marinus B-9987 bio-control mechanism were investigated respectively.The results could lay the foundation for developing B.marinus wettable powder(WP)as the first marine microbial pesticide in the world.B-9987 has a broad inhibition spectrum.13 fungi tested were inhibited by B-9987.The inhibition efficacy of Sclerotium sp.,Altenaria soleni,Sclerotium sp.and Fusarium oxysporum by B-9987 strain was better than those by HY96-2 strain(the strain of a first commercialized biopesticede within Paenibacillus strains,Paenibacillus polymyxa WP).The results of bio-assay showed that the inhibition efficacy of B-9987 strain,its filtrate and the control chemical pesticide to Phytophthora capsici was equivalent.The pot pathogenic model of tomato bacterial wilt was initial established.The results showed that B.marinus WP can prevent tomato bacterial wilt very well with this pot model.Compared with the control agent P.polymyxa WP,the efficacy of B.marinus WP was not less than that of P.polymyxa WP.Pot test also showed that,B.marinus WP could accelerate the germination of seeds of tomatoes,watermelons,chillies and eggplants.And it has strong effect on the growth of tomato seedlings after transplanted.B.marinus WP has a broad disease control spectrum in field.It can control many kinds of soil-born diseases and leaf diseases,such as tomato bacterial wilt,Chinese cabbage soft rot,melon fusarium wilt,pepper blight,watermelon fusarium wilt,angular leaf spot of cucumber,melon anthracnose,watermelon anthracnose,grey mould of sesame,chinese cabbage downy mildew.In addition,compared with the control agent P.polymyxa WP,it is feasible to determine the dosage and method relative to that of P.polymyxa WP of prophylactic trial of B.marinus WP according to the therapeutic test results of it.Salt tolerance test showed that the salt tolerance of B-9987 was better than that of HY96-2.The addition of nutrition can significantly improve the number of B-9987 in the soil,and the efficacy of B.marinus WP to tomato bacterial wilt,pepper blight and Hami-melon fusarium wilt.The results of inhibition mechanism of B-9987 showed that the mycelium of P.capsici expanded,multi-branched and tufted after treating with B-9987 broth.It also can change the cell permeability of Botrytis cinerea after treating with the filtrate of B-9987 broth.B-9987 could induce the resistance of cucumber to disease.The enzyme activity of POD and CAT and the CAT expression profile associated with the disease resistance were significantly improved after treating with B-9987 broth.