The invention relates to a
pesticide, and especially relates to a complex bactericide composed of
bacillus subtilis and a chemical bactericide. The bactericide is used for controlling
brassica rapa pekinensis
downy mildew. The bactericide comprises the chemical bactericide,
bacillus subtilis XM16 CGMCC No.0372, and auxiliary materials. The bactericide is characterized in that the chemical bactericide in the
active components is any one selected from
metalaxyl,
propamocarb, and
mancozeb. A biocontrol bacterium is
bacillus subtilis XM16, with the strain collection number of CGMCC No.0372. A weight ratio of
metalaxyl to bacillus subtilis XM16 is 1-8:1-10. A weight ratio of
propamocarb to bacillus subtilis XM16 is 1-10:15-140. A weight ratio of
mancozeb to bacillus subtilis XM16 is 1-15:1-10. A form of the bactericide is usually hydrophilic
powder or
aqueous solution. The complex agent of the biocontrol bacterium and the chemical bactericide has a substantial synergetic effect in controlling
brassica rapa pekinensis
downy mildew. The biocontrol bacterium bacillus subtilis XM16 is advantaged in high bacteriostatic activity,
high stress resistance, and wide bactericidal spectrum. The biocontrol bacterium is complexed with the oomycetes chemical bactericide, such that the
pesticide dosage is reduced, and controlling effect is improved. The bactericide is an environment-friendly bactericide. The bactericide is advantaged in high
biological safety, low cost, and substantial economic benefit.