Development, colonization and field control efficacy of Bacillus amyloiquefaciens X-278 tablets

Through the screening of different carriers, nutrients (carbon and nitrogen) and adhesives, the tablets of Bacillus amyloiquefaciens X-278 (X-278 in short) was developed, which could be applied in cotton root and was convenient for storage and transportation. The storage stability of the tablets was detected. By rifampicin labeling method, the colonization ability of X-278 in cotton root, stem, and in rhizosphere soil were determined. The field control efficacy of X-278 tablets, X-278 fermentation liquor, and Bacillus subtilis wettable powder to cotton verticillium wilt were studied by randomized block design method. The results showed that using diatomite as carrier, mass fraction of 15% glucose as carbon source, mass fraction of 30% peanut cake as nitrogen source, mass fraction of 20% starch as adhesive, tablets of X-278 with smooth appearance and uniform color could be developed by dry pressing method. The moisture content of the tablets was 0.5%, and the living bacteria content was 7.4×107 cfu/g. There was no miscellaneous bacterium detected, and all the indicators were up to the standard. Forty days after applying X-278 tablets in cotton root, the colonization number of X-278 reach the highest, which was 1.56×103 cfu/g in the root, 3.6×103 cfu/g in the stem, and 3.8×106 cfu/g in the rhizosphere soil. The effective duration of the tablets was up to 60 d. The results of field experiment showed that the control efficacy of X-278 tablets against cotton verticillium wilt were superior to that of the fermented liquid and B. subtilis wettable powder. When applied at dosage 0.6 g per plant, the control efficacy of X-278 tablets against cotton verticillium wilt reached 86.34 %.