Disease-Control And Mechanism For The Spore Bacteria Against Pepper Phytophthora Blight

Pepper Phytophthora blight caused by Phytophthora capsici is an important fungal disease on the crop worldwide. Currently chemical control is the major measure for controlling the disease. However the use of pesticides is restricted because this may induce problems as chemical residues on the crop, fungicide resistance and environment pollution. In addition, the disease arises and spreads at capsicum root, the good effectiveness of using pesticides could not be achieved after appearance of the symptom. In order to adopt the developments of green agriculture, biocontrol may be an alternative to avoid these problems in capsicum disease control. In the present study, antagonistic spore bacteria against Phytophthora capsici were screened from rhizosphere soils of capsicum, tomato and tobacco, and the biocontrol efficiency and mechanisms of the antagonistic bacteria against the pathogen was investigated.1 A total number of 459 bacterial isolates were obtained from rhizosphere soils of capsicum, tomato, and tobacco. From these, 17 spore bacteria showed good antagonistic effects against Phytophthora capsici by dyeing spore and pairing culture on CAA. In greenhouse disease control experiments, the spore isolate Bn-130 was found most effective in Pepper Phytophthora blight control. Spraying with the bacterium cultures, the disease control effects against Pepper Phytophthora blight was 64.7% after 1 d.2 Spore bacteria Bn-130 obviously suppress mycelium growth of P. capsici by antagonism test on CAA plates. The divaricator of mycelium is manifold, vesiclar occurred and it's protoplast aggregated through micropahotography. The result from culture filtrate showed that Bn-130 isolate was efficient for inhibiting mycelium growth and reducing spore germination of P. capsici. Spore germination rate was significantly reduced and malformation of the spore germings. The growth of mycelium was slow, so that the spread of colony was slow.