A preliminary preparation of endophytic bacteria CE3 wettable powder for biological control of postharvest diseases

Abstract

Recently, there has been an increasing interest among researchers in using combinations of biological control agents to exploit potential synergistic effects among them. In the present study, there were investigated commercially acceptable formulations of Bacillus cereus CE3 wetting powder with long storage life and retained efficacy to control chestnut and other fruit rot caused by Endothia parasitica (Murr) and Fusarium solani. The study sought to develop a new B. cereus formulation that would be more effective and better suited to the conditions of field application. By a series of experiments, the formulation was confirmed as follows: 60% B. cereus freeze-dried powder, 28.9% diatomite as carrier, 4% sodium lignin sulfonate as disperser, 6% alkyl naphthalene sulfonate as wetting agent, 1% K2HPO4 as stabilizer, 0.1% β-cyclodextrin as ultraviolet protectant. The controlling experiments showed that the diluted 100 times of 60% B. cereus wetting powder had 79.47% corrosion rate to chestnut pathogens; and this result is comparable to the diluted 1,000 times of 70% thiophanatemethyl. Safety evaluation results showed that rats acute oral lethal dose 50% was 5,000.35, therefore application of B. cereus wettable powder could not cause a person or animal poisoning. This work illustrated that 60% B. cereus wetting powder had commercial potential; however, to apply this formulation as a biological pesticide in the field, masses production processes need to be further studied.