Studies On Control Effect Of Combination Bio-control Agents With Chemicals And Fertilizers Against Cotton Fusarium Wilt

It is known that cotton Fusarium wilt is difficult to control, and recently scientists have explored more effective methods to control the disease. As a soil inhabitant, the pathogen has a high capacity to resist the severe environment and is hard to manage. In these methods, the combination of them tend to be applied for controlling the occurrence and development of diseases. The actinomycetes with bio-control effects are important microorgnism resources. The application of bio-control has already played a essential role in bio-control. The preparation of bio-control microorganisms has traditional advantages compared with the fungicide in the environmental compatibility and safety, although the disadvantages such as the complexity and uncertainty of natural environment can not be ignored which result in the difficulties of being popularized. Therefore, the combination of bio-control agents, chemicals and fertilizer seems a pressing measure to control the plant diseases for a better service for agriculture.Based on the study of bio-control agents, which were isolated, screened and kept in our laboratory, the bio-control agents SC11, 153 and FO47 were carried out into solid fermentation. The bio-control agents powders were combined with carbendazim, compound fertilizer and urea to control the cotton Fusarium wilt in order to explore the effects of fungicide and fertilizer on the functions of bio-control agents in preventing diseases and promoting growth, which provided theoretical references for the study of combination of bio-control and chemical manage.Dual cultures was used to test the antagonistic effects of SC11, 153, FO47 on the target pathogen in the plate. The results showed that the isolate SC11 has the most significant inhibitory effect whose inhibition rate reached 67.5%. The inhibition rate of 153 were 55%, respectively. The fermentation brothes of the three bio-control agents all had inhibitory effects on the target pathogen, of which the isolate SC11 had the most significant one. All the three bio-control agents had persistent inhibitory effects on the target pathogen to different degree. To test the resistances of the three bio-control agents to several chemicals, the growth rate method was used to screen the appropriate concentration of chemicals. The results indicated that isolate SC11 had significant resistance to the three tested chemicals and wide scope of chemical concentrations. Two measures were carried out: the effects of cabendazim on the growth of bio-control agents in the plate; the effects of cabendazim on the growth of bio-control agents in fermentation broth. The inhibitory effects of different cabendazim concentration on bio-control agents growth were tested and the results showed that SC11 had a more significant resistance to cabendazim compared with 153 and FO47.The results of fertilizer effects on the bio-control agents growth showed that compound fertilizer and urea had little effects on the bio-control agents growth and the feasibility of combination of biocontrol agents and fertilizer to control cotton Fusarium wilt deserves further study. The pot experiment was carried out to test the effects of combination of bio-control agents, chemicals and fertilizer in preventing cotton Fusarium wilt and promoting the cotton growth. The combination treatment had significant efficiency in controlling cotton Fusarium wilt compared to the single-factor treatments and was more significant compared to the control. As to the comparison of the three bio-control agents, strain SC11 had the most significant effect in controlling cotton Fusarium wilt when combined with chemicals and fertilizer. The combination of strain153, chemicals and fertilizers had capacity in promoting the cotton growth. Some treatments even increased by over 100% in the production of cotton. The pot experiment also demonstrated that the combination of chemicals and fertilizer with bio-control agents showed the potential in controlling plant diseases and promoting their growth.This study took two measures of bio-control and chemical control in managing the cotton Fusarium wilt with the combination of chemicals and fertilizers with bio-control agents, and the results showed this combination indeed improved the bio-control agents effects in controlling diseases and promoting growth, which revealed the advantage of combining the chemicals and fertilizers with bio-control agents and supplied a new solution to the effective control of plant diseases.