Screening Of Biocontrol Bacillus Spp.and Its Suppression On Botrytis Cinerea

Botrytis cinerea is a pathogen causing various plant fungal diseases,which has a great impact on yield and quality.The storage loss of grape caused by gray mold is about 20%-30% every year.At present,chemical agents are the main means to control Botrytis cinerea.The irrational use of chemical agents causes a large amount of environmental pollution,and pesticide residues also affect people's health.With the deepening research on biological control of plant diseases,a large number of biocontrol bacteria and their metabolites have been screened and excavated.Biological control bacteria are increasingly recognized and accepted by people for their strong stress resistance,innocuity and other advantages.It has been reported that Trichoderma and boscalid can be used to control gray mold of tomato,tobacco and other crops.However,there are relatively few researches on controlling Botrytis cinerea by biocontrol Bacillus,as a biocontrol bacterium for controlling various plant diseases,is a kind of bacteria with important research significance and provides basis for sustainable development of agriculture.Therefore,in our research,grape rhizosphere soil was collected from vineyards in xinjiang,shandong and changli of hebei,and Bacillus strain was isolated.At the same time,we carried out confrontation culture between Bacillus strains and Botrytis cinerea pathogens in order to obtain Bacillus strains with biocontrol effect,and confirmed their classification status through morphological observation and molecular identification.Finally,we used biocontrol Bacillus strain+Water soluble fertilizer in a field experiment.In order to obtain the host plant harmless and efficient biocontrol bacterial strains.The main results of our research are as follows:(1)Twenty-five strains of Bacillus were isolated.Through the confrontation culture between the tested strains and Botrytis cinerea in vitro,we found that HT3 and LLong had obvious inhibitory effects on Botrytis cinerea,which indicated that HT3 and LLong could be used as potential antagonistic strains against Botrytis cinerea.(2)Based on the molecular identification results,we identified HT3 strain as Bacillus subtilis and LLong as Bacillus cereus.Through field control experiments,we found that the combination of Bacillus subtilis HT3+trace element Water soluble fertilizer had a better control effect on Botrytis cinerea,with the control effect reaching 85.68%,followed by the combination of Bacillus cereus LLong+trace element Water soluble fertilizer,with the control effect reaching 82.07%.(3)In contrast,the control effect of chemical agent procymidone on Botrytis cinerea was lower than the former two.We provided scientific basis for the research and development of biological control agent and the control of Botrytis cinerea.