Study On The Combined Microbial Agent For The Control Of Cucumber Root-knot Nematode And Fusarium Wilt

Meloidogyne incongnita and Cucumber Wilt,which cause huge economic losses every year are important plant soil-borne pathogens in crops.Increased concerns about the safety of environment and food has resulted in greater interest in biological control instead of chemical nematicides.In this paper,we isolated and screened rhizosphere actinomycetes against root knot nematode and Cucumber Wilt;prevent and control M.incognita and Cucumber Wilt with the combinations.The results were as follows:1.There were 454 actinomycetes including 399 strains isolated from rhizosphere soil and 55 strains sorted in the laboratory.Among them,eighteen actinomycete strains could reduce the hatching of M.incognita eggs and kill M.incognita J2.The actinomycete JZ-22 showed high biocontrol efficacy against M.incognita with in vitro and in vivo experiments.And in the pot experiment,JZ-22 had the highest biocontrol efficacy(51.18%).The strain JZ-22 was identified by morphological and physiological tests combined with 16S rDNA gene molecular analysia,and then the strain JZ-22 was identified as Streptomyces althioticus.Fourteen strains of antagonistic actinomycetes against Cucumber wilt were screened using plate confrontation method.Then pot experiment carried out and screened 3 strains TH-4,TH-5 and ZH-14,which had good biocontrol effect.2.To achieve a higher biocontrol on M.incognita,JZ-22 and endophytic bacterial BCM2,SZ5 and CCM7in combinations were evaluated on cucumber under greenhouse and field conditions.Compatibility was observed in cucumber roots and rhizosphere soil of JZ-22 and endophytic bacterial in combinations.Application of JZ-22+SZ5 was more effective compared to others,which decreased the root galling by up to 60.22%under the greenhouse condition and decrease the root,soil second stage juveniles density and root egg density by up to 92.95%,53.42%and 87.00%,respectively under the field condition.3.Biological agents JZ-22+SZ5 and TH-4,TH-5,ZH-14 was combined to control cucumber wilt and M.incognita.The pot experiment showed that the combination JZ-22+SZ5+ZH-14 decreased the cucumber wilt severity and root galling by up to 65.93%and 60.72%,respectively.And the compound control effect reached 64.67%,significantly higher than the other treatments,and also had good growth promoting effect.