Study On The Controll Effect Of Several Fumigants To Ralstonia Solanacearum And Other Soil-Borne Pathgen

The ginger bacterial wilt has been a serious and destructive disease, which greatly affected ginger's quality and yield. There is no significant methods to control it, the most effective method is soil fumigation. Methyl bromide is one of the most widely used fumigants, it has been used in a lot of ginger-growing areas in China. However, methyl bromide is a significant ozone-depleting substance, has been listed as controlled substances in the Montreal Protocol. After 2015, It will be banned worldwide. Therefore, the research for alternative soil fumigants is a focus at home and abroad.In this thesis, Ralstonia solanacearum, soil nematode, Fusarium spp. and Phytophthora spp. are the main objects we study on. Adopted the indoor fumigation test method, Biological activity tests and field efficacy trials, we studied respectively the biological activity and the effect in field of methyl iodide,1,3-dichloropropene and chloropicrin some types of single and compound alternative fumigants, to select alternative technologies to methyl bromide for controlling the ginger bacterial wilt effectively in national conditions. The results now are summarized as follows:The treatment of methyl iodide 30g/m2 and 40g/m2,1,3-dichloropropene 25g/m2, chloropicrin+1,3-dichloropropene (1:1) and chloropicrin+1,3-dichloropropene (1:2)on Ralstonia solanacearum have good prevention and control results at all depth of soil after treatment, the reducing rates are above 89.76%,87.64%,73.85%,69.32%和69.50%.At harvest,the the reducing rates of methyl iodide+chloropicrin (1:3) and methyl iodide+ chloropicrin (1:5) are above 85.56% and 83.33%.All fumigants have have prevention and control results significantly after treatment, the reducing rates are 100.00% at all depth of soil after treatment. The treatment of chloropicrin+1,3-dichloropropene (1:1) 50g/m2, chloropicrin+1,3-dichloropropene (1:2) 50g/m2 and methyl iodide+chloropicrin (1:5) have good effects on the prevention and control of soil root-knot nematodes, the reducing rates are above 80.58%,78.57% and 85.71%.Against Fusarium spp., the treatment of methyl iodide 40g/m2, chloropicrin+ 1,3-dichloropropene (1:1) 50g/m2 has good result, the reducing rates are above 66.20% and 77.12%.1,3-ichloropropene has weaker result on Fusarium spp., But, compounding with chloropicrin can enhance the effect of killing Fusarium spp., and chloropicrin+ 1,3-dichloropropene (1:1) 50g/m2 is the effective ratio and amount in field.Phytophthora spp. is difficult to control effectively, the treatment of methyl iodide 40g/m2, the compounds of iodomethane+chloropicrin, the reducing rates are above 98% after treatment. At harvesting, the treatment of methyl iodide 40g/m2, methyl iodide+ chloropicrin (1:5) have better prevention and control Phytophthora spp. The treatment of chloropicrin+1,3-dichloropropene (1:1) 50g/m2 is optimal effect, the reducing rates are above 72.30%.After soil fumigation, the treatment of methyl iodide 30g/m2 and 40g/m2, methyl bromide+chloropicrin (1:3), chloropicrin+1,3-dichloropropene (1:1) 50g/m2, their crops are vigorous and growing strong in growth stage, their yields increase significantly in harvest stage. Yield increasing rates are 48.84%,49.30%,51.05% and 202.62%According to the indoor test of fumigants'biological activity and the application effect and yield in field, the fumigants we selected have favorable controll effect on Ralstonia solanacearum, soil nematode, Fusarium spp., Phytophthora spp., they will become proper alternatives of methyl bromide.