Preparation Of Ozonized Soybean Oil And Its Control Efficacy Against Apple Valsa Canker

Apple Valsa canker is one of the most destructive diseases of apple (Malus sp.) in themajor apple production area in China. The traditional control method was to scrape thecanker lesion and then brush chemical fungicides. Little reports were avaible for thedisease control in organic apple orchards. Ozone exsits in the natural world. It is unstable,and could easily split into oxygen at ordinary temperature. In mordern agricultureproduction, ozone had been used to control Fuarium oxysporum f. sp. cucumerinum,Pseudoperonospora cubensis (Berk. et Curt.) Rostov. Uncinula necator and Botrytiscinerea Pers. While a few reports about the application of ozone on fruit tree diseasecontrol are avaible. Experimental evidence for the control of ozone against apple Valsacanker is not enough, and if ozone could be used in organic apple orchard to controldiseases need for further research. Vegetable oil were used as carrier to make ozonized oil,and the ozonized oil were tested for the inhibiton to the mycelial growth and the conidialgermination of Valsa mali. Field experiments were applied to test the control effect ofozonized oil against apple Valsa canker. The results of the present thesis could providetheoretical basis and useful product for apple Valsa canker control in organic orchards. Theresults of this study listed as follows:1. The changing pattern of oxidation value according to the ozonization durationperiod extension was illustrated. During the ozonization period from1h to114h, and withthe ozonization time increase, the oxidation value in soybean oil increased correspondinglyat room temperature (25℃),. While after114h ozonization, the oxdation value did notchange significantly. The maximum oxidation value was82.29g/kg in testing conditions.2. The inhibition effect of ozonized soybean oil against ten species of plant pathogenicfungi were evaluted. At the oxidation value82.29g/kg, the inhibition effects of ozonizedsoybean oil against conidial germination of Valsa mali, B.berengriana f. sp. piricola, andAlternaria mali etc. were100%. The inhibition effects of ozonized soybean oil against themycelia growth of the tested10fungi species ranged from87.62%to100%.3. The protective and curative effect of ozonized soybean oil against apple Valsacanker and the effect to apple tree bark callus forming were confirmed. In the experiment of detached apple twigs,24.68g/kg ozonized soybean oil showed significant protectivecontrol effect against apple Valsa canker, the control efficacy was95%. In the field trials infive experimental sites in Shaanxi province,24.68g/kg ozonized soybean oil demonstratestrong curative control effect against apple Valsa canker. The curative control efficacy wasover60%, and the control efficacy for pruning wounds protection was over85%. Thetested ozonized soybean oil showed slightly stimulative effect to apple tree bark callusformation, and it was similar with that of control fungicide3.315%thiophanate-methyl· naphthylacetic acid.