Research On Prevention And Treatment Technology Of Rhizoctonia Solani

This study used the orthogonal test which has three factors four levels and nine processing to determine the important factors and conditions that effect the growth and development of rice sheath blight; 18 varieties of rice has been evaluated by the rice sheath blight resistance; The mycelium growth rate method for the determination of 14 kinds of fungicides and three kinds of mixture medicament which is compound with four kinds of fungicides according to the different mixture ratio of indoor antibacterial activity; Wadley method is used to determine the combined effects of the pesticide mixture, and then the synergy effect of fludioxonil and pyraclostrobin was tested by pot trial; Finally, made out 42% fludioxonil and pyraclostrobin EW and a field control effect was carried out.The research results are as follows:1. The influence of Rhizoctonia solani, followed by the growth and development of the biggest factors is medium, the second is temperature, and the last one is illumination time. The optimal growth conditions is oatmeal culture medium, 25 ℃, under the condition of alternating light and dark(12:12).The results of this study laid the foundation to cultivating pathogenic bacteria in the future, it is very important to the whole test.2. 18 rice varieties which cultivated by Jilin agricultural university have significant resistance to sheath blight, the disease index of most varieties is greater than 45%, belong to the susceptible cultivars or highly susceptible cultivars to rice sheath blight. The best resistant cultivars is JINONGDA 82, All of the rice varieties have no highly resistant cultivars.3. Fludioxonil, pyraclostrobin, thifluzamide and epoxiconazole have obviously inhibitory activity with EC50 values of 0.1600、0.1988、0.2250 and 0.6068 mg·L-1 respectively. In the mixture inhibitory experiments, 5∶1 ratio of fludioxonil to pyraclostrobin exhibited good activity to Rhizoctonia solani. The EC50 value was 0.0431 mg·L-1. And efficiency coefficient was 3.84. The Pot experiment indicated that the synergistic mixture effect is obvious when 5∶1 ratio of fludioxonil to pyraclostrobin.4. The recipe of 42% fludioxonil and pyraclostrobin water emulsion(EW),contained 35% fludioxonil, 7% pyraclostrobin, 18% toluene, 4% polyethylene glycoloctyl phenyl ether, 5% Tween-80, 10%DMF, 4% ethylene glycol, 0.5% organic silicone and diluted water up to 100%. Of all the 42% fludioxonil and pyraclostrobin EW indexes for testing, the results show that the product conforms to the quality indicators of water emulsion.5. Not only the vitro experiment bacteriostatic effect of fludioxonil and pyraclostrobin is obvious, but also the field efficacy trials have good performance. When 5∶1 ratio of fludioxonil to pyraclostrobin, under 200 g a.i. ·hm-2 dose, the control effect can reach 92.43%, under 100 g a.i. ·hm-2 doses, the control effect can reach 82.97%, under 50 g a.i. ·hm-2 doses, the control effect can reach 72.80%.So this 42% fludioxonil and pyraclostrobin water emulsion has good control effect on rice sheath blight, it is can be used as effective fungicides for rice sheath blight.