Studies Of Integrated Control Technology And Application Of Important Pests And Diseases In Rice

Rice blast,sheath blight,false smut,planthopper,striped rice borer,leaf roller,etc..are the important diseases and pets of rice,causing serious influence on rice yield and quality.With the aim of effectively controlling the rice diseases and pests,in vitro inoculation test,we firstly using 15 representative M.oryzae single-spore isolates isolated from LTH in taojiang,Hunan,were performed to infer the resistance blast genotypes and then to screen the resistant varieties in some rice cultivars of Hunan province.The toxicity of seven fungicides against the Magnaporthe oryzae,Rhizoctonia solani and Ustilaginoidea virens were determined in the laboratory.Meanwhile,Simultaneously,in order to provide reference for the research and application of integrated pest management technology and the cultivation and distribution of rice varieties in Hunan,field trials for integrated use of biological and chemical pesticides were carried out,according to the actual local rice production status in Taojiang of Hunan.1.Fifteen M.oryzae single-spore isolates with the known avirulent genes isolated from LTH in taojiang,Hunan,were used for pathogenicity test in 55 rice cultivars by in vitro inoculation at 5 leaf stage.Based on the results,the virulence frequency（VF）of the 55 rice cultivars ranged from 46.67%to 93.33%.Among these,Zhenyou 5627（VF=46.67）showed a relatively strong resistance（20%≤VF<50%）.Thus,it could be widely used in the Hunan region.Cluster analysis was carried out by the longest distance method.The result revealed that,under the 0.68 similarity coefficient level,the 55 tested rice cultivars were divided into31 types,with the Pi-20 gene showing the highest frequency,followed by Pi-k^s and Pi-ta.Lu Liangyou 996,Tai Liangyou Hua Zhan and Quan you 851,which contain this kind of blast resistance genes,can be widely used in Hunan area.2.The toxicity of seven fungicides containing 3 kinds of different action mechanisms against M.oryzae,R.solani and U.virens were determined in the laboratory.According to the determination result,Fluindapyr（codenamed IR9792）had the strongest toxicity with EC₅₀0 1.01 mg/L,against M.oryzae in the 3 succinate dehydrogenase inhibitor（SDHI）fungicides;pyraclostrobin had the highest toxicity with EC₅₀0 0.01 mg/L in 3 kinds of Strobilurin fungicides against M.oryzae;the EC₅₀0 of prothioconazole,a triazole thione fungicide,against M.oryzae was 0.70 mg/L;As to R.solani,thifluzamide,a（SDHI）fungicide,had the highest toxicity with EC₅₀0 0.07 mg/L;the toxicity of coumoxystrobin against R.solani was 0.52 mg/L;the EC₅₀0 of the prothioconazole against R.solani was 1.19mg/L.The EC₅₀0 of Pyraziflumid（codenamed NNF-0721）,a（SDHI）fungicide,against U.virens was 1.98 mg/L;azoxystrobin in Strobilurin had the highest toxicity against U.virens with EC₅₀0 0.17 mg/L;the toxicity of prothioconazole against U.virens was 1.43 mg/L.The results suggest that the above 7 kind of fungicides were further developed as ones of controlling important diseases in rice.3.Field trials of integrated use of biological and chemical pesticides were conducted in Taojiang,Yiyang City,Hunan Province.The result clarified the control efficacy of major rice diseases and pests,such as rice blast,rice false smut,rice sheath blight,rice thrips,rice planthopper,striped stem borer and rice leaf roller.The results showed that the four schemes both had good control effects on the main rice diseases and pests.Therefore,these results may provid a reference foundation for the rational application of pesticides and reduction of chemical pesticides.