Diagnosis And Control On Diseases Of Rice Stem Rot,rice Downy Mildew And Rice Root Nematode

Occurrence and control of the three diseases (rice stem rot sclerotia disease, ricedowny mildew, rice root nematode disease) were researched during2009～2011in Fujianprovince. The results were as follows:1. The pathogen species of rice stem rot sclerotia disease were identification inFujian province, the disease resistance of rice varieties was preliminarilyunderstanded, the trichoderma strains were screened for disease control. Two kinds ofsclerotinia pathogen were isolated and identified from rice sclerotia stalk rot plant.Identification of morphological characters showed that they (Helminthosporiumsigmoideum Cav.) and spherical sclerotinia stem rot (Sclerotium hydrophilum Sacc.).The result of pathogenic determination was that two kinds of sclerotinia pathogen caninfect rice, the most pathogenic of the small globular sclerotinia, the small globularsclerotinia is the dominant pathogen population in high-quality rice disease regions.pathogenicity results of two main sclerotial pathogens to cultivated high-quality ricevarieties (Liangyouhang Ⅱ, Liangyou3773, Yiyou673and Tianyou huazhan) showedthat: differences resistance among different rice varieties,Tianyouhuazhan and Yiyou673were resistant varieties. The results of room flat confrontation experimentalshowed that: trichoderma viride, trichoderma longibrachiatum and false trichodermawere better biocontrol effects on the two sclerotinia pathogens. The biocontrol effectof Trichoderma viride was99.95%, and the result provided the basis for the biologicalcontrol of rice stem rot sclerotia disease.2. The pathogen of rice downy mildew was identified in Fujian, the biologicalcharacteristics of rice downy mildew were researched. The rice downy mildew wascollected from Fu'an city, the pathogen was identified as the phytophthora largespore(Sclerophthora macrospora (Sacc.) Thirumctal). biological characteristic resultsshowed that the PSA and oatmeal agar were the best medium for rice downy mildewpathogen mycelia growth; mannitol and sucrose were the best medium for myceliagrowth in different carbon source; sodium nitrate was the most conducive to mycelialgrowth in different nitrogen sources; the optimum C/N ratio were20:1and30:1in the different C/N ratio;12~36℃was fit for the mycelia growth, but the optimumtemperature were24-28℃; thepH5-11were fit for the mycelia growth, but themost optimum pH of the mycelia growth was5.0.3. The relationship of rice root nematode infection and premature senility wasresearched, and comprehensive management of rice root nematode was established.The comprehensive management was "Tobacco-rice crop rotation, protection root toprevent senility ".The results of pot experiment and field chemical control were that:nematode infection had a significant effect on rice premature senility. topdressedearing fertilizer can prevent and slow rice premature senility, and then increased cropyield. The result of the nematicide(cadusafos, fosthiazate) against root nematode wasthat, the best prevention period was reviving stage.The results of field experiment andinvestigation showed that: the selection of tobacco-rice rotation and vegetables-ricerotation can significantly reduce the number of rice root nematodes in the rice field.Rice root nematode decreased by98.34%in tobacco after rice, rice root nematodedecreased by90.58%in vegetables after rice. The cost-effective and feasible methodof prevention and treatment of latent rice root nematode were implemented of therotation of tobacco-rice or vegetable-rice rotation.