The Identification And Fungicide Selection Of Pathogen Of Greenhouse Watermelon Fusarium Root Rot In Tibet Autonomous Region

Greenhouse vegetable production in Tibet has developed rapidly in recent years,and especially the planting area of cucurbitaceae vegetables is expanding unceasingly,such as watermelon and etc.Nevertheless,root rot disease has become increasingly serious as the planting area expands,which has become one of the significant diseases influencing the local production of watermelon and etc.By taking the root rot of greenhouse watermelon as the research object,this paper conducts a study from symptom description,pathogen isolation and identification,pathogenic biological characteristics and indoor virulence determination,and basically obtains the following results:1.The greenhouse watermelons in Tibet suffering from root rot disease show slower growth rate and weaker growth vigor,and then wither and die in later period,and the diseased plants have brown and rotten roots;2 strains of pathogenic fungus（respectively number as No.1 and No.5）are isolated from the diseased plants with conventional tissue isolation method,and identified as Fusarium solani according to the morphological characteristics and ITS gene sequence analysis.2.Fusarium solani could grow at 15℃-40℃,with the optimum temperature of30℃;Fusarium solani could grow in the selected 13 kinds of carbon-source culture mediums and 13 kinds of nitrogen-source culture mediums,but its growth rate in the culture mediums with lactose as the carbon source as well as the culture mediums with ammonium carbonate and arginine as the nitrogen source is significantly lower than the control group（P<0.05）,namely,has obvious inhibition effect to the pathogenic fungus;while,its growth rate in the culture mediums with arabinose as the carbon source,and the culture mediums with sodium nitrate and histidine as the nitrogen source is significantly higher than the control group,namelyshows obvious enhancement effect to the pathogenic fungus;in addition,the colonial morphology in different carbon and nitrogen source culture mediums is also different.3.Through indoor toxicity determination,the average EC₅₀0 value of the 15 kinds of pesticides is 66.511 mg/L,of which the EC₅₀0 values of 75%NATIVO,40%flusilazole,and 15%difenoconazole?propiconazole（mg/L）are less than 1 mg/L,namely,they are the preferable chemical pesticides for the prevention and treatment of root in theory.