Study On The Resistance Of Differert Tall Fescue Varieties To Pythium Diseases

Pythium disease is one of the most common and serious diseases of turfgrass, and have a largeimpact on the landscape and economic value of the lawn, causing inconvenience to the use andmanagement of turf. In this study,11pythium strains collected from golf course have been isolatedand identified clearly the types of the pathogens and the damage what it had cause. On the same time,the seeding pot experiment was adopted to comprehensively evaluate and compare disease resistanceof44tall fescue materials which came from different contries and regions, after that the the excellentdisease-resistant germplasm materials could be found out. In addition, on the lad conditions,7kindsof fungicides were chosed to take the toxicity tests so that the effect of different kinds of fungicidesagainst the growth of mycelium and the formation of sporangium of P. aphanidermatum could beascertained. On the otherside, the seed treatment taked on tall fescue was used to confirm the Controleffects of different kinds of fungicides on P. aphanidermatum on potted plants test.The main results:1.11pythium strains collected from the golf course was isolated, cultured, and identified as Pythiumaphanidermatum from morphology. The pythium strain’s optimum growth temperature was35℃,and the pythium strain grew fast in25~35℃. The optimum pH value was7.5, and the strain grewwell in the pH value of6to9. rDNA-ITS sequence of the strain determination and Homologycomparison revealed that the strain was Pythium aphanidermatum. The phylogenetic tree wasconstructed using MEGA5.0software, and knew that the pythium AF452151and the pythium strainhas the nearest genetic distance from the phylogenetic tree. Strain with strong pathogenicity wasselected through pathogenicity test on Jaguar4G.2. Using soil inoculation method, the experiment was conducted by measuring the survival rate, plantheight, biomass, plasmalemmapermeability, proline content at the seeding stage of44tall fescuevarieties. Pythium diseases resisentance in44tall fescue varieties was comprehensively analyzedby principal component analysis. The rusults showed that the risistance of Jaguar3G, Quest,Innovationist, Arid3and Lindbergh was high. And WG3B, Plato, Crossfire Ⅱ,Sofia NO.5,Aristotle were moderate resistance to Pythium diseases. While there were many varietiessusceptiblly to Pythium diseases, especially92-116, Easycare, Jaguar4G and Super watch dogwere much higher susceptible to Pythium diseases3. Laboratory toxicity tests results indicated that the effects of these fungicides were significantlydifferent in inhibiting the growth of mycelium and the formation of sporangium of P.aphanidermatum. Cymoxanil mancozeb, Mancozeb and Propamocarb had the betterinhibiting effect on the hypha growth and the EC50values of these fungicides were1.28mg/L,1.28mg/L,3.26mg/L. While in the inhibiting experiment of the formation ofsporangium of P. aphanidermatum, Pyraclostrobin, cymoxanil mancozeb and Mancozeb performed well with the EC50value0.09mg/L,0.21mg/L,0.46mg/L. Seed treatment againstPythium diseases of tall fescue was also conducted, and cymoxanil mancozeb and Mancozebhad the better control effect. Base on the toxicity tests and seed treatment, cymoxanilmancozeb75%WP and Mancozeb80%WP could be recommende for control Pythiumdiseases of turgrass.