Study Of Pythium Diseases Of Turfgrasses

1 .Identiflcation The author gathering the Pythium disease samples from Beijing, Hebei, Henan, Tianjin and Sichuan. The pathogens are saperated and cultured, and identificted as 5 genera and some Pythium-like fungi. The 5 genera are P. ultimum, P. aphani- dermatum, P. graminicola, P. amasculinum, P. deliense. 2.The test of pathogenic ability Acording to the rule of Koch,the pathogentic ability of five pathogenies ae test. From small to large they are P. amasculinum, P. deliense, P. ultimum, P. graminicola, P. aphanidermatum. 3.Prevalent factors Inoculate the most powerful pathogeny to the turfgrasses for test, and study the influence of temperature ,moisture,disease resistance of host,soil fertility,and cutting height to the prevalence of Pythium disease.The result shows that the Pythium disease may prevalent when the top temperature 30 0C , relative moisture 90%,bottom temperature 20 0C which sustains more than 14h. Adding P and K to the soil in the summer, and keep turfgrass relative height may reduce the Pythium disease. 4.The test of fungicide With growth rate method, ten fungicides are test indoors for their toxicity. Six ones are chosen which have good restraining effect to Pythium spp. which are Metaqlaxyl, Yizailin,Maneb, Phosethyl-Al, Myclobutanil and Chlorthalonll. After the fungicide spraying test in plotted turfgrasses outdoors, three fungicides are chosen at last which are Metaqlaxyl, Myclobutanil and Phosethyl-Al.