Identification And Chemical Control Of Brown Patch' Pathogeny Of Turfgrasses

1. The biological characteristics of R. SoIani Test of the pH suits the growth of Rhizoctonia Solani : It can grow in pH from 5.0 to 9.0, but grow better in acid and neutral environment; when the p1-I is 6.5, it grows best. The relation of tempreture and the growth of R. Solani : The test is held in thermostat at different temperature. The result shows that R. Solani can grows from20C tO 35 OC, but grows best at 300C.2. The pathogenic ability of R. Solanithe incubation period: The test is held in illuminating incubator at differenttemPeratWe. At 20. 25. 30. 35 C, the incubation period in Keamcky bluegrassare 3.0 5.7,2.7 -- 5.3,2.0 5.0 and 2.0 -- 5.3 days seperately; ln creepingbentgrass are 3.3⁶.3,2.7--6.3 .2.0--5.7 and 2.0⁶.0 days seperately; In tallfescue are 3.0--6.3,2.0⁵.7,2.0⁴.7 and 2.0⁵.0 days seperately; In perennialgraSs are 4.7⁶'7,3.7⁶.3,3.0--6.0 and 2.7⁶.3 days sePerately. pathogenic ability: Rhizoctonia Solani are pathogenic to all of Impact,, Highland, Crossfirell and Cutter. Both the disease percentage and disease index keep going up from 20⁽I? to 300C. From 30? to 35?, the disease percentage of Impact and Cutter keep rising , highland and crossfirell keep 100.00%;The disease index of impact,, highland and cutter keep rising, while that of crossfirell descends. 3.The choose of fungicides and the study of their use methods 4 fungicides are chosen from 10 ones with growth rate method which have good controlling effect to Rhizoctonia So/ani . Max them two by two according to their physical and chemical characters , and find three good composes which are Myclobutanil ?Thiophanate-Methyl( 1:1), Myclobutanil + Fenbuconazole (2:1), Thiophanate-Methyl+Thifluzamide(4: 1). test of fungicide spraying: The chosen fungicides are used on the turfgrasses at different doses and different interval. The best schemes are: 1. Myclobutanil -I- Thiophanate-Methyl, 9.17 mgIL,7d interval;2. Myclobutanil + Thiophanate-Methyl, 18.33 mg/L,14d interval;3. Myclobutanil+Fenbuconazole, 14.58 mgIL, 7d interval.