Evaluation of selected fungicides for the control of Rhizoctonia brown patch disease of turfgrasses in vitro
1999
Ooi, B. B. | Kamaruzaman S. | Rosli M.
Rhizoctonia brown patch disease caused by Rhizoctonia solani Kuhn is the most widespread turfgrass disease worldwide and is especially important in warm and humid countries including Malaysia. An in vitro study was conducted to compare the efficacy of Azoxystrobin, Pencycuron, Pencycuron + Tebuconazole and Tebuconazole against Rhizoctonia solani using the poisoned food technique. Six concentrations comprising of0, 250, 500,750, 1000 and 1250 ppm active ingredient (a.i.) of each fungicide were used and the colony diameters were measured perpendicularly daily for seven days to obtain the mean colony diameter. Results showed that Tebuconazole has the highest inhibitory effect on the fungal growth at all levels of concentration tested. At concentration of 250 ppm a.i., inhibition of 100% (colony diameter of 0.6 cm), 97.8% (colony diameter of 1.2 cm) 89.8% (colony diameter of 1.9 cm) and 46.8% (colony diameter of 5.0 cm) was obtained for Tebuconazole, Pencycuron, Pencycuron + Tebuconazole and Azoxystrobin respectively. The ED50 values of 0.1 ppm, 0.2 ppm and 748.8 ppm were obtained for Pencycuron, Pencycuron + Tebuconazole and Azoxystrobin respectively. Maximum inhibition of Rhizoctonia solani was achieved at 250 ppm a.i. for Tebuconazole and between 500 to 1000 ppm a.i. for the other fungicides. Therefore, the order of effectiveness based on the ED50 values was Tebuconazole > Pencycuron > Pencycuron + Tebuconazole > Azoxystrobin.
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