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Methods of Applying Tricyclazole for Control of Pyricularia oryzae on Rice. J. D. Froyd, Research Scientist, Lilly Research Laboratories, Division of Eli Lilly and Company, Greenfield, IN 46140; L. R. Guse(2), and Y. Kushiro(3). (2)Area Research Administrator, Lilly Research Laboratories, Division of Eli Lilly and Company, Greenfield, IN 46140; (3)Plant Science Representative, Eli Lilly Japan K. K., 9th Floor Kobe Kanden Building, 15 Kano-Cho 6-Chome, Ikuta-ku, Kobe 650 Japan. Phytopathology 68:818-822. Accepted for publication 4 November 1977. Copyright 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-818.

Tricyclazole [5-methyl-1,2,3-triazolo(3,4-b) benzothiazole] was evaluated for control of Pyricularia oryzae on rice by the following methods of application: soil drench to the seedling flat one day before mechanical transplanting, foliar sprays at different stages of growth, and combinations of soil drench plus foliar spray. Results from 42 field trials were summarized and compared with the performance of several reference fungicides applied according to manufacturers' specifications. Tricyclazole applied as a soil drench at 2.25 g/flat before transplanting effectively controlled leaf blast throughout most of the vegetative stage of growth and reduced rotten neck incidence by 50%. The most effective foliar spray application for rotten neck and panicle blast control was 225-375 g/ha tricyclazole applied less than 10 days before heading (late booting stage). Earlier spray applications necessitated higher rates for equivalent disease control. When tricyclazole was sprayed on plants that had received a soil drench application before transplanting, 150 g/ha at late booting provided acceptable control of rotten neck. Tricyclazole rates for soil drench and foliar applications, as well as numbers and timing of foliar applications, must be determined for different rice-growing areas because of differences in local disease occurrence. Nevertheless, the proper use of tricyclazole should result in equivalent or superior rice blast control with fewer applications than with the fungicides currently being used.