2012年5月22日星期二

About pencycuron : Efficacy of fungicidal seed treatments against pre-emergence damping-off and post-emergence seedling root rot of growth chamber grown canola caused by Rhizoctonia solani AG-2-1 and AG-4


Authors Kataria, H. R.; Verma, P. R.
Twenty-one fungicides were tested in vitro against the mycelial growth of an AG-2-1 and an AG-4 isolate of R. solani. Sixteen of these fungicides were evaluated as seed treatments against pre-emergence damping-off and 8 against post-emergence seedling root rot of canola [rape] cv. Westar (Brassica napus) and cv. Tobin (B. campestris). Seed was planted in soilless mix infested with an isolate of AG-2-1 or AG-4, or their mixture. Benodanil, benomyl, carbathiin (carboxin), cyproconazole, flutolanil, furmecyclox, iprodione, thiabendazole and tolclofos-methyl showed strong in vitro activity against both isolates. Fenpropimorph, flusilazole, propiconazole, triadimenol and vinclozolin had moderate activity and tebuconazole, triadimefon and chlorothalonil poor activity; while fenarimol, imazalil and nuarimol were ineffective against both isolates. Pencycuron gave very strong inhibition of the AG-2-1 isolate but was ineffective against the AG-4 isolate. Fenpropimorph, furmecyclox, iprodione and tolclofos-methyl, applied to Westar and Tobin seed at 1 g a.i./kg, provided about 90% control of pre-emergence damping-off in pots infested with either isolate AG-2-1, AG-4 or both. Furmecyclox and iprodione at 2-4 g a.i./kg were the most effective fungicides against post-emergence seedling root rot caused by the AG-2-1 isolate. Cyproconazole provided 90% control against damping-off (AG-2-1) at the lowest rates of 0.03 and 0.12 g a.i./kg seed of Westar and Tobin, respectively, but gave poor control of seedling root rot. Generally a higher quantity of fungicide was required in cv. Tobin than in cv. Westar for an equivalent level of disease control. This was related to the larger number of seeds per g in Tobin (418) than in Westar (277).



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