DIFENOCONAZOLE SEED TREATMENT FOR CONTROL OF DWARF BUNT OF WINTER-WHEAT

We evaluated difenoconazole (Dividend 3FS), thiabendazole (Mertect LSP ), triadimenol (Baytan 30F), and carboxin plus thiram (Vitavax 200) as seed treatments for control of dwarf bunt (caused by Tilletia controv ersa) on the susceptible winter wheat (Triticum aestivum) cultivars Nu gaines and Hatton. Seed was planted at various dates during the fall o f 1990 and 1991 at Logan, UT; Kalispell, MT; Pullman, WA; and Cavendis h, ID. Dwarf bunt was most severe on plants that had developed to the two- to five-leaf stage in late fall before snowfall. Difenoconazole a t 0.12 g a.i./kg provided complete control at all locations when wheat was seeded at intermediate and late dates. A low incidence of dwarf b unt developed when seed treated with difenoconazole was planted at ear ly dates at some locations or when difenoconazole was applied at 0.06 g a.i./kg. The other fungicides tested did not provide adequate contro l.