NITROGEN AND FOLIAR FUNGICIDE EFFECTS ON WINTER WHEATS

In the eastern region of the Great Plains, yield and seed quality of wheat could potentially be increased by applying additional N and foliar fungicide. Field studies were conducted at two locations in southeastern Kansas from 1987 through 1990 on a Parsons silt loam soil (fine, mixed, thermic, Mollic Albaqualf) to evaluate responsiveness of selected cultivars of hard and soft winter wheat to conventional N (75 lb N/acre, fall-applied) and high N (75 lb N/acre, fall-applied followed by 50 lb N/acre topdressed in late winter) fertilizer applications, with and without foliar fungicide (propiconazole -1[[2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolan-2-yl]methyl]-1H-1,2,4-triazole). Nitrogen level and foliar fungicide responses varied significantly among cultivars, locations, and years. Grain yield, test weight, kernel weight, and heads per square foot were significantly reduced with the higher N level in 3 of 4 yr at one location; however, at the second location, the high N application significantly increased grain yield compared with the conventional N level. Applying additional topdress N significantly increased grain protein at both sites, but foliar fungicide had no effect on grain protein. Yield response to foliar fungicide was dependent upon leaf rust (Puccinia recondita Rob. ex. Desm. f. sp. tritici) severity and cultivar disease resistance. Significant N level x fungicide interactions for grain yield occurred in seven of the eight site-years. Results indicate that decisions to use higher N levels and foliar fungicide should be based upon specific environmental conditions and cultivar selection.