CHLORIDE FERTILIZER EFFECTS ON WINTER-WHEAT INOCULATED WITH FUSARIUM-CULMORUM

Studies in the Northern Great Plains indicate that C1 fertilizers sometimes increase yield and reduce the severity of root diseases in small grains. Little information exists from this region on the relationship between Cl and common root rot incited by Fusarium culmorum (W.G. Sm.) Sacc., or the effect of Cl on winter wheat (Triticum aestivum L.) yield. The objectives of this study were to address these issues. Field experiments were conducted in south central Montana during 1988 and 1989 on a Fort Collins soil (fineloamy, mixed, mesic Ustollic Haplargids) that contained 57 and 39 kg Cl ha-1 (0-120 cm), respectively. The experiment consisted of two cultivars of winter wheat (Redwin and Cree), three seed treatments (heat sterilized F. culmorum, live F. culmorum plus chemical protectant, and live F. culmorum, and four Cl fertilizer levels (0, 22.5, 45, and 90 kg Cl ha-1) in complete factorial arrangement. Inspection of lower stems and subcrown internodes at the soft dough stage indicated no effect from Cl on disease severity. Chloride fertilizer significantly increased grain yield in 1988 (P < 0.001), but not in 1989. In 1988 grain yields at 22.5, 45, and 90 kg Cl ha-1 were not different and averaged 3306 kg ha-1, or 227 kg ha-1 more than plants not receiving Cl. Whole plant Cl concentrations at heading and indigenous soil Cl were not reliable predictors of yield response to Cl fertilizer. Seasonal factors may be important in defining the likelihood of a response to Cl fertilizer in addition to soil and plant Cl status.