(South Dakota)

Spring wheat filed studies in South Dakota have shown the incidence and severity of foliar diseases is sometimes suppressed by Cl fertilization.    Fixen et al (1986b) reported a "dramatic and visually obvious" effect of Cl fertilization on leaf rust (incited by Puccinia recondita) and a leafspot complex (incited by Septoria avenae f. sp. triticea and Pyrenophora tritiic-repentis)at a field site in 1984 (Figure 2).   The suppression effects of Cl were secondary to those achieved with propiconazol (Tilt) and hence were not be considered a substitute for this foliar fungicide (P. Fixen. personnel communication).

Growth chamber experiments on spring wheat have tended to support observations in the field that enhanced Cl nutrition in the plant can suppress leaf rust.  These have included studies with spring wheat cultivars inoculated with Puccinia recondita (Rizvi et al.,1988).

Relative water content in leaves

    Foliar disease suppression by Cl fertilization and foliar fungicides (Tilt) resulted in delayed leaf senescence and greater relative leaf water content in spring wheat (Figure 3).  These results were obtained at the identical location discussed under Figure 2.