The influence of nitrogenous fertiliser on the incidence and effects of crown rust (Puccinia coronataCorda) in two ryegrass cultivars

Abstract

Abstract The influence of nitrogenous fertiliser on the incidence and effects of crown rust (Puccinia coronata Corda) in ‘Grasslands Ruanui’ perennial ryegrass (Lolium perenne L.) and ‘Grasslands Ariki’ ryegrass (Lolium (multiflorum X perenne) perenne) was studied in a plot trial. Nitrogen was applied at rates of 20 lb/ac or 140 Ib/ac. The high nitrogen level markedly increased the yield of green herbage in both ryegrass cultivars. In Ruanui perennial ryegrass there was a greater incidence of crown rust at the low nitrogen level, while in Ariki ryegrass there was some evidence of greater disease incidence at the high nitrogen level. However, these differences produced no apparent effects on ryegrass yield. The results are discussed in relation to the mechanisms of disease resistance and techniques for reducing the incidence of crown rust in ryegrass.