Application of Propiconazole in Management of Stem Rust in Perennial Ryegrass Grown for Seed

Abstract

Stem rust caused by Puccinia graminis subsp. graminicola was controlled by propiconazole in perennial ryegrass (Lolium perenne) grown for seed. Between 1986 and 1992, the fungicide was applied up to six times per year to plants in different stages of growth. A two-application treatment (126 a.i./ha) was effective for increasing seed yield and controlling stem rust, with the first application when spikes began to emerge from the boot and the second when spikes were fully emerged. Stem rust was first observed as early as 29 April and as late as 16 July. Seed yields were smaller when stem rust epidemics began in early spring. A threefold to 10-fold increase in seed yield was observed among cultivars treated with propiconazole compared with nontreated controls