Yield loss of lentil caused by Uromyces viciae-fabae

Abstract

Yield loss in lentil (Lens culinaris Medik.) due to rust (Uromyces viciae-fabae [Pers.] J. Schröt) was determined by assessing crop and disease parameters at different growth stages and leaf canopy layers in field epidemics at Akaki, Ethiopia. The epidemics were created by inoculation of the rust-susceptible cultivar EL-142 with U. viciae-fabae and spraying plots with tebuconazole at different frequencies. The epidemics produced disease progress curves that varied significantly in the rate (rL ) of temporal progression and area under the disease progress curve (AUDPC). The rust epidemic, in particular between early flowering and early pod formation, had a significant influence on seed yield, pods per plant and seed mass. Mean seed yield losses up to 41.6% were recorded. The number of seeds per pod remained unaffected by the disease. The effect of rust on seed yield of lentil can be predicted with AUDPC and critical-point models using disease severity assessed on the upper canopy layer in the early flowering stage. Every 1% increase in rust severity reduced seed yield by 8.4%. Rust severity ≥ 4.7% at the critical early flowering stage significantly reduced seed yield, and hence, any measure that keeps severity below this threshold level would be advisable.