Effect Of Fungicide Application Technology On Seed Yield In Field Pea Under Variable Mycosphaerella Blight Pressure

Mycosphaerella blight, caused by Peyronellaea pinodes (Berk. & A. Bloxam) Aveskamp, Gruyter & Verkley (syn. Mycosphaerella pinodes (Berk. et Blox.) Vesterg.), is a destructive foliar pathogen of field pea that is managed, in large part, through application of foliar fungicide at flowering. The fungicides are usually applied into dense crop canopies, so reaching the lower areas of the canopy where the pathogen is initially most active is a challenge. Field trials were conducted across the Canadian prairies from 2008 to 2011 to assess the efficacy of various nozzle numbers and orientations, droplet sizes, and water volumes for the management of Mycosphaerella blight to increase yield in field pea. Pea plants were assessed for disease severity during flowering and seed yield was measured. In 10 of the 13 trials, double-nozzle configurations provided a 15% reduction in disease severity and up to a 60% increase in yield. In contrast, droplet size and angle of application had no effect on field pea yield. Water volume trials using up to 400 L ha(-1) improved fungicide efficacy relative to control treatments, however, volumes above 400 L ha(-1) resulted in high-disease severity and lower yield, likely as a result of fungicide run-off due to saturation of the leaf surface. When deciding on effective sprayer techniques for fungicide application, disease pressure, environmental conditions and cultivar characteristics are important to consider.