Efficacy of fungicide treatments to control Stemphylium leaf blight of onion in Brazil, 2024

Stemphylium leaf blight of onion, caused by Stemphylium vesicarium, has caused significant losses in recent harvests, especially during the bulb formation period. This trial evaluated the effect of spraying seven fungicides on the area under disease progress curve (AUDPC) and on the commercial yield of onions, under natural field inoculation. All treatments differed from the nontreated control in terms of AUDPC and yield. Foliar sprays using difenoconazole + pydiflumetofen, fluazinam, and fluopyram resulted in the highest yields. This information may assist producers and technicians in adopting better disease management strategies.