Stemphylium Leaf Blight of Onion

Abstract

Stemphylium leaf blight of onion is an important disease that occurs in most onion growing regions of the world. The disease damages the onion leaves causing defoliation that can reduce bulb yields and lower the quality and export potential of the produce. During the 2017-18 growing season, significant outbreaks of Stemphylium leaf blight occurred in commercial fields of onion in New Zealand, including the Pukekohe (Figure 1), Waikato, Hawke’s Bay and Canterbury regions.