Stemphylium leaf blight of onion

A foliar blight disease of onion (Allium cepa L.) and garlic (Allium sativum L.) hitherto unreported from India has been described from Varanasi, U. P. The infection is confined to the leaves and inflorescence stalks. The conidial stage of the pathogen is more injurious to the plants, whereas the perithecial stage occurs on the inflorescence stalks in isolated locations. The conidiophores and conidia typical of the genus Stemphylium Wallroth are formed during the early development of the disease followed by perithecia predominantly developing on the peduncles. The perithecia were also induced to develop in artificial culture and were identical in diagnostic characters to those from the field. The conidia and ascospores from both host and artificial culture were reciprocally pathogenic to onion and garlic. Morphology of the fruiting structures indicated identity of the pathogen in its conidial stage with Stemphylium vesicarium (Wallroth) Simmons and in the perithecial stage with Pleospora allii (Rabenh.) Ces. and de Not., to which they are referred respectively.