First report of Botrytis aclada as a new causal agent of Botrytis Brown Stain on Onion (Allium cepa)

Abstract

Botrytis Brown Stain on onion normally appears as a superficial, dark-brown discoloration of the dry scales of onion bulbs, which are not marketable if strongly infested. Four further Botrytis species associated with diseases of onion (B. aclada, B. byssoidea, B. porri, and B. tulipae) were tested for producing the disorder on six onion varieties. Only B. aclada was capable of causing brown stain, whereby all varieties developed symptoms of the disorder. The fungus was reisolated from the coloured tissue of all symptomatic bulbs. This is the first report of B. aclada as a causal agent of Botrytis Brown Stain on onion.