Detection and Identification of <i>Botrytis</i> Species Associated with Neck Rot, Scape Blight, and Umbel Blight of Onion

Fig. 3D. Symptoms of umbel, scape, and flower blight (shown here) caused by Botrytis aclada and B. allii. Lesions can occur at the top, middle, or lower end of the scape, often resulting in lodging once the lesion has girdled the scape, which affects seed set. Concentric grey rings may form in the girdling lesions as a result of sporulation of the fungus beneath the outer cuticle. The fungi sporulate on senescing tissues, including the spadix (membranous sheath that covers the immature umbel), anthers, and petals (shown here).



Image from Plant Health Progress article:
Detection and Identification of Botrytis Species Associated with Neck Rot, Scape Blight, and Umbel Blight of Onion