Lesions on onion leaves often appear more elongated than wide and are often described as diamond shaped. Lesions can coalesce making unusual, irregular shaped, larger lesions that girdlea leaf and begin to kill it. The symptoms are more pronounced on flower stalks. Infected leaves and stalks lodge during the latter part of the growing season.

Appearance of necrotic diamond-shaped lesion. These lesions can be small to very large. Larger lesions are not obviously diamond-shaped but tend to be longer, along the length of the leaf, than wider.

As the IYSV disease progresses, concentric rings may, or may not, be present and often lesions become more pronounced, elongated, slightly sunken and lighter green colored.

First appear as straw-coloured, dry, tan, spindle or diamond-shaped lesions, with or without distinct green centers with yellow or tan borders on leaves. The symptoms are more pronounced on flower stalks. Infected leaves and stalks lodge during the latter part of the growing season.

Green islands of tissue can appear within a necrotic IYSV lesion. These types of lesions are less frequent than the tan, completely necrotic, lesions.