The presence of black, powdery spore masses of the fungus between the outer fleshy scale and the adjacent papery scale or between the layers of papery scales. The spore masses are usually heaviest around the neck of the onion and have a tendency to follow the veins down the sides. On onions with thin or light papery scales these spore masses are usually visible through the scales. Onions that have black mold between the scales are very susceptible to Black Mold Rot.

Onions- Black Mold