Blue mold rot—Penicillium sp.
Blue mold rot generally appears during harvesting and storage. Initial symptoms include water-soaked
areas on the outer surface of scales. Later, a green to blue green, powdery mold may develop on the surface
of the lesions. Infected areas of fleshy scales are tan or gray when cut. In advanced stages, infected
bulbs may disintegrate into a watery rot.
Avoid wounds and insect damage to bulbs. Handle onion bulbs with a minimum of bruising or wounding; dry
the bulbs with prompt curing of neck tissue. Store bulbs at temperatures of 41° F or less with low relative