• Initial symptoms - water soaked areas on the outer surface of scales
• Later, a green to blue green, powdery mould may develop on the surface of the lesions
• Infected areas of fleshy scales are tan or grey when cut
• In advanced stages, infected bulbs may disintegrate into a watery rot 

Identification of pathogen:

• Penicillium digitatum, P. oxalicum, P. expansum, P. luteum
• Produces enormous number of spores on a broom like conidiophore
• Saprophytes on plant debris and senescent plant tissue
• Invasion - through wounds, bruises, or uncured neck tissue
• Optimum conditions include moderate temperatures (21° to 25°C) and high relative humidity

• Avoid wounds and insect damage to bulbs
• Harvest and handle onion bulbs with a minimum of bruising or wounding
• Cure the bulbs so the necks are dry 
• Store bulbs at temperatures of 41°F (5°C) or less with low relative humidity