Identification of pathogen:
- 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
- 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
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| Water saoaked areas | Blue or green powdery mould | Grey spores at cut region |
