Blue & Green Mould: Penicillium digitatum (green mould) and P. italicum (blue mould).

Symptoms

• Softening of damaged tissue.
• White fungal growth, which progressively turns blue or green as spores develop.
• Postharvest fungicides (Imazalil) can arrest spore development resulting in white only fungal growth.

Occurrence

• Infections develop from damaged areas.
• The growth of mould increases with storage temperatures (up to an optimum of 27 oC).
• Late season fruit more susceptible.
• Damaged rind is more susceptible.

Management

• Careful handling reduces damage to rind.
• Good hygiene and sorting reduces spore load and infection rates.
• Sanitation destroys spores in recirculating water and packingline equipment.
• Postharvest fungicides should be applied within 24h of harvest.
• Lower storage temperatures slow down fungal development.

Image source: http://www.plantprotection.hu/modulok/angol/citrus/mold_cit.htm