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Anthracnose: Colletotrichium gloeosporioides
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Septoria spot: Septoria depressa
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Blue & Green Mould: Penicillium digitatum (green mould) and P. italicum (blue mould)
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Sour Rot: Galactomyctes citri-aurantii (formally, Geotrichum candidum)
1. Anthracnose: Colletotrichium gloeosporioides.
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Symptoms
- Superficial leathery appearance
- Silver/grey to dark lesions.
- Tear-staining pattern common.
- Pink tinge (spores) under humid conditions.
Occurrence
- Infection occurs by rain-splash during autumn.
- Ethylene degreening increases sensitivity to anthracnose.
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Management
- Dead wood should be pruned as the fungus harbours in dead branches.
- Field sprays of copper-based fungicides should be applied prior to autumn rains.
- Postharvest treatment with Benzimidazole fungicides may reduce fruit losses.
2. Septoria spot: Septoria depressa.
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Symptoms
- Dark brown collapsed lesions, with a purple tinge.
- Black specks develop in decayed area.
Occurrence
- Mainly inland citrus regions.
- Infection occurs in autumn but remains dormant until cool conditions.
- Fruit more susceptible after frosts.
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Management
- Field application of copper-based fungicides.
3. Blue & Green Mould: Penicillium digitatum (green mould) and P. italicum (blue
mould).
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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.
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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.
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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.
4. Sour Rot: Galactomyctes citri-aurantii (formally, Geotrichum candidum).
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Symptoms
- Very soft, watery decay.
- Distinct margin between decayed and healthy tissue.
- Sour odour detectable.
Occurrence
- Infection occurs in damaged fruit.
- Fungicide used to control blue & green moulds may not control Sour rot. (eg., USA accepted
- fungicides).
- Sour rot spores in soil can accumulate in recirculating water in dips and drenches.
- Spreads by contact after packing creating nests of infected fruit in boxes.
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Management
- Careful handling reduces rind damage.
- Apply Guazatine fungicide within 24hrs of harvest.
- Strong emphasis of sanitisers when Guazatine fungicide not approved for use.
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