ipm

MIT College Of Management (MITCOM)

Post Harvest Losses in CITRUS

MIT College Of Management (MITCOM)

ANTHRACNOSE

CAUSE Infection by the fungus,Colletotrichium gloeosporioides.SYMPTOMS•Superficial leathery appearance•Silver/grey to dark lesions.•Tear-staining pattern common.•Pink tinge (spores) under humidconditions.OCCURRENCE•Infection occurs by rain-splashduring autumn.•ethylene degreening increasessensitivity to anthracnose.CONTROL•Dead wood should be pruned asthe fungus harbours in deadbranches.• Field sprays of copper-basedfungicides should be applied priorto autumn rains.•Postharvest treatment withBenzimidazole fungicides mayreduce fruit losses.

MIT College Of Management (MITCOM)

SEPTORIA SPOT

CAUSE The fungus, Septoria depressa.SYMPTOMS• Dark brown collapsed lesions, with a purpletinge.•Black specks develop in decayed area.OCCURRENCE•Mainly inland citrus regions.•Infection occurs in autumn but remains dormantuntil cool conditions.•Fruit more susceptible after frosts.CONTROL•Field application of copper-based fungicides.

MIT College Of Management (MITCOM)

BLUE & GREEN MOULD

CAUSE Fungal infections of Penicilliumdigitatum (green mould) and P. italicum (bluemould).SYMPTOMS•Softening of damaged tissue.•White fungal growth, which progressively turnsblue or green as spores develop.•Postharvest fungicides (Imazalil) can arrestspore development resulting in white only fungalgrowth.OCCURRENCE• Infections develop from damaged areas.•The growth of mould increases with storagetemperatures (up to an optimum of 27oC).

MIT College Of Management (MITCOM)

•Late season fruit more susceptible.•Damaged rind is more susceptible.CONTROL•Careful handling reduces damage to rind.•Good hygiene and sorting reduces spore loadand infection rates.•Sanitation destroys spores in recirculating waterand packingline equipment.•Postharvest fungicides should be applied within24h of harvest.•Lower storage temperatures slow down fungaldevelopment.

MIT College Of Management (MITCOM)

MECHANICAL INJURY

CAUSE. Damage by direct impact withsharp or blunt object.SYMPTOMS•Well defined cuts or rubbed areas.•Reddish/brown depressed and dried outareas.•Sometimes surrounded by a lightercoloured ‘halo’ of oleocellosis.OCCURRENCE•caused by long stems, fingernails,damaged bins and protruding objects inpackinglines.

MIT College Of Management (MITCOM)

•Small injuries and impacts become moreobvious during storage due to dehydrationor development of oleocellosis.CONTROL•Careful harvesting and transport.•Sort out small injuries and blemishes.•Maintain grading equipment.

MIT College Of Management (MITCOM)

CHILLING INJURY (CI)

CAUSE Rind discolour or collapse due to lowstorage temperatures.SYMPTOMSThere are several forms of CI:• Superficial light grey/brown blemish (cold scald).•Dark blown collapsed areas,with irregularboundaries (storage spot).•Brown ‘halo’ effect can surround collapsed tissue.OCCURRENCE• The incidence of CI on oranges is greatlyincreased when storage temperatures are below10oC for periods of 6 weeks or more.

MIT College Of Management (MITCOM)

•Early season fruit is more susceptible to CI.•Damaged rind is more susceptible to CI.CONTROL•Stepped storage temperature regimes. eg., 2-3weeks @100C, followed by 3 weeks @ 50C.•If fruit is held below 30C then they should be atmarkets within 6 weeks from harvest.•Postharvest fungicide application may reduce theincidence of CI. eg., TBZ.