Melpat International (Pty) Ltd Citrus Disorders 1. Post Harvest 2. - - PowerPoint PPT Presentation

Melpat International (Pty) Ltd

• 1. Post Harvest
• 2. Crop Management

All controlled by Copper

Citrus Disorders

• 1. Injury caused by chilling process:

 Shipments at -0.5ºC (insect sterilization)  Symptoms similar to frozen produce  Aim to improve rind condition during fruit development  more robust fruit

Reference: Citrus Research International, South Africa

Citrus Disorders – Post Harvest

Most occur post harvest:

Reference: Citrus Research International, South Africa

• 2. Rind Breakdown

 Collapse of the oil glands  Aim:  Nutrient optimisation within tree and carbohydrate allocation, which determine rind condition  Handling

Citrus Disorders – Post Harvest

Reference: Citrus Research International, South Africa

• 3. Peteca Spot:

Citrus Disorders – Post Harvest

Reference: Citrus Research International, South Africa

• 4. Creasing (Albedo Breakdown):

 Physiological Disorder, which results in a separation of cells  Aim:  Ca + Ga Sprays  Ga Timing which does not interfere without having a negative colour effect.  Bearing position and light manipulation

Citrus Disorders – Post Harvest

• Alternaria brown spot
• Citrus black spot

Alternaria alternata Guignardia citricarpa

Reference: Citrus Research International, South Africa

Crop Management – Controlled by Cu

• Sooty mold

Capnodium citri

• Melanose

Phomopsis citri

Reference: Citrus Research International, South Africa

Crop Management – Controlled by Cu

• Scab

Elsinoe fawcetti Pseudomonas syringae

• Black pit

Reference: Citrus Research International, South Africa

Crop Management – Controlled by Cu

• Phytophthora brown rot

Phytophthora nicotianae var. parasitica

Reference: Citrus Research International, South Africa

Crop Management – Controlled by Cu

• Botrytis on lemons

Botrytis cinerea

Reference: Citrus Research International, South Africa

Crop Management – Controlled by Cu

• Bacterial canker

Xanthomonas campestris

Reference: Citrus Research International, South Africa

Crop Management – Controlled by Cu

• Greasy spot
• Septoria spot

Septoria citri Mycosphaerella citri

Reference: Citrus Research International, South Africa

Crop Management – Controlled by Cu

• Pseudocercospora

Pseudocercospora angolensis

Reference: Citrus Research International, South Africa

Crop Management – Controlled by Cu

• Mal secco

Phoma tracheiphila

Reference: Citrus Research International, South Africa

Crop Management – Controlled by Cu

Crop Effect – Copper Blemish Copper Stippling – frequent spraying

Photos courtesy of Dr. Tian Schutte (CRI)

Thrips Mites / Wind

Reference: Citrus Research International, South Africa

Side Effects – not to be confused

Darkening of blemishes

 Spraying time: Late March to Early April.  Always spray at the recommended rate of application and be sure leaves and fruit are well covered.  A second or third spray may be necessary if wet weather persists.  Preferably spray after mid morning when the fruit has warmed up.  Always use the recommended rate of wetting agents. If this is not done, the spray may remain in drops on the fruit and leaves.  Skirt trees and prune the inside of trees to maximise spray penetration, coverage and reduce disease buildup.  If sooty mould is a problem, add 500ml of spraying oil / 100 liters of water.  Some copper formulations may darken wind scars or insect marks.  DO NOT mix copper based sprays with other sprays as this may cause rind burn.

 District variations

Applying copper sprays:

Reference: Citrus Research International, South Africa

Reference: Citrus Research International, South Africa

Front - 1 mL

Reference: Citrus Research International, South Africa

Front - 2 mL

Reference: Citrus Research International, South Africa

Front - 3 mL

Reference: Citrus Research International, South Africa

Front - 6 mL

Reference: Citrus Research International, South Africa

Back – 1 mL Back – 2 mL Back – 3 mL Back – 6 mL

Reference: Citrus Research International, South Africa

Coffee stain effect

Reference: Citrus Research International, South Africa

Effect of spray run-off

Reference: Citrus Research International, South Africa

Botrytis cinerea on grapevine leaves

Reference: Citrus Research International, South Africa

Botrytis cinerea on grapevine leaves

Reference: Citrus Research International, South Africa

Ideal Water Volumes

 Tree Size Dependent  Mature 2500 – 3200 lt/ha (use wetting agent)

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