Oranges are round citrus fruits with finely-textured skins that are, of course, orange in color just like their pulpy flesh; the skin can vary in thickness from very thin to very thick. Oranges usually range from approximately two to three inches in diameter.

Diseases in Oranges

  1. [caption id="attachment_4094" align="alignright" width="300"] greasy spot in oranges[/caption]

    Greasy spot.

It’s a fungal disease.

Symptoms

Yellowish-brownish blister spots on leaves, often on the underside of the leaf.

Spots develop into oily looking blisters.

Control

Timely application of copper based fungicide.

  1. Sooty mold.

[caption id="attachment_4096" align="alignright" width="241"] sooty mold in citrus[/caption]

It’s a fungal disease.

Symptoms

Leaves becomes black

This is as a result of honeydew secretions from insects such as white-flies, aphids and mealy bugs.

Control

Use an effective insecticide and also spray copper based fungicide and where there is severe infestation spray again after 14 days.

  1. Citrus canker

It’s a bacterial infection.

Symptoms

Yellow halo-like lesions or scabs on the fruit, leaves and twigs.

Severe infections can cause leaf loss, blemished fruit, fruit drop and die back.

Spread

It spreads easily and quickly on air currents, insects, and birds and on humans by means of clothing and infected implements.

Control

Use copper based fungicide as a preventative measure. Destroy already infected trees to contain the spread of bacteria.

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  1. Root rot

It is caused by the soil-inhabiting fungus from the phytophthora species.

 Symptoms

Dark brownish patches of harden bark on the trunk of the tree.

The infected area is then left as a dark sunken canker.

Control

Remove all leaves and damaged fruit when it falls to the ground.

Prune off all lower branches off the tree so that the tree branches are more than 2 feet from the ground.

Spray the tree with an effective fungicide.

Pests Affecting Oranges

  1. Aphids

[caption id="attachment_4099" align="alignright" width="300"] aphids on oranges[/caption]

They sack the sap out of the leaf.

There is yellowing and the twisting of the leaves, which gives the appearance of deformed leaves. As the severity of the aphid infestation increases, leaf drop and twig and branch die back.

Control

For effective control of aphids use an insecticide e.g. prosper and make sure the underside of the leaf is sprayed thoroughly.

  1. Red mites

They are extremely tiny pest and red or purple in color. These mites infest leaves and fruit. Intense infestations during hot, dry weather can cause leaf drop.

Control

Spray an effective insecticide e.g. karate.

  1. Citrus leaf miner

They feed within the leaves creating distinctive silvery tunnels or 'mines'.           

Damage is usually worst when there is new flushing particularly on young trees below three years old.

Control 

Spray an effective insecticide e.g. karate.