Diseases Diseases

What Are The Causes Of Citrus Tree Diseases


Citrus is the common name for the plants in the Rutaceae family. Examples are lemon, lime, orange etc. Citrus is thought to have originated in the South of Asia, and is now cultivated worldwide for its fruit and essential oil. The fruit is rich in many nutrients we need to keep healthy, the chief being Vitamin C, which is present in large quantities in citrus fruit. This also means that citrus tree diseases have to be studied and prevented, to ensure that there is a consistent supply of these agricultural products. This article will tell you about the most common citrus tree diseases and what causes them.


The most common citrus tree diseases are citrus brown spot, citrus brown rot, verrucosis/scabs, melanose, citrus canker, black root, black spot, many kinds of mold etc. There are also citrus tree diseases which result in the falling off of leaves.

Citrus tree diseases can be caused by bacteria, fungi, parasites or other reasons. Here is a description of some citrus tree diseases and what causes them:
Citrus greening is one the citrus tree diseases that originated in Asia, and is caused by an insect called the Asian citrus psyllid. This disease causes the leaves of the tree to turn yellow, and the fruit starts to become irregularly shaped. Green patches appear on the fruit, and it tastes bitter and bad even when it is fully ripe.

Citrus trees like warm weather, but this weather can lead to many citrus tree diseases, especially those pertaining to the leaves. Fluctuating temperatures or temperatures above 65F often lead to problems in the leaves of citrus trees – they may yellow, become mottled or fall off. All of this affects the plants ability to function properly, a it cannot photosynthesise in the absence of leaves.


Citrus cankers are another one the worrying citrus tree diseases that cultivators have to deal with. What is worse, cankers are highly contagious, spreading fast from tree to tree through factors such as the rain, people's clothes and hands, on the air etc. This is one of the citrus tree diseases that affects all sorts of citrus trees, such as orange, lime, lemon, tangerine, grapefruit etc. This disease is caused by bacteria, and it leads to lesions on the fruit and leaves and premature dropping off of the same.

Tips and comments

Melanose is one of the fungal citrus tree diseases. It happens most often in grapefruit, but is not always limited to it. The fruit will retain its flavour and quality, but it will become unattractive to the sight. Yet another one of the citrus tree diseases caused by fungus is greasy spot – it causes the leaves to become discoloured, and oily rings appear on them as the disease progresses. Ultimately, the leaves fall off.

Other causes of citrus tree diseases are aphids – in small numbers, they do not harm the trees much, but larger populations can affect trees significantly. An aphid infestation leads to the gradual falling of leaves, and affects the bark and twigs of the tree too.

By Smita, published at 04/02/2012
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