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Citrus Tree Diseases

Ningthoujam Sandhyarani Feb 11, 2019
The common citrus tree diseases are caused by bacteria and fungi, while a few are caused by viruses. Included in the list of diseases are citrus canker, sooty mold, melanose, greasy spot, yellow vein chlorosis, root rot disease and bark scale disease.
Citrus trees, like lemon, orange, and grapefruit are included in the most popularly planted landscaping trees. With their adorable shape, glossy leaves, richly fragrant blooms and edible fruits, these plants are worth growing in your yard.
Nevertheless, planting them is considered challenging by most hobbyists. In addition to the stringent care and extended time required for fruit bearing, the incidences of their diseases and pests are high, especially when they are grown in cold climatic conditions.

The Diseases

Its general care involves providing optimal sunlight, maintaining warm temperature, watering when the top soil dries, occasional fertilization, and pruning once in a while. Nothing can be more disappointing than seeing your fully grown tree affected by a disease.
So, before you come across such a situation, be thorough with the most common citrus tree diseases and pests reported in your area. That way, you can take preventive measures to reduce the chances of disease attacks, and at the same time, increase the fruit yield. Listed next are common diseases afflicting citrus trees.


Of all the diseases of citrus trees, citrus canker is the most serious one that causes devastating damages. It is caused by bacteria and results in the formation of scabs (similar to halo lesions) in the leaves, branches, and fruits.
When detected in the early stages, this contagious disease is treated by applying antibiotic formulation. But, if the disease sets in, the affected tree is killed to reduce further spreading.

Sooty Mold

This is a fungal disease, characterized by black coloration of the affected leaves. The black color is nothing but the spores of sooty mold.
It is triggered by whitely, aphid and alike pest attacks, which leave a sticky, honeydew like substance on the dorsal side of foliage. Hence, treatment for this disease involves controlling insects with correct insecticide sprays, coupled with copper fungicide application.

Greasy Spot

One of the destructive diseases caused by fungus is greasy spot. After infection takes place, the fungal spores germinate within the leaf tissues, causing the lower leaf portion to develop slightly raised blisters.
They appear greasy with time, hence the name citrus greasy spot disease. Other symptoms include leaf yellowing and dropping. Spraying copper fungicide two times in the summer helps in controlling this fungal disease.

Yellow Vein Chlorosis

Yellow vein chlorosis is named with reference to the yellowish coloration of the main vein and lateral veins.
This may be caused due to several factors, of which some are phytophthora foot rot, overwatering, extreme low temperature, physical damage, and other stressful growth conditions. While it is concentrated on the leaves, the barks of diseased twigs may also be affected.


If you notice scabs forming in citrus fruits, particularly in young stages, then it may be the melanose disease. It mostly affects older grapefruit trees.
The fruit quality and the yield remain unaffected, but affected fruits have a lesser market value due to unsightly appearance. Along with fungicide application, pruning is also an easy way to reduce this fungal disease.

Root Rot Disease

As the name goes, it affects the root system. Hence, steps for containing it should be followed as soon as possible, before any severe damage is exhibited by the upper parts. Notable signs include developing brown patches in bark, oozing of plant sap, leaf turning yellow, premature leaf fall and browning of the fruit.
Trim down all the affected twigs and spray appropriate fungicide in correct dose.

Scaly Bark Disease

It is caused by viral infection and it exclusively affects the bark portion. Also known as psorosis, it causes scale formation in the bark of sweet orange and tangerine. Under severe infection, the yield is reduced considerably. Two other commonly reported citrus tree bark diseases are phytophthora gummosis (caused by fungi) and exocortis (caused by virus).
Besides the aforementioned diseases, mild to severe pest infestation is also not unusual for this plant. Some of the pests are aphids, citrus bud mite, orangedog caterpillars, whitefly, thrips, brown soft scale, snail, red mite.
Instead of adopting ways for treating the problems, it is always better to prevent them at the first instant. Once affected, the diseases and pests may spread to remaining trees, leading to significant decrease in the yield.