Lemon tree pests and diseases

The lemon tree is a fruit tree widely known in many countries for its rich fruits, lemons. It is not uncommon to find lemon trees and gardens and even in large pots, and considering that, like all fruit trees, it is a plant that takes a long time to start bearing abundant fruit, it is worth knowing its weaknesses well.

For this reason, in this article, we have compiled a list of the main pests and diseases of the lemon tree , as well as a few tips on how to treat and prevent them.

Lemon tree pests – names and photos

There are really several pests that can affect this citrus, but these are the main pests of the lemon tree :

Lemon miner

It is a miner insect that burrows inside the leaves, feeding on them. Its damage is concentrated in the young leaves, and it can be recognized by the fact that the attacked leaves begin to show yellowish or brown spots and the leaves begin to roll up and fold in on themselves until they finally fall.


Aphids are green insects of very small size, less than 5 mm. These tend to settle on the buds and flower buds of the plant, feeding on them. In this way, the tree is reduced in its ability to develop new leaves and its fruits appear with deformations that make them unsuitable for consumption or commercialization.

Cottony mealybug

The mealybug in the lemon tree is usually seen during the summer, when temperatures are high and humidity is very low. These insects, which are covered in whitish waxy secretions, settle on the stems and underside of leaves, hiding in groups. It is important to locate them as soon as possible so that they can be easily treated before they become too widespread.

Red spider

This mite is only slightly larger than aphids, although it is easier to locate due to its striking red color and the cobwebs it creates between leaves that allow it to move through them. It is not one of the most harmful pests, but it feeds on the plant and impairs its development. It usually appears in summer, like the cochineal, since it needs dry environments and high temperatures.

Lemon tree diseases – names and photos

Next, we mention the main diseases of the lemon tree .

Alternaria alternata

This disease is caused by the fungus named Alternaria. It appears when the waterings are excessive and the tree has too much humidity. This is one of the diseases of the lemon tree with wrinkled and yellow leaves , so when this fungus attacks its leaves they look like this and get worse as the tree weakens, until they turn brown, wilt and fall.


This is produced by a viroid and causes vertical cracks and scales to appear on the bark of the lemon tree , as well as dwarfism in the young shoots and yellow spots. Once it affects, unfortunately, all the rest of the attacked tree can only be eliminated so that it does not spread to others.

Sadness virus

This is a very serious disease, which in the most extreme cases can kill the lemon tree in a few weeks. Aphids are its main propagators and their range of symptoms is very wide, from the cessation of their growth and weakening until the tree enters flowering at a time that does not correspond to it. As with exocortis, only the affected tree can be removed to prevent it from spreading to others.


It is a type of mold caused by the Penicillium italicum fungus that is commonly found on the rind of fallen fruit. The spots are white with different shades of green in the center.


This disease is viral and causes the bark to shed or even show gummosis in some areas of the trunk and branches. The tree can be saved if it is treated in time, although its cure is not definitive. 

How to prevent and treat pests and diseases of the lemon tree

To prevent pests and diseases of citrus fruits such as lemon trees , the basic care for the cultivation and maintenance of the lemon tree must be taken into account , make sure that its condition is optimal on a day-to-day basis, surround it with other plants with which protect yourself, such as lavender or calendula.

Be aware of possible symptoms of tree health problems. For example, if your lemon tree shows yellow leaves with green nerves, it means that it needs a greater supply of iron, so you should look for a fertilizer rich in it. If it is not fixed with it, then the problem is that you are watering it excessively.

Finally, follow these tips to treat the most common pests and diseases of the lemon tree:

  • Against the leaf miner, the red spider and the aphids, the simplest thing is to spray Neem oil on the affected areas, which will eventually eliminate the pest.
  • In the case of the cottony mealybug, you can prepare your own insecticide by mixing one part water with one part burning alcohol in a regular 1.5-liter bottle and add a teaspoon of dish soap. Spray the mixture on the affected areas of the lemon tree and it will not take long to finish it.
  • The case of the Penicillium fungus is easy to treat with fungicides that contain copper.
  • Psoriasis can be alleviated by scraping the diseased areas when spring is over and covering the affected area with Zineb.
Lemon tree pests and diseases

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