Pests and diseases of the lemon tree

What are the lemon tree diseases ? The lemon tree is one of the most beloved fruit trees in orchards: it is a citrus that produces a large number of fruits, which have an acidic flavor that is pleasant enough to give an exquisite flavor to different dishes. In addition, it does not require special attention, although it may have some other problem.

But, what are the pests and diseases of the lemon tree ? And, more importantly, how do they heal?We recommend that you have a lemon tree 4 seasons. 


  • 1 Pests of the lemon tree
    • 1.1 Miner
    • 1.2 Aphids
    • 1.3 Cottony mealybug
    • 1.4 Red spider
  • 2 Lemon Diseases
    • 2.1 Alternaria alternata
    • 2.2 Virus of sadness
    • 2.3 Exocortis
    • 2.4 Penicillium
    • 2.5 Psoriasis
  • 3 Other problems

lemon tree pests


Minador, one of the diseases of the lemon tree

The lemon tree can be attacked by a leafminer insect, which mainly affects the young leaves. This insect forms galleries as it feeds. As a consequence, brown spots will appear and the leaves will end up curling until they finish wilting and falling.


Aphids, one of the pests of the lemon tree

Aphids appear when there is high environmental humidity and temperatures remain above 15ºC. They are very small insects, less than 0.5cm long, that perch on flower buds, buds and leaves, which turn yellow . Thus, the tree cannot develop new leaves, and the fruits end up developing deformations which means that they cannot be consumed.

It can be prevented by spraying the plant from time to time, but if it already has aphids, it will be necessary to treat it with Neem Oil.

cottony mealybug

Cochineal on lemon tree

The cottony mealybug loves summer; that is, high temperatures and a dry environment. In these months there are many plants that take advantage of the good weather to grow as much as they can before the cold arrives. But any error in its cultivation will cause these parasites to affect the lemon tree, finding them on the underside of the leaves and on the stems.

It can be combated by making this ecological insecticide:

  • Mix equal parts water and pharmacy alcohol in a liter and a half bottle.
  • Then, add a small tablespoon (of coffee) of dishwashing liquid.
  • Cap the bottle, and stir well to mix.
  • Finally, fill a spray bottle, and treat your lemon tree.

Red spider

Red spider

The red spider is a 0.5cm red mite that favors the hot and dry environment of summer . It produces spider webs thanks to which it can go from one leaf to another. Although it is not an extremely dangerous pest, it greatly weakens plants because it feeds on their cells.

To avoid it and/or to control it, it is recommended to use a yellow chromatic trap that you will place near the tree . If the plague is widespread, it is best to treat with acaricides, or with diatomaceous earth if we prefer to use natural products.

lemon tree diseases

alternaria alternata

alternaria alternata

It is caused by the fungus Alternaria. It is characterized by weakening the tree to the point of causing the death of both the leaves and the stems. It advances quickly, so it is important to prevent it by avoiding excess water

virus of sadness

It is the most serious disease that citrus fruits can have, since it is capable of killing them in a matter of a few weeks or months . It is spread mainly by aphids, and causes a wide variety of symptoms, such as flowering out of season, weakening of the tree, little or no growth.

There’s no cure. Unfortunately when a tree has this virus, what should be done is cut it down and burn it.



It is a disease caused by the citrus exocortis viroid (CEVd) that causes the appearance of scales and vertical cracks in the bark, as well as yellow spots on the greenest shoots and stunting.

The only treatment that exists is to cut down the affected tree and burn it so that it cannot transmit the disease to other specimens. As a preventative measure, virus-free lemon trees and grafts that are not susceptible to exocortis should be purchased and disinfected pruning tools should be used.


penicillium in orange

It is the typical greenish or white mold that is seen on fallen fruits. It is caused by the fungus Penicillium italicum , which causes circular patches of mold to appear on the shell . Fortunately, it does well with copper-containing fungicides. Dilute 30 grams in 10 liters of water, and spray the plant to combat the disease.



It is a disease transmitted by a virus that causes the appearance of scales on branches, trunk twigs . In Spain it is not fatal, but in other countries it can end the life of the tree in a few months.

You can tell that your lemon tree has been affected if you see irregular areas, if the bark seems to come off and/or if it has gummosis (rubber exudation).

There is no definitive cure ; however, you can scrape diseased areas in late spring and topcoat with 65% Zineb.

Other problems

The lemon tree is a relatively hardy citrus fruit that is very easy to care for and produces a large number of fruits. However, sometimes you can have other problems that have nothing to do with pests or diseases, but with some carelessness that we have had.

So that you know what to do, here we tell you what are those other problems that you may have and how to solve them :

  • Yellow leaves : if you see green nerves, it is due to a lack of iron, which can be given quickly with fertilizers rich in this mineral; Otherwise, the tree is receiving more water than it needs and, therefore, the irrigation frequency must be reduced.
  • Leaves that lose color : lack of light. Place in a brighter area so that they recover their natural color.
  • Leaf fall : it can be for various reasons, such as a sudden change in temperature (for example, the one that occurs when you take it from the nursery to your garden), being exposed to drafts, lack of water, or natural death (the leaves have a limited life expectancy, so they fall off as new ones appear). In principle, there is no reason to worry too much. You just have to keep the lemon tree well watered, and put a mulch of leaves or pine bark if you recently had it, and that’s it. If you have it inside the house, keep it away from drafts so that its situation does not worsen.
  • The plant does not grow : if it is in a pot, it is because its roots have run out of space and it is necessary to transplant it to another at least 4 centimeters wider during the spring, when the temperatures, both maximum and minimum, are above 15ºC; if it is in the garden, it is most likely that it lacks fertilizer. As its fruits have culinary uses, you should use organic products, such as the manure of herbivorous animals or guano, to fertilize your tree.

Hopefully you can enjoy your lemon tree.

Pests and diseases of the lemon tree

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