Lemon Tree Diseases

Lemon Tree Diseases

What are the diseases of the lemon tree ? The lemon tree is one of the most beloved fruit trees in the orchards: it is a citrus fruit that produces a large quantity of fruits, which have an acid flavor 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 important if possible, how do they heal?

Lemon pests


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 result, brown spots will appear and the leaves will wind up until they finish wilting and falling.

It can be fought with Neem Oil.


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

The cottony cochineal loves summer; that is, high temperatures and 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 their cultivation will cause these parasites to affect the lemon tree, finding them on the underside of the leaves and on the stems.

You can fight doing this ecological insecticide:

  • Mix equal parts water and pharmacy alcohol in a liter and a half bottle.
  • Next, add a small spoonful (of the coffee) of dishwasher.
  • Cover the bottle, and stir well to mix.
  • Finally, fill a sprayer, and treat your lemon tree.

Red spider

The red spider is a mite about 0,5cm red color that favors the warm and dry summer . Produces cobwebs thanks to which you can go from one sheet to another. While it is not an extremely dangerous pest, it weakens plants a lot because it feeds on their cells.

To avoid it and / or to control it, it is recommended to use a yellow color trap that you will place near the tree . In case the plague is very widespread, it is best to treat with acaricides, or with Neem Oil if we prefer to use natural products.

Diseases of the lemon tree

Alternaria alternata

It is caused by the fungus Alternaria. It is characterized by weakening the tree to the point of killing both the leaves and the stems. It advances quickly, so it is important to prevent avoiding excessive irrigation .


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

The only treatment that exists is to cut the affected tree and burn it so that it can not transmit the disease to other specimens. As a preventive measure, you must acquire virus-free lemons and grafts that are not susceptible to exocortis and use disinfected pruning tools.


It is the typical greenish or white mold seen in the fallen fruits. It is caused by the fungus Penicillium italicum , which causes the appearance of circular spots of mold on the skin . Fortunately, it is treated well with copper compound fungicides.



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

You can sense that your lemon tree has been affected if you notice 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 the diseased areas in late spring and coat it with 65% Zineb.

Other problems

The lemon tree is a relatively resistant citrus, very easy to care that produces a large amount of fruit. 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 you know what to do, then we tell you what are these other problems you may have and how to solve them:

  • Yellow leaves : if you see green nerves, it is due to 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 frequency of irrigation must be reduced.
  • Leaves that lose color : lack of light. Place in a more luminous area so that they recover their natural color.
  • Fall of leaves : they can be for several reasons, like abrupt change of temperatures (for example, the one that takes place when you take it from the nursery to your garden), for being exposed to the air currents, for lack of water, or for natural death (the leaves have a limited life expectancy, so that they fall as they grow new). In principle, there is no reason to worry too much. You just have to keep the lemon well watered, and put a pad of leaves or pine bark if you have it recently, and ready. If you have it inside the house, stay away from the air currents so that your situation does not get worse.
  • The plant does not grow : if it is in a pot, it is because its roots have run out of space and it has to be transplanted to another one at least 4 centimeters wider during the spring, when temperatures, both maximum and minimum, are higher than 15ºC; If it is in the garden, it is most likely that it lacks fertilizer. As its fruits have culinary uses, you must use organic products, such as the manure of herbivorous animals or guano, to fertilize your tree.

Don Burke

I am Don Burke, one of the authors at My Garden Guide.  I am a horticulturist that cultivates, grows, and cares for plants, ranging from shrubs and fruits to flowers. I do it in my own garden and in my nursery. I show you how to take care of your garden and how to perform garden landscaping in an easy way, step by step.I am originally from Sydney and I wrote in local magazines. Later on, I have decided, more than two decades ago, to create my own blog. My area of specialization is related to orchid care, succulent care, and the study of the substrate and the soil. Therefore, you will see many articles dedicated to these disciplines. I also provide advice about how to improve the landscape design of your garden.

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