Citrus treatments, most common diseases and pests of this flower

citrus citrus

citrus citrus
The Citrus genre is formed of multiple species, such as: the lemon, the grapefruit, the pomelo, the mandarin, plants we call citric plants. These plants are part of the Rutaceae family, which originated from Asia and Europe.

The weather conditions from South-East Europe are not favorable for growing citric plants in gardens, however, for the people living in these areas, the citric plants can be grown indoors, in flowerpots.

Even though taking care of these plants is not exactly easy, the ever-green and pleasant-smelling leaves and the colorful fruits determine the plant enthusiasts to become devoted to growing and looking after the citric plants.

Depending on each species, some citric plants respond better to growing in flowerpots, the small species, for example. When buying these plants, it is recommended to look after the species which love this type of environment and which are auto-fertile (which pollinate themselves). Nowadays, mostly self-pollinating species are being sold. The species which have a naturally rapid growth can be grown in the flowerpots until they reach a certain height.

The small species are the ones which adapt to the indoor environments, species such as limes, kumquats, calamondins, Buddha’s hand, etc.
citrus citrus 1

The citric’s biological cycle contains a vegetation period, which is characterized by the plant’s growth, flowering, rest, which is normally during winter, when the temperatures are low. This rest period is very important because it helps the plant to flower.

Ecological exigencies

Most citric plants have the same demands when it comes to environment conditions and growing these plants as indoor plants must respect those demands.

Light and temperature

These species are light lovers and must be placed in luminous places, during both summer and winter.

During summer, the citric plants prefer to be taken outside to that they could benefit in full from the sunlight. Be careful as placing them under direct sunlight needs to be done gradually, otherwise the plant can suffer from leaf burns. Below you can find information about moving the plants outside during starting with the spring season.

During winter, the citric plants needs cooler temperatures, 10-15 degrees Celsius, in order to enter the relative rest period, which is needed so that the plant can flower in the spring.

High temperatures during winter are not recommended as the plant cannot enter its rest period.

The air’s relative humidity

The citric plants prefer a high air humidity, it is recommended to place these plants near other groups of plants. This aspect must be taken into consideration, especially during winter, when the indoor air tends to be dry.

The plants can be sprayed with water between 2 consecutive watering actions, during the warm season. During winter, the leaves can be sprayed with water only if the indoor temperature exceeds 15 degrees Celsius (below you can find the needed environment conditions for the cold season).

To maintain a high relative humidity, the plant’s flowerpot can be placed on a tray on which rocks were placed. Doing this, the roots are protected from the excess water and the evaporation of the water is good for the plant.

Taking care of citric plants


Frequently, there are problems related to improper plant watering. Excess watering is not recommended, the plant’s soil must not be permanently wet, it must be a bit dry on the surface between 2 watering processes (the first 3-5 cm). Excess watering can lead to root rot, leaf falling and creating an imbalance in the plant’s systems.

Due to excess worrying, sometimes, the plants are heavily watered. It is important to know that citric plants prefer to be watered less and with a larger quantity of water than many times with a small quantity of water.

It is not recommended to water the plants using directly tap water. The water must be kept in lidless vases for a minimum of 24 hours in order to allow the water to eliminate the chlorine and to reach the temperature of the indoor environment.

If you can collect the rain water, this is a good alternative for watering the plants.

Regardless of the water source, this must be at the temperature of the environment where the plant is kept. Watering using cold water can lead to leaves falling off.

We cannot recommend an exact water quantity or the correct frequency as this highly depends of the environment’ temperature, air currents, the volume of the soil and of the plant’s foliage. The main rule to follow is that the plant’s soil needs to be slightly dry between 2 watering processes and a good water drainage must be assured so that base soil of the plant will not remain wet for long.


The plants need fertilizing as it helps the plant’s growth, flowering and fruit growth. Furthermore, growing the plants in a flowerpot makes the roots have access to a limited soil volume.

The wide range or fertilizers allows us to find the perfect fertilizer for each citric plant.

The frequency of fertilizing varies from one season to another.

In March, fertilizing the plant with a low nitrogen fertilizer is recommended as this is favors the flowering.

Starting with May, the plants can be fertilized weekely or once every 2 weeks. A NPK fertilizer is recommended, as it has a balanced macro-elements content, but one with micro-elements is also preferred.

Fertilizers which have micro-elements are important, especially the ones which have iron.

Starting with October, when the light intensity decreases, and the temperatures are lowering, the plant’s functions are slowed down, it is recommended to stop using fertilizers or applying them once every 1-2 months, depending on the condition of the plant and of the environment.

Moving the plant – the flowerpot and the correct soil

The plant must be moved from one pot to another usually once every 1-2 years.
citrus citrus pot

This is the recommended procedure when the vase no longer fits the plant and the roots of the plant have started to grow having the flowerpot’s shape. Another sign showing that the flowerpot must be changed is the plant’s roots which have started to one out of the flowerpot’s drain holes.

To check if the flowerpot is too small, place the plant in an inclined position, carefully remove the flowerpot and check if the roots have over-grown. If you want to easily take out the plant from the flowerpot, don’t water it for a few consecutive days.

The citric plants don’t like when the roots are moved or altered and if the plant is moved on time, this stress will not be inflicted on the plant. If moving the plant from one pot to another is delayed and the roots have over-grown, carefully remove the clump of soil near the roots so that these remain scattered. Cutting off the brown or dry roots is recommended.

Considering the fact that citric plants don’t like stagnating water in their soil, before pouring soil into the flowerpot, place a layer of rocks at the bottom of the flowerpot as it assures a good water drainage. Small pieces of old and broken ceramic flowerpots can also be used.

Moving the plants from one flowerpot to another must be done during the last days the winter. Pick a wider and taller vase, make sure it also has draining holes.

Be careful not to use a flowerpot which is too big, because the soil where the roots have not reached yet will remain wet for a longer period of time, leading to root rot.
citrus citrus changing the pot

The citric plants prefer a soil which is rich in nutrients, dank and which can assure a good water drain. You can use a special soil for the citric plants or you can combine peat, compost and perlite.

After the plant has been moved, the fertilizers must be applied only after a month, when the plant has accommodated to the new pot and soil.

Usually the plants which have been bought from stores have small flowerpots compared to the plant’s size and after buying the plant and allowing it to accommodate to the new environment, moving the plant to a bigger flowerpot is recommended.

If moving the plant to a bigger flowerpot is not convenient, changing the surface soil is recommended.

After moving the plant, it needs to be watered for a few consecutive days in order to maintain a dank soil.

Cutting the citric plant
citrus citrus cuts
The plants can be left to grow freely and if the shape of the plant’s crown is not suitable, you can cut it to adjust its shape. The best moment to perform these cuts is during spring, when the plant is moved outside.

The healthy sprouts, with a vertical growth can be cut if they have grown on the lower part of the crown or shortened if they have grown on the upper part of the crown. These cuts can be performed on mature plants.

If the plant has grown through grafting, any sprout grown from a graft can be cut.


In order to bloom, these flowers need a lot of sun and enough nutrients. Therefore, placing the plant in a sunny place and fertilizing it are necessary elements for blooming.
citrus citrus flower

Spending the winter in a lower temperature environment and rarely administrating water to the plant allows the plant to start its rest period, which is useful for blooming during spring.

The age of the plant plays an important role in blooming. Most plants need to be at least 4 years old in order to bloom.


The citric plants can reproduce by the seeds, by grafting, by cuttings, depending on the species and varieties. The plants which grew by seeds need grafting, otherwise they will bloom only after a long period of time. Reproducing by cuttings or by grafting, assures the growth of a plant which will bloom after 3-4 years. When using the cuttings method, a root stimulator, such as Razormin, can be used.

When grafting, mastic can be used to protect the existing wounds.

Spending the winter

This period is essential as it helps the plant go through a relative rest period so that the plant can bloom during spring. As autumn comes and the plant is moved back inside, the frequency of watering and fertilizing needs to be reduced, the plant needs to be placed in a sunny spot, preferably with a south exposure and the temperatures must be kept between 10-15 degrees Celsius. If, during nighttime, the temperatures drop a bit under 10 degrees Celsius, this is not a major problem, it can be recommended sometimes.

If the temperature of the environment exceeds 15 degrees Celsius, the plants need to be watered more often, but, as mentioned above, these temperatures do not favor the blooming process.

The citric plants don’t like air currents and they don’t have to be placed near doors or windows which frequently open.

Moving the plant inside-outside

The weather conditions from South-East Europe are suitable for growing these plants indoors during the cold season, but during the warm season, the plants must be taken outside, on a terrace so that they could benefit in full from the sunlight.

Be careful as taking out the plant and exposing it directly to the sunlight, during spring, can cause sunburns on the leaves, a problem which is encountered by all the species, regardless of their need for sunlight.

It is very important that, when moving the plant from the inside to the outside during springs, and vice-versa during autumn, a minimum amount of stress is inflicted to the plant. Otherwise, several health problems may occur, such as leaf, flower and fruit falling, a decrease in the plant’s growth rhythm.

To prevent the plant from suffering, it is important that the plant goes through the acclimantion process.  This is how the plant will get gradually used to the new light and temperatures conditions. Moving the plant outside during spring needs to be done when there no risks of temperatures below 10 degrees Celsius.

In the first days from moving the plant outside, it needs to be placed in a place where it can benefit from as much light as it can, but not directly into the sunlight. In the first day the plant will be kept for an hour under direct sunlight, after which it will need to be sheltered from the direct sun-rays. During the second day, you can keep the plant exposed to the direct sunlight for 2 hours, and then you need to shelter it from the direct sunrays. This technique must be used for 1-2 weeks as the plant needs to get used to the new conditions. If there are signs of sunburns even after the acclimation process, the plant needs to be moved to a shadowy place when the temperatures are high.

Considering the fact that the plant will have to be moved on a daily basis, you can ease this process by placing the plant of a wheel-base.

Applying Amalgerol as a fertilizer to the plant’s foliage, will help the plant overcome the stress inflicted by the moves.

Be extra careful with the quantity of water used to water the plant which has been moved outside because, due to high temperatures and air currents, the soil will dry out faster and the plant will need more water. The same rule must be respected: the first 3-5 cm cm of the soil can be dry.

If the outside temperatures drop under 10 degrees Celsius during nighttime, the plant must be moved back in for the night.

During autumn, it is the other way around: the plant must be placed in a shadowy spot in order to accommodate to lower temperatures and light, for 1-2 weeks. There is no need to move it on a daily basis if it benefits from enough light. The frequency of watering must be reduced. When the outside temperatures reach 10 degrees Celsius, the plant must be moved inside.
citrus citrus lemon tree indoors


Greasy Spot, caused by Mycosphaerella citri:

The disease is recognizable as yellow spots appear on the superior side of the leaves and big, orange to brown spots appear on the inferior side. Later on, the spots turn darker and have a moist aspect.
citrus citrus greasy spot
To prevent this disease, treatments using Score 250 EC, Topsin 500 SC, Dithane M 45, Bravo 500 SC, Polyram DF must be applied.

Sooty Mold, caused by  Capnodium:

This fungus grows on the sweet fecal matters left behind by aphids, greenhouse whitefly or fleas. Due to the growth of this fungus on the leaves, the processes of photosynthesis, sweating and breathing are affected  and the plant grows very slow or it stops growing. To fight this fungus, all the pests must be taken care of. The sooty mold can later on be taken off the leaves with a soft and moist fabric.

citrus citrus Capnodium

Spot Anthracnose, caused by Colletotrichum gloeosporioides:

Light colored spots, surrounded by a purple halo appear on the leaves. The spots which appear on the fruits have a darker color. This fungus generally grows on wounds created by other insects, or on sunburns or mechanical wounds.
citrus citrus Colletotrichum gloeosporioides
When the first symptoms of this disease are visible, treatments using Topsin, Dithane, Bravo and Polyram must be applied.


The most frequents pests which attack this plant are: the greenhouse whitefly, aphids, the European fruit lecaniums, the wooly apple aphids and the acari.

The presence of these pests can be easily seen with the naked eye.

Greenhouse Whitefly

This pest frequently attacks the interior plants and leads to a stop in those plants’ growth. The presence of the greenhouse whitefly is accompanied by “honey-dew” (its fecal matters).
citrus citrus greenhouse whitefly
Preventing this pest is not exactly an easy task as it grows a lot of generations in a short amount of time. It is recommended to alternate the pesticides to prevent the whitefly from being resilient to the active ingredients.


They usually stay on the growing tips, leading to leaf twists and a sticky mucous secretion of the leaves. Treatments using Actara, Mospilan, Decis Expert, Eforia, Fastac Active, Kaiso Sorbie, Faster, Karate Zeon and Movento can be used.

citrus citrus aphids

European fruit lecaniums and wooly apple aphids

These pests get settled on the plant’s stems and leaves and feed it its sap. They have a protective shield and in order to prevent their appearance the pesticides must be applied systematically and an adjuvant can be added, to help the mixture better be absorbed by the plant.

citrus citrus european fruit lecaniumscitrus citrus european fruit lecaniums 1citrus citrus wooly apple aphids


These small insects are visible as they leave a delicate web on the inferior side of the leaves. If the attack is severe, the web can be observed between the sprouts or at the base of the leaves. The leaves turn yellow and eventually fall off. Having in mind the fact that this pest grows several generations in a short amount of time, in order to prevent it, 2-3 consecutive treatments need to be applied, using: Nissorun, Novadim, Envidor, Vertimec, Milbeknock.
citrus citrus acari

Other problems

We are confronting, quite a lot, with problems which occur due to inappropriate environment or improper nourishment. These symptoms are often mistaken for diseases, but, most of the times we are dealing with malfunctions of the plant’s physiological processes.

Leaf Falling

This problem can be created by several factors, such as:

  • Too much or too little water;
  • A sudden change of temperature or light when the plant is moved;
  • Improper nourishment;
  • The presence of a disease or of a pest, but here you can see other specific symptoms;

During winter, the citric plants tend to lose a part of the leaves as a result of the relative air humidity or of the inappropriate environment conditions (temperature, light and water administration). Is reaction is not preferred, but it does not cause plant death and the plant will regenerate in the following spring. Most of the times, at the first signs of leaf falling, people make the mistake of over-watering and over-fertilizing, a bad decision which causes the plant to die.
citrus citrus leaf falling
When this problem can be observed, it is important to investigate and find out the cause of the problem which led to leaf falling.

Fruit falling

This can be determined by the lack of any of the above elements, or by a sudden temperature change or high variations of the soil’s moisture (too much humidity or too little).

Sun burns

These normally occur when the plant is moved to a sunny placed, without allowing the plant to go through the acclimation process. In this particular case, the leaf spots have a specific, light color. The tissues which have been burnt will no longer regenerate and it is highly recommended to remove the leaves which have these symptoms.
citrus citrus sun burns

Yellow leaves

A proper nutrition plays an important role in the plant’s growth and development. When one of these important elements is lacking, an imbalance will occur which determines the appearance of several problems.

Iron deficiency is common for citric plants and its symptoms are yellowing leaves between the veins, the area right near the veins remaining green. The symptoms can be seen from the tip of the sprouts. If the deficiency is severe, the base leaves will turn yellow as well.
citrus citrus iron deficiency

Nitrogen deficiency can be seen as total yellowing of the leaves, including vein bleaching and this process starts from the base leaves.
citrus citrus nitrogen deficiency

Shiny leaves

The citric plants have naturally shiny leaves, if the plants are well taken care of. Sometimes, a sticky fluid can be seen, called “honey-dew” and this fluid is associated with the aphid presence or the presence of the greenhouse whitefly. In order to prevent this problem, the pest presence must be taken care of and the fluid they produce can be wiped away with a wet cloth.

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