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Why Do Lemon Tree Leaves Curl and How to Fix It

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Leaves on lemon trees may curl for several reasons, including poor soil, poor watering habits, or the shock of a new environment. Humidity also plays a role.

Common good plant husbandry can prevent most lemon leaves from curling, but pests and diseases may also be the cause. Insect pests like red mites or purple mites, leafminers, and aphids can cause citrus leaf curl and various fungal diseases or bacterial infections.

What is Citrus Leaf Curl?

Lemon tree leaf curl is a condition that causes the leaves of lemon trees to curl up or become scrunched up. The leaves may also turn yellow or brown and eventually drop off. These are all signs that your citrus tree is in distress.

There are several reasons why lemon tree leaves are curling, including:

  • Pests
  • Diseases
  • Nutrient deficiencies
  • Compromised root health
  • Water mismanagement
  • Temperature extremes

Common Causes of Lemon Tree Leaves Curling

Pests

Lemon trees are susceptible to pests that can cause their leaves to curl. Common pests that attack lemon trees include citrus leaf miners, mites, aphids, spider mites, scales, and Asian citrus psyllids (tiny pests much like aphids)

Insect infestations typically decrease as leaves mature, but they can concern young trees or lemon trees that consistently produce new growth. A heavy pest infestation can result in curled and distorted leaves.

If your citrus leaves are curling, check their undersides for tiny pests feeding in groups. Insect infestations should be treated with neem oil or insecticidal soap weekly. 

Beneficial insects can control citrus leaf miners and mites, or neem oil is applied weekly. Be cautious in using insecticides, as these can help insects develop resilience.

The citrus leaf miner leaves behind white or yellow lines in the shape of a serpent on the green surface of their host plants, betraying their presence.  They can be difficult to treat, but citrus trees can survive an average infestation.

A spider mite infestation can be identified by little yellow spots and leaves curling.

Spider mites thrive in the drier conditions of homes and are more abundant indoors, where they frequently attack lemon plants brought inside for the winter.

Since spider mites hate humidity and wetness, periodically misting the leaves is an excellent method for dispersing them. An additional highly efficient therapy is to spay the leaves with soapy water.

When you see signs of pests on your fruit tree, it’s important to take the right action immediately. The sooner you get rid of the pests, the better chance your lemon tree will have of recovering. 

By removing any seriously damaged branches, the tree should recover.

Citrus Tree Diseases

Several diseases can cause citrus tree leaf curls. Citrus trees are susceptible to fungal diseases, bacterial infections, and virus infections that cause curling leaves. 

Common diseases that make lemon tree leaves curl:

Bacterial Blast or Pseudomonas syringae

Bacterial blast, also known as the citrus blast, is a fungal disease affecting citrus plants and is caused by bacteria entering lemon tree leaves through wounds caused by wind damage or insect feeding sites. 

Citrus blasts can be prevented by planting trees with adequate wind protection. Remove any diseased or dead branches as soon as they are identified.

Anthracnose or Colletotrichum gloeosporioides

While this disease does not cause lemon tree leaf curl, it does cause leaf drop and is a serious disease to watch out for. It is more common on lemon trees grown outdoors in seasons with high spring rainfall. 

Your potted lemon trees should be safe as Anthracnose infections rarely affect lemon trees grown indoors. 

If your lemon tree is already infected, you can treat it with a copper fungicide. Please be cautious when using any controlled product, following directions in the container to the letter. 

When treating lemon tree leaves curling caused by a fungal disease, it is important to do it as soon as possible. The sooner you treat the disease, the better.

Black Root Rot caused by Thielaviopsis basicola

Root rot is commonly found in potted lemon trees that offer poor drainage or compromised root health caused by inadequate lighting. I cover root health in more detail later in this article.

Nutrient Deficiency

Like most fruit trees, lemon trees need certain nutrients to stay healthy and productive. When lemon trees are deficient in these nutrients, it can cause curling leaves, chlorosis (yellowing), or necrosis (leaf dying).

Heavy feeders like lemon trees need to be fertilized frequently during the spring and summer to ensure they get the nutrients they need to thrive and produce the best fruit and blossoms.

The leaves may curl, droop, turn yellow, and even fall off if the plant is stressed due to a lack of nutrients.

Plants in containers are more likely to suffer from nutritional deficiencies, especially if they have been growing in the same container for an extended time.

Curling leaves can be a symptom of a nutrient shortfall, and insufficient soil magnesium or potassium are possible culprits. Curled leaves that turn inward indicate a magnesium deficiency, whereas downward-curling leaves point to a potassium deficiency.

Curling leaves are one symptom of nutritional deficiency, which can also cause the leaves to droop and turn yellow.

The quality of your soil can be evaluated by sending a sample to a lab, which you can do at any time. Feedback will include soil pH results (ideally, between 6.0 and 7.0).

You can also apply a citrus fertilizer to compensate for the lack of nutrients.

Application of fertilizer once a month throughout the spring and summer should help the lemon tree’s leaves, which had previously appeared curled, to straighten up.

 Excessive fertilizing can also cause curling leaves, as can an unbalanced diet.

Magnesium, potassium, iron, and zinc are the most common nutrient deficiencies that cause lemon tree leaves to curl. Excessing include boron.  Leaves curl and become yellowish (chlorosis) if 2,4-D is incorrectly applied to manage fruit drop and fruit size.

When the lemon tree leaves curl more inwards, this is an indication that your lemon tree has a magnesium insufficiency. At the same time, a potassium deficiency will induce the lemon tree’s leaves to curl down at the tip.

To remedy these deficiencies, lemon trees need to be fertilized with a specially formulated fertilizer for citrus trees. This way, they will be getting the right amount of nutrients they need. 

Be sure to follow the manufacturer’s instructions on fertilizing your lemon tree.

Compromised Root Health In Fruit Trees

While citrus trees need regularly watered, too much water can cause curling leaves. When lemon tree roots are constantly wet, it can lead to root rot and several other problems.

Lemon trees need well-draining soil to avoid lemon tree leaves curling from too much water. If you think your lemon tree is being overwatered, check the drainage around the plant. The soil should be moist but not soggy.

To fix the problem, let the soil dry out completely before watering your lemon tree again. You may also need to report your lemon tree into a pot with drainage holes to help improve drainage.

Water Management in Citrus Trees

Drought stress is one of the most common reasons lemon tree leaves to curl. When the roots of lemon trees don’t have enough water, it causes a lack of nutrients and water to reach the leaves, leading to shriveling and leaf curling.

When your lemon tree’s leaves curl in on themselves while remaining green, it might be due to insufficient watering.

The first step is to check the soil moisture around your citrus tree. If it is dry, give your lemon tree a deep watering, making sure to wet the roots.

You can also mulch around your lemon tree to help retain moisture in the soil. This is especially important during hot, dry weather.

If you have an indoor Meyer lemon tree in a pot, check the soil moisture more frequently, as potted plants can dry out quickly and are more prone to drought stress. 

Also, be sure to water your lemon tree with room temperature water, as cold water can shock the roots and cause a leaf curl.

Most lemon trees do best with regular, deep waterings once a week after letting the top two inches of soil dry out between waterings. 

Leaves will curl on a lemon tree if you water them too little since the water won’t reach the roots.

Compared to the soil in garden borders, the earth in pots dries out rather quickly. There is a direct correlation between the reduced capacity for soil and water in pots. 

Furthermore, lemon plants necessitate full light, which might hasten the drying of pots and increase the severity of drought.

Once you have corrected the watering issue, the lemon leaf should stop curling.

Ensure lemon trees are watered deeply and regularly during the hot, dry summer months to prevent drought stress. Check the soil moisture around your lemon tree before watering to avoid overwatering.

Temperature Extremes

Lemon trees are tropical plants and prefer warm weather. When lemon trees are exposed to cold temperatures, it can cause curling citrus leaves. If you live in an area with cold winters, you’ll need to take steps to protect your fruit trees from the cold.

One way to protect lemon trees from cold weather is to cover them with a frost blanket or burlap. This will help to insulate them and prevent the leaves from freezing. Shade cloth is ineffective.

You can also move your lemon tree indoors during the winter months. Place it in a sunny spot near a window to protect it from the cold.

If your lemon tree is exposed to temperatures below freezing, the leaves will turn brown and die. If this happens, you can cut off the damaged leaves, and new growth should appear in the spring.

Too-warm temperatures can also cause citrus leaf curls. In the summer, excessive heat can cause the plant to become dehydrated and curl its leaves due to a lack of water.

Simply relocate your lemon tree to a shaded location if its leaves curl up during hot weather. To counteract the soil heat, add mulch around your plant. Watering your citrus plant more frequently in summer will help them recover.

Humidity

Lemon trees thrive in warm, humid temperatures. The leaves of a lemon tree within a home or office building are constantly being robbed of moisture by the dry air from the HVAC system, the fireplace, and other radiators or fans. 

In response, the lemon tree’s leaves curl inward to prevent water loss. As a result, lemon trees frequently shed some of their leaves.

Several heat sources cause temperature variations, and heating the house is a typical wintertime activity. 

As a result of the stress brought on by the daily cycle of temperature change, a lemon tree may exhibit curled leaves. Increased evaporation from the soil due to heat sources causes the plant to dry out, resulting in withered leaves.

Indoor lighting is reduced. When brought indoors, lemon trees often suffer from stress due to the sudden change to the lower light levels they are accustomed to outside.

When you bring your lemon tree indoors, the temperature and humidity levels are likely to be somewhat different from that outside, which might cause the leaves to curl as a protective mechanism. 

Leaves curl because of abrupt and significant changes in environmental factors like temperature.

In Closing 

Lemon leaves curling can be caused by many things, including pests, overwatering, or fungal diseases. The best way to prevent lemon tree leaves from curling is to keep an eye on your plant and take action as soon as you see any signs of problems. 

With a little care, you can keep your lemon tree healthy and looking its best!