Lemon Tree Leaves Curling | Causes and How To Fix

Along with being great landscape trees in USDA zones 9 to 11, lemon trees can be grown in containers in almost any climate. Regardless of where you grow them, however, they can be susceptible to leaf curl disease.

A leaf abnormality is usually a clear indication that something is wrong with your tree’s health or growing environment. If you notice curling leaves appear on your lemon tree, the last thing you should do is ignore them.

In this article, I’ll discuss the most common causes of lemon tree leaves curling and what steps you can take to fix the problem before things get worse.

What Causes Lemon Tree, Leaf Curl?

Curling leaves aren’t caused by one singular disease. Instead, they are a general sign that your lemon tree is under stress or otherwise unhealthy. You need to find the underlying cause of the curling leaves if you want to treat them.

Leaf curl can happen at any stage of growth, from juvenile through to mature trees. Some of the most common causes of curling citrus leaves include:

  • Watering problems
  • Extreme temperatures
  • Pest infestation
  • Disease
  • Nutritional deficiencies

Also, note that curling leaves may or may not be the only symptom your tree displays. Other symptoms — e.g., leaf discoloration, leaf drop, stunted growth — are often the easiest ways to distinguish one type of leaf curl issue from another.

How To Treat Curling Lemon Tree Leaves

Again, the most important step in treating lemon tree leaf curl is to narrow down what is harming your tree and causing it to decline in the first place. 

Below you’ll find the most likely explanations for curling leaves based on my personal experience. I’ve also offered some expert advice on diagnosing and treating these problems at their sources.

While my focus in this article is on the standard lemon tree, I want to point out that these symptoms and treatments can also be applied to most citrus varieties.

Drought Stress

Drought stress and curling leaves are so intertwined that I encourage every gardener to double-check their lemon tree’s watering needs before considering other potential causes. Leaf curl is usually the earliest sign of moisture problems, so this is your chance to nip the issue in the bud.

Lemon trees are adapted to warm, humid climates such as those found in the Mediterranean. As a result, they don’t hold up well in extended droughts.

Both landscape and container-grown lemon trees can fall victim to drought stress. Established in-ground trees can largely survive off of natural rainfall but require weekly watering if the weather is dry. Potted lemon trees should be watered before the soil dries out.

In addition to leaf curl, it’s very common for thirsty citrus trees — i.e., trees that have sat in dry soil for over a day — to suddenly drop their leaves the next time the tree is watered.

Temperature Shock

Leaf curling is a tree’s natural survival response to harsh temperatures. The leaves curl up to retain as much warmth or moisture as possible until conditions improve. Unfortunately, permanent damage is almost guaranteed once it gets to this point.

Outdoor lemon trees are innately more susceptible to temperature shock than those grown indoors. However, potted trees kept near cold drafts or indoor heat sources may experience these symptoms as well.

Cold Damage

Most gardeners know that citrus trees are cold-sensitive. But did you know that lemons are more easily damaged by cool temperatures than almost any other citrus variety?

Lemon trees enter dormancy when temperatures fall below 55°F. If temperatures continue to drop below freezing, serious damage or death is extremely likely.

Prevention is the best strategy. Insulate outdoor trees with blankets if cold weather is in the forecast. Move potted trees to a sheltered location or indoors until it warms back up.

Heat Damage

Lemon trees are also damaged by intense heat. Temperatures above 98°F often cause inward leaf curling. Dry conditions can make this response even worse.

For smaller trees, I recommend installing a shade net to protect the foliage during the hottest part of the day. Provide ample water during warm months. Water early in the morning to prepare lemon trees for afternoon temperatures.

Pest Infestation

Lemon trees play host to a number of pest species. While there are potentially dozens of pests that could be impacting your tree, only a couple of them are known for triggering leaf curl.

Taking good care of your citrus trees in the first instance is one of the strongest defenses against unwanted pest activity. Even if your lemon tree’s curling leaves can be blamed on an infestation, it’s a good idea to re-evaluate your maintenance routine or consider suitable companion plants for lemon trees, to help deter pests.

Citrus Leafminers

The citrus leafminer (Phyllocnistis citrella) is a very small species of moth. Its larvae live and feed on citrus foliage, producing visible tunnels in leaf tissues. While these tunnels are the primary sign of a citrus leafminer infestation, it’s also common for affected leaves to curl up. 

If you examine your lemon tree’s curled leaves and find distinctive white or brown trails winding over the surfaces, you have a leafminer infestation on your hands. Note that the larvae only target new foliage and will not tunnel through mature leaves.

Citrus leafminer damage is unattractive but rarely impacts overall tree health. Available pesticides are relatively ineffective. In fact, the University of California advises against using any pesticides because the citrus leafminer’s natural predators (which are also harmed by chemical treatments) are the most effective means of control.

damage caused by citrus leafminer
Damage caused by citrus leafminer

Sap-Sucking Pests

Sap-sucking pests are classified based on their feeding habits — they pierce plant leaf tissues and suck nutritious juices out. This group includes pests like aphids, spider mites, scale, mealy bugs, and broad mites. 

Damage from sap-sucking pests can trigger leaf curling because moisture is repeatedly removed from the tree’s foliage. Leading up to visible curling, you might also notice yellow or brown spots where the pests have pierced the tissue.

I recommend identifying the specific culprit behind the damage before taking steps to control the infestation. Some pests — e.g., broad mites — almost exclusively cause cosmetic damage. In most cases, such infestations are best managed with cultural practices. 

Most other pests can be controlled via Neem oil, insecticidal soaps, and other treatments. Avoid using chemical pesticides unless advised to by a professional. 

Disease

Fruit trees are frequently impacted by the disease, especially in regions where they are grown in commercial orchards or nurseries. Even if your area isn’t known for lemon production, keep in mind that citrus diseases often spread between varieties.

The disease can spread over long distances via the wind or running water. It’s also possible to infect healthy lemon trees by using contaminated tools and supplies.

Citrus Canker

Citrus canker, also known as bacterial blast, is a disease caused by the bacterium Xanthomonas citri subsp. citri

Since bacteria often enter through the damaged leaf tissue, citrus canker is frequently seen alongside pest infestations. Affected leaves develop visible lesions and curling within a couple of weeks of infection. 

While there is no cure for citrus canker, the good news is that the disease is not systemic. In other words, the bacteria won’t spread throughout the entire tree.

Controlling the spread of bacteria is essential to managing citrus canker. Inspect all new trees for signs of disease and clean gardening supplies after each use. If possible, plant outdoor lemon trees so that they are sheltered from the wind.

You can spray copper-based products on developing fruit every few weeks to keep the rinds disease-free. Unfortunately, this strategy doesn’t work on new leaf tissue.

leaves infected with citrus canker
Lemon Tree leaves infected with citrus canker

Citrus Scab

Citrus scab is a fungal disease characterized by raised pustules on leaves and developing fruit. It is caused by the fungus Elsinoe fawcetti.

The pustules typically form on the undersides of leaves in damp weather when temperatures are between 68 and 73°F. While these conditions seem incredibly precise, the disease can take hold surprisingly fast.

Chemical fungicides offer effective control when applied before symptoms emerge and continued through the growing season.

Nutrient Deficiency

Aside from leaf curl, yellowing foliage is also a recognizable symptom of a nutrient deficiency. 

Lemon tree fertilizer should be balanced or contain slightly more nitrogen than other macronutrients. Stay away from highly concentrated formulas with N-P-K ratios of 10-10-10 or more. Feed according to the manufacturer’s instructions and only during the growing season.

Of course, fertilizer applications aren’t always enough to deliver the nutrients lemon trees crave. If your tree’s soil is too acidic or too alkaline, it may be unable to absorb key nutrients. Lemons generally prefer a slightly acidic pH level of 5.5 to 6.5.

Potassium

Leaves with slight curling at the tip and yellow margins are indicative of a potassium deficiency. You might also see brown spots. 

Potassium is most readily available to plant roots when the soil pH is above 6.0. Overly acidic soil may cause potassium deficiencies. 

Zinc

Zinc deficiencies are incredibly common in citrus trees. Visible symptoms include stunted, bunched-up leaves that are yellow except for the veins. This discoloration often resembles zebra stripes.

zinc deficiency on citrus leaf
Zinc deficiency on citrus leaf

Boron

Boron deficiencies in lemon trees typically show up on the fruit rather than the leaves. However, potential symptoms include raised leaf venation and new foliage that curls or wilts.

FAQs Lemon Tree Leaves Curling

How Do You Know If a Lemon Tree Is Overwatered?

In lemon trees, overwatering causes symptoms like yellowing or drooping leaves. Lemon trees prefer well-draining soil and don’t like to be waterlogged. If left untreated, overwatering can lead to serious problems like root rot.

Citations

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Ben's horticultural interest grew when graduating from Hertfordshire University in 1997. Having contributed to numerous publications including Better Homes & Gardens, Garden Design Magazine, and The English Garden. He is also the author of Propagating Houseplants Made Easy.