Lemon trees are popular citrus trees that produce delicious, tart lemons. However, lemon tree owners often run into problems where the tree’s leaves start to curl or fold in on themselves. There are a number of possible causes for lemon leaves curling including pests, diseases, improper watering, and environmental stresses. Read on to learn more about the seven most common reasons why a lemon tree’s leaves may start to curl.
1. Spider Mites
Spider mites are tiny pests that can infest lemon trees and cause the leaves to curl and turn bronze. The mites suck sap from the undersides of leaves, damaging the plant tissue and causing leaves to shrivel up. Spider mite infestations often start in hot, dry conditions when the tree is stressed.
Signs of spider mites include:
- Bronzing, curling leaves
- Fine webbing on branches
- Speckling or stippling on leaves
- Frass or mite waste on leaves
To control spider mites, start by spraying the tree down with a strong jet of water to knock off some of the pests. Follow up by applying insecticidal soap or neem oil every 5-7 days for a few weeks. Make sure to coat the undersides of leaves where the mites like to hide. You can also introduce predatory mites that will feed on the spider mites.
Improving growing conditions and reducing water stress can also deter spider mites. Add mulch around the tree, provide shade if needed, and water consistently. Prune back any dead or heavily infested branches and leaves.
2. Aphids
Like spider mites, aphids are tiny sap-sucking insects that can infest lemon trees and cause curled, wrinkled leaves. Aphids tend to cluster on young shoots and the undersides of leaves, feeding on sap. As they feed, they secrete sticky honeydew which can then develop black sooty mold.
Signs of aphids include:
- Deformed, curled leaves
- Clusters of small, oval insects on shoots and leaves
- Sticky honeydew residue on leaves
- Sooty mold on leaves and branches
Blast aphids off the tree with a strong spray of water. Follow up by spraying insecticidal soap, neem oil, or horticultural oil every 5-7 days for a few weeks. Ladybugs and other beneficial insects will also prey on aphids.
Aphids thrive on stressed, unhealthy plants. Ensure the tree gets adequate water and fertilizer. Prune out heavily infested parts of the tree. Apply reflective mulch around the base to deter aphids.
3. Thrips
Thrips are tiny winged pests that can infest lemon trees and cause curled, distorted leaves. They use needle-like mouthparts to pierce the surface of leaves and suck out nutrients. This leads to silvery-brown scarring, spots, and downward curling of leaves. Thrips may also spread viruses.
Signs of thrips include:
- Curled, wrinkled leaves with scarring
- Small dark specks of excrement on leaves
- Damaged flowers and fruit
- Tiny yellow or dark winged insects on buds and leaves
Prune off damaged leaves and buds. Spray the tree thoroughly with insecticidal soap or neem oil to kill adult thrips and larvae. Apply sticky traps near the tree to capture the winged adults. Use reflective mulch and avoid over-fertilizing, as excess nitrogen can encourage thrips.
4. Leafminers
Leafmining larvae are the immature stage of insects including moths, flies, beetles, and sawflies. The larvae tunnel winding paths in between the top and bottom layers of leaves, eating out the insides. This causes the surrounding leaf tissue to curl and die. Leafminers are most common on young, tender flush growth.
Signs of leafminers include:
- Irregular serpentine mines in leaves
- Blotch mines or trails in leaves
- Curling, browning of leaves around mines
- Small holes in leaves where adult insects have emerged
Remove and destroy heavily infested leaves. Apply insecticidal soap or neem oil to suffocate adults and larvae inside mines. Use a systemic insecticide to poison leafminers as they feed. Keep trees healthy to deter leafminers which prefer young, succulent growth. Avoid excess nitrogen fertilizer which flushes susceptible new growth.
5. Lemon Leaf Curl Virus
Leaf curl is a viral disease that affects lemon trees, causing leaves to twist, curl, and become deformed. The virus is spread by the citrus psyllid, a sap-sucking insect that feeds on citrus trees. Leaf curl virus causes leaves to curl downward, pucker, become leathery, and develop yellow spotting or mottling. Severe infections can stunt tree growth and reduce fruit yields.
To test for leaf curl virus, look for:
- Downward curling and puckering of leaves
- Leathery, stiff leaves with enations or wart-like growths
- Yellow blotches and spots on leaves
- Stunted growth
- Presence of psyllid insects
There is no cure for leaf curl virus. Remove and destroy infected trees to prevent spread. Control psyllids by applying horticultural oil and spraying insecticidal soap. Do not move plant material from infected trees to healthy ones. Provide proper cultural care to keep trees healthy and less vulnerable to psyllids.
6. Nutrient Deficiencies
Improper soil nutrition can also cause lemon leaves to curl. Certain nutrient deficiencies interfere with growth, leading to distorted leaves.
Iron deficiency shows as yellowing between leaf veins while the veins remain green. It causes new leaves to be smaller and curled downward at the edges. Treat iron deficiency by spraying a chelated iron supplement on the foliage or applying an iron chelate to the soil.
Zinc deficiency also leads to smaller, wrinkled leaves with yellow spots and curling margins. Apply a zinc supplement or zinc chelate to deficient trees.
If leaves are curled and brittle with brown edges and tips, the tree may be deficient in calcium. Apply calcium nitrate or a calcium chelate via foliar sprays or soil drenches to restore calcium.
Before treating any suspected nutrient deficiency, test the soil to identify which nutrients are lacking. Improve the soil with organic compost to provide a range of essential nutrients.
7. Environmental Stress
Unfavorable growing conditions can also put stress on lemon trees and cause leaf curling. Some common environmental stressors include:
- Lack of water – Drought and inconsistent irrigation leads to moisture stress. Leaves will curl and fold inward to conserve water.
- Overwatering – Excess water deprives roots of oxygen. Leaves yellow and curl. Improve drainage and water deeply but infrequently.
- Extreme heat – Leaves curl to reduce exposure and minimize water loss. Provide shade, mist foliage, and mulch roots.
- Cold damage – Chilling injury causes wilted, curled leaves. Protect trees from frost and extreme cold.
- Strong winds – Causes moisture loss. Shelter trees from prevailing winds.
- Root damage – Damaged or restricted roots cannot take up water and nutrients properly. Check for root rot, girdling roots, or damage from soil cultivation.
- Light intensity – Too much or too little light leads to abnormal growth. Move tree or provide shade as needed.
Identify and remedy any cultural issues to take stress off the tree. Careful watering, pruning, fertilization, and pest control will help prevent leaf curling. Monitor for pests and diseases and treat any infections promptly. Address environmental stressors to restore optimal growing conditions. With proper care, lemon tree leaves should return to a healthy, normal shape.
Frequently Asked Questions About Lemon Tree Leaf Curling
Why are my lemon tree leaves curling inward?
The most common causes of lemon leaves curling inwards or downwards are water stress, high temperatures, low humidity, pest damage, viral infections, and nutrient deficiencies. Identify the underlying issue and take corrective action to resolve the problem.
What causes lemon tree leaves to curl and turn yellow?
Yellow, curled leaves can be caused by lemon leaf curl virus spread by psyllids, bacterial and fungal diseases like citrus canker, nutrient deficiencies, underwatering, root rot, and other abiotic stresses. Test for pathogens, improve growing conditions, and treat any infections.
How can I tell if my lemon tree has leaf curl disease?
Leaf curl disease causes thickened, leathery leaves that curl downward and pucker with yellow mottling. Leaves develop warty growths and fruit can be misshapen. Confirm diagnosis by testing for leaf curl virus. There is no cure so infected trees should be removed.
Why are my lemon tree leaves turning brown and curling?
Brown, curling leaves are typically a sign of underwatering, drought stress, salt buildup, root rot, or hot, dry winds. Boost irrigation frequency, improve drainage, repot with fresh soil, and provide wind protection as needed. Fertilize to encourage new growth.
Whatbugs cause lemon leaves to curl up?
Common bugs that curl lemon leaves include aphids, spider mites, leafminers, psyllids, thrips, and citrus bud mites. The piercing-sucking damage deforms leaf growth. Apply insecticidal soap or oil sprays to control populations. Remove badly damaged leaves.
Should I cut off curled leaves on a lemon tree?
Lightly curled leaves can recover, but severely curled, deformed leaves should be pruned off. Removing badly damaged foliage encourages new healthy growth and prevents pest infestations. However avoid overpruning, as excess pruning stresses the tree.
How do you treat curled leaves on citrus trees?
Identify and remedy the underlying cause, whether it be pests, disease, under watering, or environmental issues. Treat infections, improve growing conditions, and address deficiencies. Damaged leaves won’t recover but new growth should normalize with proper care.
Conclusion
Curled, wrinkled lemon tree leaves are often a sign of environmental stress or pest infestation. Common causes include spider mites, aphids, thrips, leafminers, leaf curl virus, nutrient deficiencies, drought, extreme heat or cold, and other unfavorable conditions. Identifying and addressing the underlying problem is key to restoring healthy growth. Remove damaged leaves promptly and take preventive measures like applying horticultural oil sprays. With diligent monitoring and care, lemon trees can thrive and produce an abundant harvest of bright, beautiful lemons for years to come.