How to Fix Curling Leaves on Olive Trees (3 Ways)

Our olive tree had some dropping and curling leaves recently and we weren’t sure what was causing it. We checked online, but couldn’t find a great resource. So, we did some more research and put together this guide. Here’s what we found.

Olive trees get curled leaves due to pest infestations, water stress, nutrient deficiencies, or diseases. To fix curled leaves, identify the cause, apply proper watering practices, provide balanced nutrition, and use organic pest control methods like neem oil or introducing beneficial insects.

Let’s take a closer look at exactly how to identify the issue, and how to fix it.

Identify the Cause

To fix the problem of curled leaves on your olive tree, we’ll first need to identify the root cause. There could be several reasons for the curling leaves, such as pest infestations, water stress, nutrient deficiencies, or diseases. Here are some tips to help you diagnose the problem:

1. Examine the leaves and look for any other signs of distress, such as yellowing, spots, or the presence of pests or their residue. This will help you narrow down the possible causes.
2. Check the overall health of the tree. Is it growing well, producing fruit, and showing healthy new growth? If the tree is otherwise healthy, the problem might be isolated and easier to address.
3. Observe the environment around the tree. Are there other plants with similar issues? This could indicate a more widespread problem like a pest infestation or disease.
4. Review your tree care practices, including watering, fertilizing, and pruning. Incorrect practices can stress the tree and make it more susceptible to problems like curled leaves.

Once you have gathered this information, start ruling out potential causes. Here’s a breakdown of some common reasons for curled leaves in olive trees and how to recognize them (we’ll expand on these topics further below).

• Pest infestations: Pests like aphids, scale insects, and mites can cause leaves to curl by sucking sap from them. You might see the pests themselves or signs of their presence, like honeydew (a sticky, sugary substance) or sooty mold growing on the leaves.
• Water stress: Both over-watering and under-watering can cause curled leaves. If the soil is constantly wet or very dry, the tree may be experiencing water stress. Olive trees prefer well-draining soil and don’t like to have “wet feet.”
• Nutrient deficiencies: A lack of essential nutrients, such as nitrogen, phosphorus, or potassium, can cause curled leaves. If the tree is showing other signs of nutrient deficiency, like yellowing or stunted growth, you may need to address its nutritional needs.
• Diseases: Some diseases, like olive leaf curl or peacock spot, can cause leaves to curl. Look for other symptoms of disease, such as spots, lesions, or discoloration on the leaves.

Now, let’s take a look at more details about these common issues and how to fix them.

1. Improper Watering

Olive trees are relatively drought-tolerant, but they still need proper watering to thrive. Over-watering and under-watering can both cause curled leaves. Here are my best tips to successfully water olive trees.

• Monitor soil moisture: The best way to water an olive tree is to only water when the first 2-4 inches of soil is dry. I check this by pushing my finger into the soil. Soil moisture should be similar to a wrung-out sponge. This practice helps prevent over-watering and root rot.
• Water deeply and infrequently: When you do water your olive tree, make sure to water deeply to encourage a strong and healthy root system. It’s better to water thoroughly once a week rather than providing small amounts of water daily. This approach mimics the tree’s natural environment and reduces the risk of water stress.
• Use proper drainage: Olive trees prefer well-draining soil, so make sure your tree is planted in an area with adequate drainage. If you’re growing your olive tree in a container, make sure the pot has drainage holes, and consider using a well-draining soil mix.
• Adjust watering based on the season: During hot and dry periods, your olive tree may require more frequent watering. Conversely, during cooler and wetter months, you may need to water less frequently. Keep an eye on the weather and adjust your watering schedule accordingly.

So, after only watering when the top 2-4 inches of soil is dry, I recommend applying 2 inches of compost every 1-2 months and 4-12 inches of mulch every 3-6 months. These amendments dramatically improve soil nutrients, the soil’s drainage (both fast and poor), and promote beneficial soil life.

However, if you’ve checked your soil and found the top 2-4 inches are dry in between watering, what could be the issue then?

2. Nutrients

Nutrient Deficiency	Leaf Symptom
Nitrogen	Entire leaf is pale or yellow
Iron	Dark green veins, rest of the leaf is yellowing
Zinc	Yellow blotches
Manganese	Broadly pale leaves, foliage color looks mottled or smeared

Just like us, olive trees need proper nutrition to maintain their health and avoid issues. When olive trees lack nutrients, they can become stressed and develop problems such as curled, yellowing, or dropping leaves. Poor nutrition may also affect fruit production and overall tree growth.

On the other hand, too much nutrients, often caused by over-fertilizing, can lead to root burn and stress the tree. In extreme cases, excess nutrients can cause leaf browning and even the death of the tree. To avoid these issues, it’s essential to provide balanced nutrition to your olive tree.

One way to provide balanced nutrition is by using compost. Compost can help improve soil quality, balance soil pH, and provide a steady supply of essential nutrients. For olive trees, a 2-inch layer of compost applied around the base of the tree every 1-2 months works well.

If you choose to use a store-bought fertilizer, I recommend avoiding chemical fertilizers whenever possible.

Although they may provide short-term benefits, chemical fertilizers can lead to long-term issues such as drying out the soil and killing beneficial soil life such as mycorrhizal fungi.

Mycorrhizal fungi promote many aspects of plant life, in particular improved nutrition, better growth, stress tolerance, and disease resistance.

Department of Biology, University of Fribourg, Switzerland

Instead, choose organic fertilizers that provide the necessary nutrients, including nitrogen, phosphorus, and potassium (NPK), as well as secondary nutrients like iron, zinc, and magnesium.

To see which fertilizer I use and recommend, see my recommended fertilizer page.

Imbalanced Soil pH

Olive trees prefer a soil pH between 7.0 and 8.0, which allows them to absorb nutrients effectively. If the pH is outside this range, the tree might struggle to take up nutrients, leading to issues like curled leaves.

Fourteen of the seventeen essential plant nutrients are obtained from the soil. Before a nutrient can be used by plants it must be dissolved in the soil solution. Most minerals and nutrients are more soluble or available in acid soils than in neutral or slightly alkaline soils.

Donald Bickelhaupt, SUNY College of Environmental Science and Forestry

To check your soil pH, you can use pH strips or a pH meter. If you need to adjust the pH, use appropriate amendments like lime (for acidic soil) or peat moss (for alkaline soil).

3. Pests

Pest infestations are another common cause of curled leaves in olive trees. Aphids, scale insects, and mites can all cause leaf curl by sucking sap from the leaves. To protect your tree and prevent curled leaves, consider using organic pest control methods. Here are some options:

• Neem oil: Neem oil is a natural, organic insecticide that can help control a variety of pests, including aphids, scale insects, and mites. To use neem oil, mix it with water according to the label instructions and spray it on the affected areas of your olive tree.
• Insecticidal soap: Insecticidal soaps are another organic option for controlling pests on your olive tree. They work by dissolving the outer layer of the pests, causing them to dehydrate and die. To use insecticidal soap, mix it with water as directed and spray it on the infested areas of your tree.
• Introducing beneficial insects: Some insects, such as ladybugs and lacewings, are natural predators of pests like aphids and mites. By introducing these beneficial insects to your garden, you can help control pest populations and protect your olive tree from curled leaves. You can purchase beneficial insects from garden centers or online retailers.
• Regular monitoring and manual removal: Regularly inspect your olive tree for signs of pests and remove them manually when possible. This may include wiping off scale insects or blasting aphids off with a strong stream of water (this is what worked for my lime tree). By staying alert, you can catch infestations early and prevent them from causing curled leaves.
• Encourage a healthy ecosystem: A diverse and healthy garden ecosystem can help naturally control pest populations. Plant a variety of flowering plants to attract beneficial insects and consider providing habitats, such as insect hotels, to encourage their presence in your garden.

Sources

• http://www.santacruzolive.com/planting.php?page=lime
• https://ipm.ucanr.edu/agriculture/olive/

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