How to Fix Yellow Leaves on Olive Trees (4 Ways)

We have an olive tree in our backyard and it’s starting to get yellow leaves. I wanted to learn more about this, so I did some more research. Here’s what I found.

Olive trees get yellow leaves due to factors like over-watering, nutrient deficiencies, pests, diseases, and environmental stress. To keep your olive tree healthy, ensure proper watering, provide the right nutrients, monitor for pests and diseases, and create a suitable growing environment.

Let’s take a closer look at why olive trees get yellow leaves and how we can fix it.

1. Improper Watering

Olive trees are native to Mediterranean regions, and they’re well-adapted to dry conditions. When I first started growing olive trees, I realized that they don’t need as much water as many other plants do. Over-watering can cause yellow leaves and even root rot.

To water your olive tree properly, let the top 2-4 inches of soil dry out between watering sessions. I like to use the finger test to check soil moisture – just stick your finger into the soil, and if it feels dry to the touch, it’s time to water.

Be sure to water deeply, so the moisture reaches the root zone. This encourages the roots to grow deeper and become more drought-tolerant. If your olive tree is in a pot, make sure there’s proper drainage to prevent waterlogging.

Another tip is to water your olive tree early in the morning, as this allows the water to slowly seep into the soil without evaporating too quickly due to the sun’s heat. This way, the roots have enough time to absorb the moisture before the day gets too hot.

2. Improper 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

When olive trees lack essential nutrients, their leaves can turn yellow. The most common deficiencies in olive trees are nitrogen, iron, and magnesium.

1. Nitrogen deficiency: Nitrogen is vital for plant growth and leaf production. A lack of nitrogen can cause the older leaves of your olive tree to turn yellow, and the tree may appear stunted. To address nitrogen deficiency, apply a slow-release, balanced fertilizer with an NPK ratio like 10-10-10, or incorporate nitrogen-rich organic matter like compost or well-composted manure into the soil.
2. Iron deficiency: Iron is necessary for chlorophyll production, which gives leaves their green color. Iron deficiency, also known as chlorosis, causes the leaves to turn yellow while the veins remain green. To correct iron deficiency, apply chelated iron to the soil or use a foliar spray. Keep in mind that iron deficiency can sometimes be a result of high soil pH, so test your soil and adjust its pH if necessary.
3. Magnesium deficiency: Magnesium is another essential nutrient for chlorophyll production. A magnesium deficiency can cause yellowing between the veins of older leaves. To remedy magnesium deficiency, you can apply Epsom salts (magnesium sulfate) to the soil or as a foliar spray.

The best fertilizer for olive trees is a balanced NPK or compost. Apply store-bought fertilizer as directed from the label, or 2 inches of compost every 1-2 months. To see which fertilizers I use and recommend, see my recommended fertilizer page.

3. Pests and Diseases

Pests and diseases can also cause yellow leaves on your olive tree. Here are some common conditions and how to deal with them:

1. Olive leaf spot: Also known as peacock spot, this fungal disease causes small, yellow spots on the leaves, which eventually turn brown and may cause leaf drop. To control olive leaf spot, prune your tree to improve air circulation and remove infected leaves. You can also use a copper-based fungicide or a homemade whey spray as a preventative measure.
2. Scales: These small, sap-sucking insects can cause yellowing leaves and leaf drop. Look for small, round, brown or white bumps on the leaves and branches. To control scales, you can release beneficial insects like ladybugs, lacewings, or parasitic wasps, which prey on scale insects. Alternatively, apply horticultural oil or insecticidal soap to suffocate the pests.
3. Aphids: These tiny insects feed on plant sap, causing leaves to curl, turn yellow, and become distorted. Aphids also produce a sticky substance called honeydew, which attracts ants and can lead to sooty mold. To manage aphids, release beneficial insects like ladybugs and lacewings or spray the tree with insecticidal soap or neem oil.
4. Verticillium wilt: This soil-borne fungal disease can cause yellowing and wilting of leaves, as well as branch dieback. There’s no cure for verticillium wilt, but you can try to prevent it by planting your olive tree in well-draining soil, avoiding over-watering, and maintaining good tree health. If your tree is affected, remove and destroy the infected branches to prevent the disease from spreading.

4. Environmental Factors

Environmental stressors can also contribute to yellow leaves on your olive tree, and it’s essential to consider various factors and how to address them. Temperature plays a significant role in the health of your olive tree, as they thrive in Mediterranean climates with warm summers and mild winters.

Exposure to extreme temperatures, either too hot or too cold, may cause stress, leading to yellowing leaves.

Protect your tree from temperature stress by planting it in a sheltered location, providing shade during the hottest part of the day, and using frost protection measures like frost cloth or a temporary greenhouse during cold snaps.

Sunlight is another critical factor for olive trees. They need plenty of sunlight to grow and produce fruit (usually 6+ hours a day), but excessive sunlight can cause leaf scorch, resulting in yellowing and browning of leaves.

If your olive tree is receiving too much direct sunlight, consider providing some shade during the hottest part of the day or planting taller companion plants to create dappled shade.

Soil conditions also play a significant role in the health of your olive tree. They prefer well-draining soil with a slightly acidic to neutral pH (between 6.0 and 8.0).

Poor drainage, compacted soil, or incorrect pH can all cause stress to your tree and lead to yellowing leaves.

Improve soil conditions by adding organic matter like compost or aged manure, loosening compacted soil, and testing and amending the pH if necessary.

Finally, if you’ve recently transplanted your olive tree, it may experience some stress, which can lead to yellow leaves. Minimize transplant shock by planting your tree in the appropriate season (usually early spring or fall), watering it consistently during the establishment period, and consider using a root stimulator to help the tree establish its root system.

Final Thoughts

Yellow leaves on olive trees can be caused by a variety of factors, including improper watering, nutrient deficiencies, pests, diseases, and environmental stressors.

To keep your olive tree healthy and prevent yellow leaves, ensure proper watering by allowing the top 2-4 inches of soil to dry out between watering sessions, provide the right balance of nutrients, and monitor for pests and diseases.

Additionally, create a good environment by considering temperature, sunlight, soil conditions, and minimizing transplant shock. By addressing these factors and providing your olive tree with the care it needs, you can enjoy a thriving, healthy tree in your garden!

Sources:

• https://www.oliveoilsource.com/page/site-selection
• https://cesonoma.ucanr.edu/files/27175.pdf

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