Avocados are certified favorites for people everywhere. The tree most likely originated from South-Central Mexico. Avocado trees are self-pollinating and are usually propagated through grafting, mainly to maintain the fruit quality and quantity. They are cultivated in tropical and Mediterranean climates and, like most plants, are also prone to conditions that cause yellowing leaves.
Avocado Leaves Turning Yellow: What Are The Common Reasons?
1. Due to overwatering
Avocado trees are used to sandy and loose soil, heavy rains and warm temperatures. They are native to tropical and subtropical environments, so cultivating them in cooler climates or rainy areas with clay soil could pose a problem. Avocado leaves are likely to turn yellow in these settings.
To avoid yellowing leaves, see to it that you provide sandy, well-draining soil. Deep watering is ideal; you should keep the avocado trees elevated on a mound or raised bed while providing at least four inches of water biweekly. Allow the soil to dry out between waterings.
Avocado trees have shallow roots, which could pose problems since shallow watering without proper drainage could lead to overwatering and root rot. Always fix the drainage before deep-watering the trees and see to it that the soil they are planted in is fast-draining.
How to prevent overwatered avocado trees:
- Keep the tree’s soil elevated by planting it on a raised mound or bed.
- Add perlite or sand to the top of the soil.
- Opt for mulching, because it has benefits such as better water retention, quality nutrients, weed prevention, and erosion resistance. For mulching, use leaves, bark or pine needles to improve the soil quality.
- Perform deep watering. To check when to deep-water your avocado trees, push a finger into the first two-to-four inches of soil to check if it is still wet, or use a moisture meter to check the deeper soil to about 10 inches deep.
2. Due to seasonal leaf drop or aging of leaves
Avocado trees usually shed some leaves around late spring to early summer, or from April to June. It is considered normal for leaves to turn yellow and fall off, since new green leaves will quickly grow to replace them. If you notice the yellowing of leaves around the months mentioned, there may not be much to worry about.
If you suspect there are reasons other than seasonal leaf drop, consider waiting at least one to two months to see if the leaves improve or if new leaves grow. If you have already fertilized the avocado tree, avoid fertilizing again. You may add mulch if you want to protect the soil and provide nutrients. Be sure to mulch the soil only if it is draining well.
3. Due to nutrient deficiency
Avocado leaves turning yellow could be attributed to nutrient deficiency. Avocado trees need nutrients like nitrogen, phosphorus and potassium and should be provided with fertilizers that contain these. Synthetic fertilizers are usually used in early spring while organic ones like compost are used every one to two months. The soil pH should also be checked to allow the nutrients to be absorbed properly.
Avoid fertilizing avocado trees from October to February, since they are dormant during these times and do not require nutrients to function. Other nutrients that tend to be deficient among avocado trees include iron and zinc.
Compost provides a complete set of the nutrients that avocado trees need. Be sure to combine with mulching to provide high-quality nutrients and increase the trees’ resistance to drought. To use both compost and mulch, provide the soil with one to two inches of compost and one to two inches of mulch on top. Do not touch the compost and mulch as it could introduce mold or disease, and keep it at least three inches away from the tree’s trunk.
Always maintain a balanced soil pH so the avocado trees can absorb nutrients properly. Avocado trees prefer a soil pH of 5 – 7. If your soil’s pH is too acidic, which is below 5, or too alkaline, which is above 7, you need to adjust the pH accordingly.
To increase alkalinity, add banana peels, wood ash and biochar. To increase acidity, add coffee grounds, sand and peat moss.
4. Due to pests or diseases
Another reason avocado leaves turn yellow could be the presence of pests or disease. Some tell-tale signs include cracking tree bark or oozing sap, small holes in the trunk, small bugs underneath the leaves, or sporadic brown or yellow spots. The possible culprits include mites and aphids, as well as fungal diseases. You can prune off the affected leaves and branches and burn them, or use organic insecticides like neem oil.
5. Due to insufficient sunlight
Avocado leaves could also turn yellow because of insufficient sunlight. Avocado trees, like most fruiting trees, prefer four to six hours of sunlight per day. If they get less than the required hours, they tend to develop yellow leaves due to a lack of chlorophyll. To correct this, the avocado trees should be in an area where they get a few hours of sunlight daily to maintain the healthy green color of their leaves.
Conclusion
Avocado leaves turning yellow is not so much cause for concern if it is due to seasonal leaf drop, which usually happens around April to June. However, yellowing leaves could also be attributed to other causes such as overwatering, insufficient sunlight, pest infestation or diseases.
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