Olive tree leaves will turn yellow when the tree experiences major changes in its nutritional intake. The change in color can also be due to factors that cause stress to the plant.
The most common causes of yellowing olive tree leaves are watering problems, nutrient deficiency, insufficient sunlight, weather, transplant shock, disease and pests.
In this article, we will discuss the causes of yellowing olive tree leaves and how to remedy each one. So, if you are having this problem, keep reading.
Why are my olive tree’s leaves turning yellow?
Watering problems
The most common reason olive leaves turn yellow is overwatering. An olive tree’s roots can become waterlogged and deprived of oxygen if they are constantly soaking in boggy soil. This can lead to the roots rotting and deteriorating, which can affect the rest of the tree and turn the leaves yellow. Eventually, the leaves will start to droop.
You can tell the tree is overwatered when the yellowing of the leaves appears in a mosaic pattern and is not a consistent, solid yellow color. The leaves will also have brown tips that are crunchy, but they will not fall off easily.
To avoid overwatering, plant the olive tree in a pot that has adequate drainage holes. This allows the excess water to flow out when you accidentally overwater it.
Overwatering and rotting can also occur when the plant outgrows its pot, because the roots are crowding it. Transfer the plant to a larger pot with enough room for its roots.
Underwatering can also cause olive leaves to turn yellow. Plants need water to transport not only moisture, but also much-needed nutrients from the soil to the plant. If there is no water, the leaves that are considered least important are given the least resources. These are the leaves that eventually turn yellow. You can rewater the plant, but those compromised leaves cannot be salvaged and they will fall off.
Olive trees are very tolerant when it comes to changes in their watering schedules. It can take them several weeks before they show any signs of stress. So, if you see these signs, it probably means they are reacting to a change that has been ongoing for weeks.
You can remedy an underwatered olive tree by making sure you do not let the soil get dry between waterings. If the soil is dry to the touch, water the plant; if the soil is still moist, wait one or two days and check the soil again.
Nutrient deficiency
Olive leaves can discolor when they do not get enough iron or nitrogen. The leaves will also become pale in the absence of magnesium and zinc. Manganese deficiency affects the younger leaves first, while magnesium deficiency affects the older leaves.
Test the pH level of the soil around your olive tree before you make any adjustments. It could just be the soil’s pH affecting the transfer of nutrients into the plant.
Olive trees with a nitrogen deficiency will grow poorly and have yellow leaves, so nitrogen should be applied around the tree regularly. If the tree lacks iron, it can cause chlorosis, one of which symptoms is yellowing of the leaves.
Insufficient sunlight
If you keep your olive tree in the shade most of the time, or if you keep it indoors where it is unable to get all the sunlight it needs, it will not be able to photosynthesize properly. Plants need to be able to photosynthesize to produce chlorophyll, which is the substance that gives them their green color. Impaired photosynthesis will lead to the yellowing of the olive tree’s leaves.
Weather and seasonal changes
Olive trees, like most trees, will shed their leaves when winter comes. The leaves will turn yellow naturally and drop off. This leaf drop can also occur during other parts of the year, but to a lesser extent. If some yellowing happens and the rest of the tree looks healthy, then it is probably just a part of the olive tree’s growth cycle.
Transplant shock
Transplant shock is very common, especially for olive trees that were grown in a greenhouse or nursery. These places have the ideal conditions for the plant, so when you take it home with you, the sudden change in temperature, humidity and light can cause stress to the plant. Its leaves can turn yellow and fall off.
The only thing you can do in this situation is make sure you provide the plant with conditions that are as close to ideal as you can. Of course replicating a greenhouse in an ordinary home can be a daunting task, but as long as you simulate its natural habitat as much as you can, the olive tree will be able to adjust to its new conditions. Eventually, its leaves will retain their color and stop shedding.
Disease and pests
One of the most common diseases to infect olive trees is peacock spots. Peacock spots are caused by a fungus that leaves lesions on the leaves. This fungus proliferates more effectively during the growing season, and spreads from tree to tree via strong winds or insects.
You can use a fungicide to get rid of peacock spots.
Pests are also one of the most difficult problems to deal with when growing olive trees. They will suck the nutrients from the leaves and make the tree more susceptible to diseases and other pests. The most common types of pests on olive trees are spider mites, mealybugs, scale insects, whiteflies and aphids. They can also cause the yellowing of olive tree leaves if not eradicated in time.
You can use an insecticide to get rid of these pests. While doing any type of treatment on your olive tree, if you are able to move it to an isolated place, do so. This will help avoid the spread of any fungus or insects to your other, healthy, plants.
Conclusion
Olive tree leaves turning yellow indicates either a change in their nutritional uptake or an external stressor such as disease or pests. The best approach to treating yellowing leaves is identifying what caused the discoloration in the first place.
The most common causes of yellowing olive leaves are watering problems, nutrient deficiency, insufficient sunlight, weather, transplant shock, disease and pests.
Image: istockphoto.com / Adrian Vidal