Tree Tomato: Tamarillo Tree Leaves Turning Yellow (Causes And Solutions)

If your tamarillo tree leaves are turning yellow and you want to know why, you’ve come to the right place. In this article, we look at the possible causes for yellowing tamarillo leaves (also known as the tree tomato) and provide solutions.

Tamarillo Tree Leaves Turning Yellow - Causes and Solutions - Tree Tomato
Yellow Leaves on Tamarillo Tree

Reasons a tamarillo tree leaves turn yellow include lack of fertilizer, growing in a cold climate, watering problems, disease such as powdery mildew, and pest attack.

Let’s look at each one in more detail with solutions you can use to fix yellow leaves on your tamarillo tree (botanical name Solanum betaceum).

Lack Of Fertilizer Can Cause Tamarillo Tree Leaves To Yellow

A lack of fertilizer can cause your tamarillo tree leaves to turn yellow. Hungry fruit trees will often show their unhappiness with yellowing leaves.

Tamarillo in a Pot - Tamarillo Tree Leaves Turning Yellow - Causes and Solutions
Tamarillo tree in need of fertilizer and repotting

The photo above shows a tamarillo tree grown in a pot. The leaves are just starting to yellow as a result of a lack of fertilizer. The tamarillo tree has used up the available soil nutrients and now needs to be transplanted into a larger pot or into the ground.

Tamarillo trees benefit from a seasonal feeding of an organic fruit tree fertilizer like this one.

Additionally, homemade compost spread around the base of the tree every month or so will keep the tamarillo tree happy and the soil healthy.

Climate Is Too Cold For Growing Tamarillo Trees

Tamarillo trees thrive in warm sub-tropical conditions.

Should outdoor temperatures drop below 26°F (-3°C), your tamarillo tree leaves can yellow, before the tree completely fails. Cold temperatures can be fatal to a tamarillo tree.

So if you live in a climate with cold winters, consider growing tamarillo trees in pots whereby they can be moved indoors during the winter.

Tamarillo trees can be kept pruned to 6.5 feet (2 meters) to keep them manageable for growing in pots and containers.

Watering Issues Can Turn Tamarillo Tree Leaves Yellow

Watering your tamarillo tree is important but it’s easy to give too much water and sometimes too little.

The best way to determine the right amount of water for your tamarillo tree is to keep an eye on your tree’s health. If it looks happy and healthy, then sick with your water regime.

On the other hand, if your tamarillo tree leaves are turning yellow, consider if you are overwatering or under watering your tree.

Overwatering Tamarillo Tree

Overwatering your tamarillo tree can cause the leaves to turn yellow.

Tamarillo trees prefer free-draining soil where they can dry out a bit between watering. So if you think this could be the cause of your tamarillo tree leaves yellowing, cut back on some of the watering.

For tamarillo trees grown in pots, ensure there are adequate drainage holes and consider removing any saucer designed to catch the water. This of course only relates to an overwatering issue. In other circumstances, a saucer might be an excellent idea.

Overwatering can also lead to other diseases such as root rot, so monitor your watering level, keep an eye on your tree’s health and adjust the watering as necessary.

Under Watering Tamarillo Tree

Conversely, under watering your tamarillo tree can cause its leaves to turn yellow. As well as turning yellow, leaves will appear brittle, due to drying out. In this instance, leaves will likely progress to a brown color before falling off the tree.

Tamarillo trees have shallow roots that can dry out quickly. So while they don’t like to sit in soggy water-logged soil, they do need regular watering.

In very warm weather your tamarillo tree will benefit from watering every day or so. In cooler weather watering can be reduced. But remember, the tamarillo tree roots are fairly shallow, so they have a tendency to dry out quicker than fruit trees with deeper roots.

Ensure the soil is free-draining and keep the tree roots protected with mulch to stop the soil from drying out. Just be mindful of keeping mulch off the trunk which can otherwise encourage trunk rot.

Disease: Powdery Mildew Can Cause Tamarillo Tree Leaves To Turn Yellow

Tamarillo trees can be affected by powdery mildew which in turn leads to yellow leaves. Powdery mildew can grow and spread on the tamarillo tree leaves, branches and even the flowers. It will show up as a powdery white coating which can sometimes look a little gray in color.

Powdery mildew on tamarillo trees can be caused by high humidity, low air circulation and overcrowding of trees and plants. So be sure to give your tamarillo tree enough room to grow. Ideally, tamarillo trees should have 6-10 feet (1.8-3 m) of space between trees.

Consider pruning a few branches if you think the tree is particularly dense to open up the airflow.

Natural and organic solutions for treating powdering mildew on tamarillo trees include a DIY milk spray that acts as a natural fungicide or you can use an apple cider vinegar solution.

You can find our recipe for Powdery Mildew Milk Spray here.

And for the apple cider vinegar spray, mix 3 tablespoons of apple cider vinegar with a gallon of water. Spray the tamarillo tree where you see the powdery mildew. A vinegar with low 5% acetic acid (sold in supermarkets) is recommended so as not to risk burning the plant.

Remove any fallen leaves to prevent the spread of powdery mildew.

Pest Attack Cause Tamarillo Tree Leaves To Turn Yellow

While tamarillo trees are fairly hardy, they can suffer from pest attacks. Of these pests, it is aphids that can cause tamarillo tree leaves to turn yellow.

Aphids on Tamarillo Tree Leaves - Tamarillo Tree Leaves Turning Yellow
Tamarillo Tree Leaves infested with aphids and ants (remnants of suds from soapy spray treatment)

With a particularity bad aphid infestation, such as the one in the photo above, you may notice the addition of ants. The symbiotic relationship between aphids and ants refers to their mutually beneficial partnership. The ants protect the aphids from other predators while feeding off the aphid secretion which is sweet and known as honeydew.

If the aphid infestation is mild with no evidence of ants, spray the leaves with water to get rid of the aphids. Repeat over a few days. The addition of a mild dish-washing liquid mixed with water in a spray bottle also works well. Avoid spraying in the hottest part of the day.

Encouraging beneficial insects into the garden can also naturally get rid of aphids. Ladybugs and lacewings fed off aphids and will help control and eliminate them.

The addition of ants could mean the aphid infestation is a bit more serious. If you have already tried the above techniques without success, you can use horticultural neem oil such as this one, which will treat the problem naturally and organically.

Healthy Tamarillo Tree Leaves

If you are unsure as to what healthy tamarillo tree leave should look like, here are a few photos.

Healthy Tarmarillo Tree Leaves
Healthy Tamarillo Tree Leaves
Healthy Tamarillo Tree Leaves and Fruit - Tree Tomato
Healthy Tamarillo Tree Leaves and Fruit Still Ripening


Once you determine the reason your tamarillo tree leaves are turning yellow, you can commence remedying the problem. Acting early should result in a successful recovery whereby you can expect a flourish of new growth and a bountiful harvest of tamarillo fruit!