While ants can usually become an unwanted nuisance in the home, they are beneficial insects in gardens. They represent an important part of the ecosystem. As a rule, they cause damage to young plants/trees at most. However, it usually leads them to fruit trees for a less acceptable reason, which requires swift action to protect the trees and fruits. The plant guide reveals what to do when and why.
Reason for ant infestation
When the Formicidae roam around the garden, it usually does not bother any amateur gardener or garden owner – usually the opposite is true. They spread seeds in nature, keep various pests out of gardens and aerate the soil. But when they rise in masses on a fruit tree, aphids and/or leaf fleas are usually behind it. Without them being on fruit trees, ant migration on trees doesn’t usually happen. Aphids and leaf fleas, which suck sap from fruit tree leaves, are excellent carbohydrate sources for Formicidae.
Aphids as donors for ant food
Selected by ant colonies are trees on which there are many aphids/leaf fleas. The reason is that they take their food through them. For this purpose they almost “milk” the aphids and leaf fleas. They love the sweet juice that the aphids as well as fleas take in via sucking out the leaves.
This preference for the sweet sap, and thus for the aphids and leaf fleas, goes so far as to transport falling aphids back up the trees. Often, it is also the industrious insects that intentionally bring the aphids onto a fruit tree. They even offer them protection for their predators. They care a lot that they are/remain numerous on a fruit tree so that their entire colony can find a delicacy in them.
Preferred fruit trees
Basically, all types of fruit trees can be attacked by ants if aphids or leaf fleas can provide them with food. But especially the cherry tree with sweet cherries is at risk. If there are aphids in the immediate vicinity, the industrious insects prefer to settle them on a cherry tree, even if an apple tree would be closer. This is explained by the particularly sweet leaves and flowers that a cherry tree has. Following this, the pear tree takes its position on the list of preferred fruit trees before the apple tree. They are also very fond of infesting orange trees, which spend the summer in tubs on the terrace.
If the trees are old fruit trees with an age of ten or more years, tree damage is usually not expected. However, it depends on how large the colony is and where it accumulates. Usually, they surround the trunk of the tree. Here they dig tunnels into the soil and, in the worst case, can expose the roots. As a result, the nutrient supply could be disturbed and the fruit tree damaged accordingly. However, death is hardly to be expected in old, large trees with strong, extensive root systems.
Young fruit trees
The situation is different for young fruit trees with still tender roots and meager leaf cover. Aphid infestation can cause leaf curling and wilting. The tree is weakened in growth, which has a negative impact on the next flowering and fruiting, especially on a cherry tree. In the worst case, the tree may also die because the aphids deprive it of all energy and/or insufficient energy can be absorbed by the soil tunneling and exposed roots.
There is no need to worry about the fruit on a cherry tree or other fruit trees, as ants will nibble on the surface of the fruit at most. Aphids/leaf fleas are confined purely to the leaf sap. When you harvest fruit, it should be washed as a matter of principle. In this way, the industrious insects are rinsed off. The fruit remains edible without restriction.
When to react to ant infestation?
In general, larger ant colonies should be removed from young eastern trees to prevent damage. In older specimens, intervention is only necessary in exceptional situations.
These are given if, for example:
- the hollow space caused by tunneling poses a risk of injury, such as a twisted foot
- the tree is weakened for other reasons
- the ants overflow to adjacent utility areas and disturb them, such as a terrace or sandbox
- damage to the tree is expected and/or flowering/fruiting is reduced.
- There are several ways to get rid of ants on a fruit tree and to control them permanently.
Insecticides are available in specialized stores that kill ants and aphids as well as aphids. This measure is not advisable, because you are interfering with the ecosystem in your garden. At the same time, if you use a chemical preparation, the harvest will be ruined or will no longer be safe to eat.
Basically, the starting point of a fight is always the ant burrow, which is located in the roots or near the fruit trees. In rare cases, an ant burrow can also be found on the tree trunk or in branches. Dousing the burrow with boiling water is effective, but only advisable if the burrow is farther from the trunk, otherwise the tree roots may be damaged.
Since not all ants are in the burrow, dousing several times over a few days is necessary to control all ants. In parallel, control aphids/leaf fleas to prevent them from attracting new ant colonies.
Special ant baits usually contain toxic insecticides that cause the crawling insects to die. Certain attractants are used to lure them into doses where they ingest the poison. There are different modes of action. Some act immediately and others only after a few hours. In the latter case, the ingested poison can also be passed on to the offspring. Ant baits should be placed close to the affected tree out of reach of small children and pets. To be effective, they must be placed around fruit trees for several weeks.
Because they are beneficial animals and valuable to nature, relocation is recommended instead of control.
Place double-sided tape around the trunk in the lower trunk area so that it completely breaks the ant trail and no other pathway is available other than through the tape. Some ants will venture onto the tape and stick. Most will relocate because the tape breaks the “scent trail”.
Similar to double-sided tape, the use of circles works. As close as possible, draw a bold chalk line around the trunk. This irritates the ants, taking away their scent trail and causing them to relocate.
You will have to be a little patient in driving them away by placing certain scents on the tree. They work best when laid out on the ground around the trunk of the tree. The more intense the scent, the faster the ants will be driven away. For this reason, you should change the scent source at least once a day – preferably in the morning and evening, so that the scent intensity is continuously kept high and makes the Formicidae retreat.
The most suitable scent sources include:
- Essential oils
- Cinnamon powder
- Lemon peel
- Wood wool
The most environmentally and animal-friendly relocation can be easily done yourself with the help of wood wool.
To do this, proceed as follows:
- Fill the clay pot with wood wool
- place it on the ant trail with the opening facing downwards
- the ants will consider the wood wool as a new burrow and will move to it
- after the “move” is completed, pick up the pot with a shovel without turning it over
- set the pot down in a more suitable place
- the new place should be at least 30 meters away from the tree
TIP: If you regularly spray your fruit trees with a strong jet of water, you can prevent an infestation of ants and aphids.