Japanese maples are one of the most requested trees when it comes to yard decoration. But pests are sometimes a serious problem for owners of these trees.
To get rid of bugs on a Japanese maple, spray the leaves with an insecticide soap. Also, remove severely infested leaves and branches. In some cases, a systemic pesticide should be used.
This is a short recommendation for removing pests from your tree. Next, we’ll look at the most common insects that can damage Japanese Maple and ways to control them.
I also recommend you read How to Grow Japanese Maple Trees. In this article, you will find a lot of useful information and tips that actually work.
The first most common pest of Japanese maple is aphids. They are miniature insects that have an elongated body of white, gray, or greenish color.
They make a living by piercing the soft tissues of the tree and extracting the sap from there. As they live, they secrete a sticky substance that ants are very fond of.
Aphids can be found on young leaves, leaf petioles, and unripe branches. They cause the leaves to curl and turn brown. These pests can greatly ruin the appearance of a maple tree, but it will not kill it.
- If there are few aphids, wash them off with water from a garden hose or crush them with your fingers.
- If heavily spread, spray the leaves with insecticidal soap. Repeat spraying after 2 weeks.
- Avoid using neem oil as it can burn the delicate leaves of the Japanese Maple.
- Another way is to spread ladybugs over the maple. Ladybugs are natural enemies of aphids and are commercially available. Avoid using insecticidal soap in combination with ladybugs.
Caterpillars of various beetles often cause damage to the leaves of Japanese Maple. Sometimes the damage can be quite severe and it is not always possible to notice the pests because some of them are active at night.
Caterpillars usually eat the soft young leaves at the top of the crown. The leaf may be badly eaten but the veins will remain intact.
- Collect the caterpillars and discard them away from the yard.
- Buy Bacillus thengiensis and spray the leaves. This bacteria kills the caterpillars and is totally environmentally friendly.
- Spray the leaves with an aqueous insecticide solution if the previous methods didn’t work.
Scale is the most undesirable pest of Japanese maple because it is quite difficult to deal with. If you have this pest in your garden, get ready for a long struggle.
The scale has a rounded body that is hidden under a tough shell. These insects hardly move around. As soon as a young specimen finds a place, it bites into a branch and so spends its entire life.
Usually, these insects settle on young branches that have not yet hardened. They feed on the sap of the tree, which can cause the leaves to turn brown around the edges and curl.
- If the insects are few in number, scrape them off the branch and throw them away farther from the garden.
- If this pest is widespread, spray Japanese Maple with insecticidal soap several times in the second half of summer and fall. This will kill the young as they move from their cocoon to a new location.
- Another way is to use beneficial insects such as wasps. But in this case, do not use insecticide.
Weevils are also pests of Japanese maple. These beetles are capable of destroying a large number of cultivated plants, and unfortunately, maples are no exception.
The body of the weevil is larger than that of, for example, aphids. They have an elongated head and body. The color can be black, brown, or dark gray. They have six legs and no wings.
They are capable of damaging a large part of the leaf blade. Very often they nibble on the leaf edge or holes in the leaves.
- Replace the mulch around the maple with fresh mulch because the old mulch may contain weevil eggs.
- Spread beneficial nematodes in the soil around the maple. The nematodes will kill the larvae and interrupt the reproduction cycle of the weevil.
- Spray maple leaves with pesticides to get rid of the adult beetles.
Asian Ambrosia Beetles
The Asian ambrosia beetle is quite an insidious creature. They do not eat Japanese maples themselves, but their activity can cause fatal damage.
When the female is looking for a place to lay her eggs, she drills into the branches or trunk of Japanese maple. There she lays her eggs, which eventually hatch out.
Neither she nor the larvae eat the tissue of the tree. Instead, the beetle carries the spores of ambrosia fungus. The fungus begins to grow in the holes and kills the tree.
The symptoms are browning and shriveling of the leaves. A white cotton-like substance may also be visible from the holes.
- If you see holes in the branches, cut them off a few inches below the holes. Burn the cut branches.
- If skeletal branches or trunk are damaged, spray the holes with a contact insecticide. Make sure the insecticide gets into the holes.
- If white cotton appears from the holes, spray them with a multi-purpose fungicide and repeat the spraying with copper sulfate after a few days.
- In case of severe damage, remove the tree from the yard immediately to avoid spreading to other trees.
Spider mites are quite insidious creatures because they are very small creatures but can cause significant damage to Japanese maples.
These pests form colonies on leaves and leaf petioles and suck the juices out of them. As a result, the leaves slowly turn pale until they turn brown.
The first sign that the mites are present is a small white web between the leaf and the leaf petiole. You will need to use a magnifying glass to see them in more detail.
- If mites are present on one small branch wash them off with a stream of water.
- If the spread is large, spray the entire maple tree with a solution of acaricide. Repeat the spraying after a month.
- Burn or discard any dry or badly damaged leaves as far away from the yard as possible.