Apple tree diseases are generally of two kinds: it is often a fungal disease (powdery mildew, downy mildew, moniliosis, scab…) or a pest (aphids, flea beetles, codling moth…). If we can act curatively as soon as the first symptoms appear, the most efficient, but also and above all the healthiest for man and his environment, remains prevention.
This implies regular monitoring of pome fruit trees to anticipate the appearance of diseases. It also implies to gather a maximum of good conditions of culture so that the apple tree flourishes and is naturally more resistant.
Why are the leaves of my apple tree curled up?
Those curled up leaves on your apple tree can totally ruin your apple crop.
And if your apple tree is less than 4 or 5 years old, it may be living its last moments…
If the leaves of your apple tree are curling up, it’s not harmless.
It’s the sign of a pest that is taking hold: the aphid.
It can be :
- Ashy aphid
- The woolly aphid
- The green aphid
- The red gall aphid
Even though they function slightly differently, the consequences are (unfortunately) the same.
At first, they will be very few, and the damage will be little or not very noticeable.
But aphids reproduce at a tremendous rate.
For the woolly aphid, for example, there can be as many as 12 generations of aphids per year.
How do you deal with an apple tree that has its leaves curled up?
A small colony can quickly infest your entire apple tree and :
slowly but surely suck the sap from its leaves, buds, fruit and trunk
create deformations on the fruits
atrophy the branches
the leaves of the apple tree curl up, crinkle according to the aphid, and fall
Your crop can be totally destroyed because of the aphids that suck all the vitality out of the apple tree.
There are however auxiliaries that should limit them, as we hear a lot in permaculture. Ladybugs, for example, are known to feed on aphids.
But there is a double problem.
The first source is insecticides. Often, orchards are treated, more or less naturally (especially less). And it has been shown that insecticides limit the implementation of beneficials and their development.
The second issue, and not the least, comes from a species that protects aphids: the ants …. In fact, aphids are the ants’ cows. They breed them.
Why do we have to take care of the ants too?
Because the aphids’ excrement, the honeydew, is a nutrient-rich food for the ants.
It has been found that the damage caused by our friends (ladybugs, hoverflies, forficula) on aphid flocks is limited because of ants.
And … if the ordeal was not great enough … the honeydew causes a real descent into hell to our dear apple trees.
The honeydew, with its sticky texture, favors the attachment of the fumagina, a fungus that attacks our trees. This fungus will radically increase the vulnerability of the apple tree to many diseases and other fungi.
If nothing is done, the situation can become chaotic.
12 solutions to get rid of aphids on an apple tree
- Use of black soap: It prevents the aphid from breathing properly. Glycerin will block the pores and the aphids will die quickly
- Purins: of Tansy, Nettle, Rue
- Create an environment favorable to the auxiliaries:
- Parasitoid wasps (Parasitoid Hymenoptera),
- Parasitoid Hymenoptera,
- Aphelinus mali,
- As a preventive measure, after leaf fall: brush the shrub with white oil
- If it is a small colony: methylated spirits with a brush
- If it is a large colony : rubbing alcohol + dishwashing liquid + water on the shrub
- Glue tape: it will block a large part of the ants, and the auxiliaries will be able to destroy the aphids more easily. Very effective, and simple to implement if you have few trees to manage
- Use of pyrethrin : it is a derivative of chrysanthemum flowers which contains a substance that destroys the nervous system of insects
- Plant catnip, let the dock grow
- Avoid excess of nitrogen (as well as excess of everything): any excess will end up in the sap and the smell (or whatever) will attract pests like aphids more easily
- At the beginning of an attack: water the tree heavily
- Use a net
When to treat an apple tree against aphids?
Choose winter for your treatments. Winter is the ideal season to treat fruit trees. Since the trees are at rest, certain products can be applied without causing any harm to them and without creating too much damage to the auxiliary animals that are so precious to the gardener.
Why not use a pesticide?
So, in a panic, you might be tempted to apply a pesticide and that’s it! And this is true. The problem with this solution is that you will also limit the installation of beneficial insects, which could, over the years, potentially limit the negative impact of aphids.
As a result, every year you will have to apply pesticide … and …. here too, it’s not that simple. First, I guess you don’t want to harvest apples that are full of poison … and secondly, you should know that over time, aphids become more and more resistant to pesticides.