Apple tree pests and diseases UK

Identifying Apple Tree Pests and Diseases in the UK

All plants, including fruit trees, have to battle pests and diseases. Some are common enemies among the plants and some are unique to specific plant species. Apple trees suffer from both common pests and diseases as well as some that seem to enjoy the apple tree better than any other type of fruit tree.

While the apple tree must battle against pests and diseases almost constantly, there are a few things that we can do to help them win the war and live a long and productive life. Start by planting the right apple tree variety and then learn how to become a good fruit tree inspector.

Start With the Right Apple Trees

Select an apple tree variety that is suited to your climate. Find out which growing zone (hardiness zone) that you live in and select fruit trees that are hardy in your zone.

Also take into consideration the elevation, amount of rainfall, air circulation, and soil conditions of the area where the apple trees will be planted. If the right tree is planted in the right place it can put its’ energy into developing fruit and fending off pests and disease instead of just struggling to stay alive in a hostile environment.

A weakened apple tree is far more likely to fall prey to pests and diseases than a strong, healthy tree.

identifying apple tree problems

Right Location

Apple trees need plenty of direct sunlight, air circulation, and well-draining soil. They also need pollinators. Know the flowering time of the apple trees that you want and when the native pollinators are in your area to ensure the apple blossoms will be pollinated.

Most apple tree varieties are diecious and require at least one other apple tree to be nearby plus pollinators to produce apples. There are a few varieties that are self-pollinating and can be grown as a lone fruit tree, but it will still need to be planted in the right location to have its’ other needs met.

Apple Tree Pests

These are a few of the common pests and the tell-tale signs they leave behind. Inspect apple trees frequently and begin treatment as soon as any of these signs are noticed.

  1. Aphids are tiny insects that hide on the underside of leaves. They huddle in clumps and suck the sap from new leaf growth and tender stems. Tree leaves will become curled and distorted when aphids are present. The tiny insects also leave behind a sticky substance that will attract ants and turn black with mold.
  2. Red mites are identified by clusters of tiny red eggs laid on the tree bark. The eggs will hatch in the spring and 1,000‘s of red mites will burrow under the bark of the apple tree and will place it under stress, causing the apples to be small and distorted. The red mite eggs can be killed with horticulture oil or insecticidal soap.
  3. Winter moth shows up in early spring with tiny green caterpillars hanging from the tree by a thin thread. They will grow into large caterpillars and eat all the tree foliage. Spray apple tree with horticulture oil in early spring before the tiny caterpillars show up so the eggs will be suffocated. After caterpillars show up, spray tree with an insecticide.
  4. Woolly aphids congregate to create white fluffy patches on tree branches or trunk. Just like the tiny green aphids, woolly aphids are sap suckers and have created a wound in the tree so the sap will be easier to get too. The sticky substance they leave behind attracts ants and the wound they create can cause the apple tree to become susceptible to canker. Spot treat woolly aphids with neem oil.

Apple Tree Diseases

blossom wilt on apple tree
Blossom wilt (source: ADHB)

Blossom wilt is a fungal disease that causes the apple blossoms to shrivel up and turn brown. The leaves near the blossom will also shrivel up and turn brown. If the tree manages to produce any apples, they will also shrivel and turn brown before reaching maturity. Pruning off the affected branches is the only treatment. The pruned branches, along with all fallen leaves under the apple tree, should be burned to prevent the fungus from spreading.

Canker Apple Disease
Apple Canker (source: RHS)

Canker is a fungal infection that enters the tree bark anywhere there is an opening. The tree bark will begin to sink in and crack open. Pruning off the infected branch is the best treatment method.

Galls on apple Apple tree
Galls (Source: Geograph)

Galls, sometimes called burls, are unusual lumps on the tree trunk or branch. They are caused when the apple tree has been wounded and bacteria has entered the wound. There is no treatment for galls and typically the apple tree thrives without any health issues caused by the gall. In some cases, however, the bacteria inside the gall will kill the tree. Only time will tell which way it will go when a gall has been discovered.

Powdery Mildew Apple tree disease
Powdery Mildew (source: Flickr)

Powdery mildew looks like a fine layer of baby powder has been sprinkled over some of the apple tree leaves. Powdery mildew usually attacks in early spring when tree leaves begin to emerge and it can spread to fruit and branches. This is a fungus and should be treated early with a fungicide to prevent it from spreading.

Scab (Source: Wikimedia)

Scab is a fungal disease that leaves yellow and green spots on the tree leaves and the apples. Remove all affected leaves and fruit, then treat the apple tree with a fungicide to kill the scab.

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