Apple trees are one of the easiest fruit trees to grow in a UK garden. Some form of protective cover such as fruit cages, however, can make it even easier to get a bountiful harvest from an apple tree wherever you live in the UK.
A fruit grower can encounter a range of apple tree problems – they can be prone to certain pests and diseases. Fortunately, however, it is possible for an organic gardener to reduce the incidence of these problems and in this apple tree guide, you can learn how to identify problems and take care of your apple trees organically all year round.
Protecting An Apple Tree From Pests
There are a number of common pests that can pose a problem when growing apples in your garden. These can include a number of aphid and moth species, capsid bugs and apple sawfly. Recognising which of these pests may be posing a problem for you apple tree is an important part of apple tree care. However, there are also general measures organic gardeners can take to protect their apple trees from a range of different pest species.
One of the most important protective measures that you can take to protect fruit trees is companion planting. Creating a guild of beneficial companion plants around each of your trees will help to keep the ecosystem in balance and thereby reduce pest problems in your garden. Guilds of shrubs, herbaceous plants, ground covers and other layered components are selected to benefit the fruit trees you have chosen in a range of different ways.
An apple tree guild should include:
- Dynamic accumulators (nitrogen fixers, such as legumes and shrubs like elaeagnus, and deep-rooted perennials such as yarrow, dandelion, borage and comfrey which can be chopped and dropped to add mulch around the tree).
- Plants to create ground cover to protect the soil ecosystem around your apple tree. (Avoid grass or other weeds which will compete with your apple tree for nutrients and plump instead for beneficial companion plants.)
- Alliums such as onions, garlic and shallots. (Their strong smell will help to repel certain pests.)
- Other bulbs. Alliums and other bulbs such as spring daffodils help to repress grass around an apple tree, thereby reducing competition and allowing an apple tree to grow strong.
- Aromatic herbs to attract predatory insects which will help to keep aphids and other pests species in check. Dill, fennel and coriander are three examples of aromatic herbs which can fulfil this purpose.
- Aromatic herbs and flowers to repel pests, such as nasturtiums, tansy as well as alliums and a wide range of aromatic herbs.
While a healthy guild can help to keep pests in check by helping to create a thriving, biodiverse ecosystem around your apple tree, the only sure fire way to prevent pests from harming your fruit trees is to protect them under some sort of cover.
While apple trees can be successfully grown without any form of netting or caging, it could be worthwhile considering a fruit cage or netting if you are dealing with a pest problem where you live.
Keep Your Tree Healthy:
Pests do not usually pose too much of a problem for apple trees in a UK garden. As long as your tree enjoys a relatively high base level of health, it should be able to deal with moderate pest populations and still provide a decent yield.
There are a number of problems that can arise when your apple tree is not in good condition, so if you encounter a problem, the first step is usually to discover whether there are any situational problems caused by the environment in which your apple tree is grown. Environmental problems could include:
- Overwatering or under watering.
- Poor nutrient content in the soil, a problematic soil pH, or waterlogging caused by heavy clay soil.
- Too much or too little sunlight.
- Root disruption caused by strong winds./ exposure.
Before you seek to delve deeper into the problems experienced by an apple tree in your care, organic gardeners should always begin by making sure that they are satisfied that all the trees basic needs have been adequately met, and that it is in a location that allows for optimal growing conditions.
Ensuring good biodiversity around your apple tree, and maintaining good organic gardening practices will usually be sufficient to ensure that your apple tree remains in good health and provides a plentiful harvest. But there are sometimes specific apple tree diseases which can pose a problem for an apple orchard.
Read on to learn more about identifying the most common apple tree diseases and what do do about these problems in an organic garden.
Identifying Common Apple Tree Diseases
Below you will find brief descriptions of some of the most common apple tree diseases:
Apple canker is a fungal disease which is identified by depressed patches of dead bark. Infections are often first seen at the sites of wounds or buds. Die back can spread, affecting larger limbs and fruiting spurs. Developing fruits are also sometimes attacked and these can rot and fall off the tree.
Apple canker can be worse on wet, heavy, acid soils. Raising soil pH can sometimes help to reduce the incidence of this apple tree fungus. The main way to reduce recurrence of this issue is to cut out all affected material as soon as possible. (More information on pruning apple trees can be found later in this guide.)
Apple scab is another airborne fungal disease. It is caused by Venturia inaequalis, which survives through the winter on fallen leaves. Apple scab causes dark splotches on the leaves and fruits, sometimes causing them to fall early, and can crack and blister young shoots allowing apple canker to enter.
As with other fungal diseases, the main method of control is to prune out affected material as soon as possible, and to clear away any fallen leaves that are affected as soon as possible. This can help to reduce the fungal spores that remain to cause problems the following season.
Brown Rot & Blossom Wilt:
Another fungal disease, those one causes blossom wilt in flowers and fruiting spurs, and will cause a brown, spreading rot in the fruits. Severity of the symptoms can vary year on year and an attack can be concurrent with other diseases.
Again, removing all affected material as soon as possible can help to control an outbreak and prevent it from recurring more severely in following years. Brown rot infects an apple tree through wounds, especially those caused by birds, so netting or growing apple trees in a fruit cage can help by reducing bird damage.
Honey Fungus (Apple Tree Fungus):
Honey fungus is one of the most common root diseases on apple trees. Roots that are affected will decay and a white fungus will often be seen between the bark and wood at ground level. This is caused by a number of different fungi and is one of the most destructive fungal diseases in the UK, killing apple trees and other perennial plants.
Unfortunately, the only way to eradicate this disease is to remove the tree that is affected entirely, including the roots. Resistant or less susceptible plants should then be grown in the area.
Often affecting trees already weakened by other diseases or problems, coral spot is another fungal disease, this one identified by small, coral pink raised spots which form on dead or dying branches.
Be sure to cut out any affected branches as soon as possible to prevent spread, and reduce the risk by pruning correctly during the right periods, as described below.
Fireblight is a bacterial disease that can kill the shoots of apple trees and make them look as though they have been scorched by fire.
Affected material should be promptly pruned back to healthy material and burned to prevent the infection from spreading throughout the garden.
Silver Leaf Disease:
This fungal disease is characterised by the silvering of leaves and by branch die-back. It infects a tree through wounds, often those caused by improper pruning. Silvering can also be caused by other environmental problems or stresses on an apple tree, but true silverleaf can be identified by the presence of an irregular, dark staining inside branches.
Following correct pruning procedure can help to reduce the likelihood of an outbreak. Affected branches should be removed and disposed of as soon as possible to prevent spread.
There are, of course, a wide range of other diseases found on apple trees, but the above are amongst the most common. In other cases, the solution is usually the same: keep trees healthy, improve biodiversity and prune to remove affected material. A guide to pruning apple trees can be found below:
Pruning Apple Trees
When pruning apple trees, always keep in mind the reasons for pruning, and what you are tying to achieve. Gardeners should prune to:
- Take out some old growth to stimulate new. (The majority of fruiting wood should be 1-4 years old for optimal yield.)
- To thin the canopy to allow light to enter the heart of the tree. (This improves air flow which reduces the incidence of disease, and allows fruits to fully ripen more easily.)
- To create a pleasing shape for your tree and to keep its size in check.
- To remove dead or diseased material to keep your tree healthy.
When to Prune an Apple Tree:
Apple trees should usually be pruned in the winter months, during the dormant period. Aim to prune during dry weather between November and the beginning of March. The only exception to this is pruning for shaping and thinning of restricted apple tree forms such as those grown as espalier, fan or cordon forms.
How To Prune an Apple Tree:
- Aim to remove around 10-20% of the canopy in each winter pruning session. Do not over-prune as this can encourage water shoots which grow straight upwards in vigorous growth.
- Do not be tempted to cut through very large limbs unless absolutely necessary. Larger wounds can often be more likely to allow disease to enter your tree.
- Cut branches at different levels, paying attention to reducing crowding and creating a pleasing and productive shape for your tree, rather than just giving your tree a ‘hair cut’.
Make sure that you use sharp tools and cut branches off neatly. Take care and work safely. Pruning is an art, not a science. Err on the side of caution and remember that it is usually best to take too little rather than too much.
Let us know how your apple trees are doing and share any tips or suggestions in the comments below.
Elizabeth Waddington is a writer and green living consultant living in Scotland. Permaculture and sustainability are at the heart of everything she does, from designing gardens and farms around the world, to inspiring and facilitating positive change for small companies and individuals.
She also works on her own property, where she grows fruit and vegetables, keeps chickens and is working on the eco-renovation of an old stone barn.