When the garden is at rest, we finally have time to give our fruit trees a few extra care sessions. Tree care in winter includes, among other things, measures against plant pests and protecting the bark to prevent the penetration of pathogens through frost cracks.
Pruning fruit trees: Finding overwintering pests
A magnifying glass helps to track them down. Look for the eggs of the fruit tree spider mite (orange) and the apple aphid (black), especially in bark cracks, on branches and on the ringed fruit wood. If you find them, you can carefully brush off the round to oval eggs with a wire brush, but without damaging the tree. If there are too many eggs, plan a sprouting spray for March.
Remove persistent pests with brushes
Use a tree scraper or bark scraper, a wire brush or a paint or varnish scraper to remove loose bark scales from trunks and thick branches of older pome fruit trees. This also removes lichens, mosses and pests that persist under the bark, such as codling moth. Place an old sheet under the tree beforehand. Caution: Do not brush the trunk and branches of young trees!
Glue rings against frost moth
The glue paper or glue coating to trap the frost moth remains on the tree trunk until budbreak. Replace it when it is no longer sticky.
Lime protects the bark
A coat of white lime protects against deer browsing and frost cracking. Apply the coating in frost-free weather with a broad brush to the trunk and, in the case of young trees, also to the branches. Renew the coating regularly, as precipitation gradually washes it off. Another advantage of the white whitewash: the trees sprout later in spring and late frost damage to the blossom can be avoided. If no whitewash is available, brushwood or reed mats can also protect the trunks of young trees from frost damage.
Prune fruit trees: What else is noticeable on the trunk
They look worrying at first, but are normal where thick branches have been removed. Here, the tree has detached itself and no longer supplies the tissue. This rots, and bats and cavity-nesting birds such as tits and woodpeckers nest in the resulting holes. But: Keep an eye on such a tree, because tree-decomposing fungi can also move in and endanger the tree.
On old trees, you will often see the consoles of shaggy shill fungus, sulphur fungus and plum fire fungus. When they appear, they have already covered the tree with their mycelium and are slowly decomposing the wood. Prevent wounds and frost cracks and remove the fruiting bodies to avoid spreading to other trees. Fruit tree canker As a rule, trees can close larger wounds well themselves. However, if the fruit tree canker penetrates, the fungus keeps the wounds open. Typical are the thick bulges around the former injury. As a preventive measure, treat wounds caused by branch breaks or pruning measures and lime against frost cracks. Cut back infested areas into the healthy wood.
Green knowledge: Why a coat of lime protects against frost cracking
Frosty, clear winter days can be dangerous for the tree, because strong temperature fluctuations affect the bark: while the side of the trees facing the sun is warmed during the day, the opposite side is still in the shade and frozen. As a result, the tensions in the wood can lead to bark cracks that weaken the tree. The bark can also crack due to excessive sunlight. Bacteria, fungi and pests enter the tree through the resulting wounds. Young trees and trees with smooth bark such as plum, cherry, peach and walnut are particularly at risk. Older apple and pear trees, on the other hand, have thick, temperature-balancing bark. A white coat of lime on the trunk reflects the sunlight. It prevents the wood from heating up too much and thus reduces the temperature differences in the wood.
Pruning fruit trees in winter
Most fruit trees tolerate pruning very well on cold days. Only from minus ten degrees can the wood become so brittle that it breaks or tears when cut. That would be bad for healing. Otherwise, you can use the winter time to prune apples, pears, plums, sweet or sour cherries.In late frost areas, however, it makes sense to postpone fruitwood pruning of grapevine, apricot, peach and nectarine until spring, when it is clear which shoots have suffered frost damage.Jostaberry, currant, gooseberry and raspberry should receive their final pruning in January at the latest. In the case of the more frost-sensitive blackberries, it is better to leave a few more fruit shoots than necessary – as a reserve for winter losses.
Many an apple tree has grown well and is far from being over-aged, but the variety does not meet your needs? Why not make a multi-variety tree out of it or graft it with another variety. Then now is the time to take care of the scions you will need for grafting in spring. Suitable are all shoots from trees of the same fruit species that have grown during the previous season, are of medium vigour and show no signs of disease.
The exceptions to cutting fruit trees
Peach and apricot are better budded in August with fresh summer shoots. Walnuts and grapevines are best left to the experts. The scions must not wake up from bud dormancy until grafting and should therefore be stored frost-free but as cool as possible. This is especially important for stone fruit. Once the scions of your desired varieties have been gathered, they should be stored in a cool, shady place. Professionals keep them at about two degrees Celsius in cold storage rooms, but in the garden a shady spot facing north will do. If you do not want to obtain scions yourself or do not have a suitable donor tree at hand, you can get them from a rice nursery at grafting time.
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I have worked as a horticulture specialist lead gardener, garden landscaper, and of course i am a hobby gardener at home in my own garden.
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