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Month: January 2021
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When do you prune cherry trees? Is there a difference when cutting young and old cherry trees? How to cut sour and sweet cherries? Find out everything you need to know about pruning cherry trees here.
Many gardeners aspire having their very own fruit tree orchard in the garden. And a cherry tree should definitely have a part in that. To ensure the tree producing as many cherries as possible, proper care is essential. Cherry trees require regular pruning. Pruning helps cherry trees to remain full of health. However, not every cherry tree has the same requirements: the larger but lighter sweet cherries (Prunus avium), for example, are usually much more vigorous than the smaller, usually dark red sour cherries (Prunus cerasus). Both trees require a different approach to pruning. In this article, we will tell you how to proceed when trimming cherry trees and what the differences are between pruning sweet and sour cherry trees.
When to prune cherry trees?
Cherries should be pruned annually. They do not respond well to rare and radical pruning.
When to prune sweet cherries?
While most other fruit trees are pruned in late winter, summer pruning is more suitable for sweet cherries. You can prune after the harvest, which is usually between the beginning of August and the end of September. Pruning cherry trees in summer curbs too much growth, which is typical for sweet cherries. In addition, cuts heal better in warm and dry weather, making the cherry tree less susceptible to diseases.
When to prune sour cherries?
Typically for fruit trees, sour cherries thrive best when pruned in winter. Ideally cherries are pruned between November and March.
Tip: Many gardeners are afraid that their cherry tree will lose vitality after pruning. The best way to prepare the tree for pruning is regular and proper care. Fertilise your cherry tree in spring using quality organic fertilisers. A healthy and well-groomed cherry tree can usually cope well with heavy pruning without any problems.
How to prune cherry trees?
The cutting of cherry trees is extremely important if you want to grow a vibrant and abundantly-fruiting tree. But how to trim a cherry tree? Before you start the process of pruning, you should consider the needs of your tree and the aim of pruning. The following questions should help you figure out the right pruning method:
How vigorous is your cherry tree?
On the one hand, strong growing varieties will grow even stronger when pruned regularly, but will produce less fruit. On the other hand, weaker growing varieties may need to be stimulated by pruning to produce new shoots which will bear fruit on. It is therefore important to consider the vigour when cutting the cherry tree. In summary: weak growing trees can be pruned more thoroughly than their strong growing counterparts.
How thoroughly should you prune and what effects does the strength of the cut have?
Radical pruning stimulates vegetative growth, i.e. the formation of new shoots and leaves. This can be useful if a tree hardly produces any new shoots and thus no new fruit wood. However, generative growth, i.e. the new formation of flowers and fruit, is also reduced by excessive pruning, and the tree then only reacts by forming more leaf mass.
How to prune cherry trees?
With cherries, branches are not cut just above the basis of the branch (the thickened part of the branch at its very beginning). It is important to leave a stump and not to remove all of the branch. It doesn’t matter if your goal is to just remove a branch from the middle shoots or to divert it to a side shoot. Always leave a stump of at least 7 cm in length. Cherry trees hardly ever truly heal their wounds; their wounds usually just dry up.
Which tool for pruning cherry trees?
From a certain size onwards, cherries are primarily cut with a branch saw or, even better, a fruit tree saw, and not with garden shears. The reason for this is that you usually remove whole branches and not just individual twigs. In any case, it is important to make sure that the tool is clean and sharp . If the blade is dull or rusty, the cut may fray. If, on the other hand, the blade is dirty, the wound can be contaminated – both can lead to poorer wound healing on the tree or even to infection of the cut and should therefore be avoided at all costs.
How to tell which cherry tree branches to remove?
Sour cherries in particular tend to form unwanted dominant side shoots time and again. To prevent this, proceed systematically according to the branch thickness ratio when pruning. First, the trunk and central shoot are viewed from top to bottom. If the trunk tapers at a point where a branch emerge, shorten it. The more the trunk tapers, the more the branch has to be shortened.
This also applies to the leading branches attached to the trunk. If the central branch becomes considerably narrower at one point, the outgoing side branch should be shortened accordingly. That way, you can promote shoots and branches to become leaders and create a beautiful canopy instead of a chaotic shrub.
What is the difference between pruning sweet and sour cherry trees?
Sweet and sour cherries, despite being closely related, differ significantly in their growth and are therefore pruned differently, which is why we will discuss the different methods in more detail below.
What is the aim of pruning cherry trees?
Pruning aims at various goals depending on phase of life. Formative pruning when trees are first planted differs from maintenance pruning and renewal pruning. Find the details below.
The basics of cherry tree pruning in summary:
- Adapt the cut to the vigour of your tree: strong growing trees are cut less than weak growing trees.
- The stronger the cut, the more the tree reacts with vegetative growth. This can impair fruit formation.
- Never remove the branch completely, leave a stump (at least 7 cm long).
- Cut the branches with a saw rather than with gardening shears or scissors. Remove whole branches instead of small twigs.
- Prevent the development of too many dominant branches: shorten branches where the main shoot tapers off considerably.
- Sweet and sour cherries are pruned differently (find explaination in the following).
Pruning old cherry trees
If an old cherry tree begins to age slowly, i.e. hardly grows at all, forms little new fruit wood and accordingly bears fruit sparsely, you can encourage it to grow again by pruning for renewal. Keep in mind, though, that the tree has to expend a lot of energy on new growth, hence generative growth (i.e. the formation of blossoms and fruits) is often less pronounced immediately afterwards. But don’t worry – as soon as the vegetative growth flattens out after being stimulated by pruning, the tree’s yields will significantly increase again. This is how you prune an old cherry tree:
- Reduce all dead or diseased branches of the old cherry tree to stumps.
- Shorten the leaders to a quarter of their size, and cut back overhanging branches
- Remove branches that grow into the inside of the canopy or cross each other
- Avoid tree wounds bigger than 10 cm.
- Prune and rejuvenate very old trees, over several years.
Renewal pruning is best done at the end of February. However, make sure to prune only in dry, mild weather, in order to prevent frost damage on the wood.
Important: Radical rejuvenation cuts can reinvigorate old cherry trees. However, this will most likely also shorten the life of the tree, as cherries do not cope well with invasive procedures in the long term.
Pruning young cherry trees
Many gardeners believe that young cherry trees do not require pruning. The opposite is true though. It is precisely in the young years that pruning helps establish the foundation for a beautiful and even canopy. Decide on the structure of the canopy before you start pruning. Sweet cherries are best grown with spindle or pyramid-shaped canopies. For sour cherries funnel-shaped canopies work best, as they are suited for the typical multi-branch growth. Once you have made your choice working towards your desired canopy architecture starts the first year after planting. Proceed as described:
- Determine the middle shoot, or several central shoots depending on the desired shape of the canopy.
- Select several branches evenly distributed around the leader(s) for side branches. Reduce excess branches to stumps. Ideally, the selected side branches grow at a 45° angle to the leader. Unfavourable growth of branches can be corrected by tying them up or down.
- Shorten the guide branches of the cherry tree by about a third, making sure that the length of the leaders is equal. When training towards spindle or pyramid shape, leave the middle shoot considerably longer.
- Remove any buds on top of the leaders.
Cutting a young cherry tree does not stop after the first cut. Especially trees younger than 5 years still have a sparse canopy. Encourage them to branch out by pruning the young tree at least 3 years in a row. Proceed as follows:
- Shorten the central shoot and the leading branches by a third. Make sure that all leaders are about the same length. Always cut on a leaf bud pointing outwards.
- Cut off branches on the leaders that grow inwards. Leave a stump of at least 7 cm long.
- Regularly shorten shoots on the leading branches that grow outwards to promote branching.
- For the following years remove fruit wood ,leaving about four buds on a branch, from which new fruit wood then develops.
- Tie oblique side shoots on leaders at a 45° angle. Reduce vertically attached shoots to stumps.
Pruning sour cherry trees
As with all cherry tree pruning keep in mind to prune according to the vigour of the tree, remove the branches with a saw and with regard to the thickness ratio (as described above). When pruning sour cherries, the overall aim is to avoid the canopy of becoming too dense and bushy and to reduce the leaders to a desirable number. The ideal canopy of a sour cherry is funnel-shaped. The best time to prune sour cherry trees is between November and March.
There are two main cultivars within the group of sour cherries – the Morello cherry and the Amarelle cherry. The Morello cherry type requires its own method of pruning:
- Morello cherry types only bear fruit on one-year-old shoots. That way the canopy quickly becomes full of bare, worn shoots that do not bear fruit the following year.
- It is therefore essential to cut off or at least shorten each shoot that grows cherries – this is the only way to ensure enough new fruit shoots forming for the coming year. As a rule of thumb, three quarters of the fruit shoots are cut back to at least a quarter of their length.
- Remove diseased, dead or very old wood and otherwise proceed according to the branch thickness ratio to support leader shoots.
In comparison, here is how to cut Amarelle cherry trees:
- On the whole, pruning this type of cherry trees tends to be less demanding, as they often develop a balanced canopy even without being pruned.
- The Amarelle cherry as opposed to the Morello cherry does fruit even on perennial wood.
- For this reason, the Amarelle cherries are cut similarly to sweet cherries.
Pruning sweet cherry trees
Pruning sweet cherries goes by the main principles mentioned above: pruning is carried out according to growth vigour, with a saw and with regard to the ratio of branch thickness. The aim of pruning is to maintain the dominance of the central shoot and to generate new fruit wood. Sweet cherries are cut after the summer harvest.
In contrast to Morello cherries, sweet cherry trees develop most of their fruit on short shoots, growing on annual and perennial fruiting shoots. For this reason, sweet cherry trees are cut more careully and less vigorously as to not remove any fruit-bearing wood:
- The first step in pruning sweet cherry trees is thinning out the canopy of the tree. Cut back branches growing inwards as well as strongly branched shoots with outdated fruit wood.
- Preserve younger branches with fruiting shoots; only remove them if they grow upwards very steep or cross or rub with other branches. By removing old and retaining new fruitwood, the younger fruitwood will produce higher quality and larger fruits than outdated fruitwood.
- In addition, when cutting sweet cherry trees, pay attention to rotten, diseased or dead branches – remove them as well.
- Compared to the sour cherry, sweet cherry trees have a stronger apical dominance, meaning that they grow more central on their own instead of producing many side branches. With regard to the branch thickness ratio, competing side shoots that point upwards should nevertheless be removed.
- In the case of sweet cherries, summer pruning is particularly recommended to limit their strong growth.
Info: Fruiting shoots are the short side shoots of cherry trees, arranged in a whirl-like manner. These often carry a particularly large number of flower buds and are therefore crucial for a rich harvest.
Pruning columnar cherry trees
If you don’t have enough space for a large and protruding cherry tree, you can opt for a columnar cherry. Thanks to its slender shape, this cherry’s growth habit is ideal for smaller gardens. They can even be cultivated in a large pot. However, to ensure that the tree does not lose its elegant shape, you have to prune them. Contrary to what some might believe, pruning columnar cherries is less complicated than the pruning of its larger relatives. Columnar cherry trees do not need to be pruned regularly, but only when necessary. The following steps are a guideline to cutting back a columnar cherry:
- Cut back side branches that are too long, shortening them down to 10 to 15 cm in length.
- Always prune far above a bud pointing outwards.
- Remove diseased, weak or steep growing branches.
- The middle shoot is not trimmed for the first few years but can be shortened afterwards if necessary.
Pruning dwarf cherry trees
Dwarf fruit trees, such as dwarf cherries, are a great choice for smaller gardens, as they require little space and can therefore be grown even in tiny gardens. As with all fruit trees, the dwarf cherry tree needs regular pruning to flourish. Since dwarf cherries can also be grown with spindle-shaped canopies, there is hardly any difference in the way dwarf cherry trees are pruned compared to large fruit trees:
- All side branches should only grow at a slight angle to the top and are not cut.
- Tied down steep branches to correct their direction of growth.
- Thin out the canopy where branches are too dense by removing one of them.
- Always cut off branches above a bud and leave a stump of at least 7 cm.
- Middle shoots are shortened to about 30 cm above the last side shoot.
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Plant protection products based on neem oil can be used for natural pest control of aphids, spider mites and other plant pests. You can find out how to use neem oil to protect your plants here.
Neem oil can be used in many ways. Its use as a plant protection agent shows great potential. In the following text, we give you exciting background information and explain how you can use neem oil in your garden or at home.
Neem tree: origin & characteristics
The neem tree (Azadirachta indica) belongs to the mahogany family (Meliaceae) and therein to the genus Azadirachta. This tree is also sometimes referred to as Indian lilac or nimtree. From this, you could deduce that the neem tree originated in South East Asia. More precisely, the neem tree commonly grows in India, Myanmar, Bangladesh and Pakistan. Because the neem oil extracted from the tree’s seeds is so popular and because it grows in most arid subtropical and tropical areas, the tree is now also cultivated in Australia, America and Africa.
The neem tree can reach a height of 20 metres and an astonishing age of up to 200 years. Additionally, it is very drought tolerant. It grows rapidly and can bear fruit after only a few years. A fully-grown tree can produce up to 50 kg of fruit.
The flowers are white, and their scent is reminiscent of jasmine. The resulting edible fruits are oval in shape and up to 2.5 cm long. The seeds they consist of up to 40% oil and that is where neem oil comes from. The helpful active ingredients of the neem tree are found in all parts of the plant, but in different compositions.
Almost all parts of the neem tree are used in different ways: leaves, seeds, flowers and even the bark. For example, during the Indian New Year, Hindu believers bathe in an extract made from the leaves of the neem tree. This supposedly cleanses not just the body but also the soul. Interestingly, the branches of the neem tree were formerly used to clean teeth.
Neem oil: production of the plant protection product
The fruits that fall from the neem trees are collected and the pulp is removed. What remains are the seeds, which are processed in a variety of ways. Neem oil is can be produced using these three methods:
- Cold pressing: The whole or ground seeds of the nimtree are gently pressed. This produces a yellow and bitter-smelling oil.
- Water extract: Another method to produce neem oil is water extraction. Unfortunately, it is not as effective, but it is cheaper than the other methods. The ground kernels are soaked in water and an extract is thus obtained.
- Oil extraction: Neem oil can also be extracted from the kernels. Saturated hydrocarbon (hexane) is used for this.
Many insecticidal and acaricidal substances are found in the neem tree. The former is effective against insects, the latter against arachnids such as mites.
- Azadirachtin (the main active substance)
With an optimal extraction of the oil from the seeds, an azadirachtin content of 30% can be obtained in the oil.
Tip: If you have purchased neem oil prepared in this way, you should store it in a cool and dark place so that it does not go bad and does not lose its effectiveness.
Neem for pest control
The active ingredients from the oil of the neem tree give us an excellent opportunity to control pests on plants in a natural way.
Neem oil can be used against these pests
Plant protection products containing neem are mainly used against insects that damage useful or ornamental plants with their biting or sucking. It is particularly effective against biting insects, as it is absorbed by the insects while they feed. The azadirachtin in neem oil has an inhibiting effect on feeding and disturbs the moulting (or ecdysis) of the insects. Neem has a wide spectrum of application and can be used against the following insects:
- Beetles (Coleoptera) like the potato beetle (Leptinotarsa decemlineata) or weevils (Curculionidae).
- Coleoptera (Homoptera), which includes aphids (Aphidoidea) or cicadas (Auchenorrhyncha).
- Diptera, or simply different species of flies.
- Butterflies and moths of the Lepidoptera order, which include pests such as the box tree moth (Cydalima perspectalis).
How to use neem oil against plant pests
Primarily, azadirachtin from neem oil is effective against the larval stages by reducing production of the hormone ecdysone, which is important for the moulting of the larvae. This disrupts or delays the larval metamorphosis and prevents adult insects from developing from the larvae. The insects either die, are damaged or can no longer reproduce. In adult insects, neem inhibits the feeding activity. Death is not immediate, but the feeding stop occurs relatively quickly. As these hormones are very widespread in the insect kingdom, azadirachtin and neem are not specific, but have a broad effect. It should also be noted that azadirachtin only affects the last larval stages and some degree of damage by larvae cannot be avoided completely.
The following effects of neem oil can be observed in insects:
- Feeding inhibitor
- Feeding deterrent
- Moulting and pupation disorders
- Disturbance during egg laying
- Reduced reproductive capacity
As the active ingredients of neem oil are absorbed by the plants, insects that do not come into direct contact with the agent but eat the plant or mine through leaves or roots can also be detected. Mining means that an insect eats inside a leaf and thus creates tunnels or mines. The absorption of the active ingredient into the plant is sub-systemic, so it is not distributed throughout the plant, but only in the immediate vicinity of the sprayed parts of the plant.
Tip: Preparations based on neem oil are particularly effective against aphids or whiteflies.
Neem oil pest control & plant protection
Important: The use of specially mixed preparations of neem oil as plant protection agents is not permitted. In the EU, only products that have been tested and approved are allowed for use. Illegal use could result in substantial fines. The same applies to the use of vinegar, rapeseed oil or soft soap on plants. If you want to use the oil of the neem tree, we recommend an approved product based on neem oil.
Neem can also be used as a powder, which is just as easy to buy as neem oil. Residues from oil production – the neem cake – can be dried and processed into powder or pellets. These products can be worked into the soil to improve it. Moreover, neem cake can be used as a fertiliser and can even combat nematodes that dwell underground and damage plants.
The by-product of neem oil production, the neem cake, can be used in other ways, too. The neem cake consists of the whole seeds of the neem tree, which are crushed.
This precious oil has many advantages, but like any remedy, neem oil has side effects. Some plants are sensitive to the product and lose their leaves through phytotoxic reactions. All in all, processed and diluted neem preparations are better tolerated by plants than pure neem oil.
Although it is amazing just how versatile neem is in plant protection, neem oil cannot distinguish between pests and useful species and, unfortunately, can just as easily harm beneficial insects. Beneficial insects, such as parasitoid wasps Aphidius rhopalosiphi, lacewings (Chrysoperla carnea) or predatory mites (Amblyseius cucumeris) can react sensitively to neem oil. It is therefore extremely important that neem preparations are only used in accordance with the recommendations for use on the packaging or the instruction manual. This will keep the risk as low as possible.
Using neem oil in other ways
The ingredients of neem oil can also be used for our pets. Neem oil can be used to treat wounds or to ward off insects. Neem is not only good for our plants and animals however, we can also use neem ourselves.
Important: Some scientific studies have shown that neem oil treatment can lead to some degree of discomfort and in worst cases, even symptoms like tremors in some cats. For this reason, we advise to consult your vet before using neem oil on your cats or in close vicinity to your cats.