Common leaf diseases on fruit trees

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fire blight

Fruit trees can be attacked by various diseases. Fortunately, leaf diseases are not that common, but the leaves are good for many diseases. The most dangerous fruit tree diseases are fire blight and sharka, followed by the fruit tree crayfish.
fire blight
Many leaf diseases are caused by fungi, while the fire blast is a bacterium (Erwinia amylovora). It is not a pure leaf disease, but best seen on the leaves. Affected fruit trees are mainly Kernobstarten, so apple, pear, quince and others. There are several possibilities of infection and spread, such as migratory birds, the weather, contaminated plant material, insects, animals and even by humans. The most common type of infection is the flower infection, followed by the instinctual infection and re-active older infestation sites. It can be recognized by the fact that the leaves of some shoots are black-brown discolored and dried up. The bacterium clogs the pathways. The leaves can no longer be supplied with water, they die.
  • bacterium
  • No pure leaf disease, but recognizable by the leaves
  • Infection from spring to autumn possible
  • Ideal growth temperatures between 21 and 28° C
  • Particularly endangered are the flowers
  • Entry ports flower stem, breath openings, wounds
  • Spread depending on tree health and age
  • Bacteria survive in the diseased bark (sunken bark plates)
The fire blight is notifiable. It is a quarantine disease. Suspicious symptoms should be reported to the Plant Protection Office. If it is proven to be fire blight, control measures are prescribed. Not only pome fruit trees are attacked, but also other popular woody plants, such as mountain ash, rock pear, ornamental apple, medlar, glossy medlar, hawthorn, hawthorn, hawthorn and others. Fire-fighting is only to fight against older trees. Young fruit trees should be cleared. In heavy infestations, the clearing is also the best option. Important in the choice of variety is to select a robust variety of fruit. Resistances do not exist.
  • Cut the sick shoots back to healthy wood
  • Report infestation (Plant Protection Office)
  • Accumulated wood must not be composted
  • It is best to burn
  • Disinfect cutting tools (with 70% alcohol)
  • Plant robust fruits
Sharka disease is caused by a virus that affects stone fruit, mainly plums, plums, peaches, nectarines and apricots. This disease is also notifiable. Due to different virus strains, the symptoms of the plants may differ, or they are different pronounced. You can see bright olive green rings, which can develop into black dots (dead tissue) on the leaves. These form mainly in the spring, from about May / June. In contrast, the fruits have depressions which are small-pox-like or linear. Underneath, the pulp assumes a reddish color and it gets a rubbery consistency. Often, the fruits fall prematurely.
  • viral disease
  • Afflicts stone fruit
  • Prefers some fruits
  • Recognizable on light olive-colored rings on the leaves, mainly in spring
  • Later black spots (dead tissue)
  • Fruits also affected
  • Particularly intense occurrence of heat and drought during the growing season
  • Transmitted by aphids or by treatment with infected rice or rootstocks
You can not fight the virus directly. However, the spread should be avoided or at least reduced. This can be done through a few targeted measures. Also prevent is not possible.
  • Fight aphids
  • Clean and eliminate infected plants
  • Use virus-free scions and documents
  • Plant less susceptible or resistant varieties and substrates
Apple scab
Apple scab is one of the most important apple tree diseases worldwide. The causative agent is the ascomycete, Venturia inaequalis. Typical are dull olive-green spots on the leaves, which can later turn brownish to blackish in color and flow together. They form necroses, which in turn leads to premature leaf debris. The disease can also be recognized by the fruits. They usually have darker colored spots. In these star-shaped cracks can occur. Through the cracks other pathogens get into the previously damaged apple again. This affects the shelf life, but has no effect on the consumption.
  • fungal disease
  • Affects leaves and fruits
  • In addition to apple also pear, cherry, peach and other fruits affected by rust
  • High propagation rate
  • Infection is weather dependent, wet and temperatures between 16 and 22° C are ideal
Prevention is better than cure. Important is already the selection of robust fruit tree varieties, as well as the right location and good care. Meanwhile, resistant varieties are already on the market, they should be preferred. Furthermore, the following things should be noted:
  • Dispose of fallen leaves and fruits. Do not leave it behind and do not give up on the compost
  • Cover the trees regularly so that the leaves can dry well (wind)
  • Balanced fertilization
  • Preventive spraying with appropriate means (always only before precipitation)
  • First injection before the spore flight in March
The combat includes spraying at the beginning or just before the sporula flight in late March. Favorable is a combination of preventive pad and contact spraying. For the home garden are not allowed the same means as for the cultivation of crops. In addition, which are constantly taken from the offer or come to new. Here you should get the appropriate information from a specialist.
  • Spraying for prevention
  • Surface spraying - all infected tree parts are protected by a closed surface
  • It is important to comply with the concentration and the recommended application.
  • Usually at least 5 sprays are necessary, at intervals of 7 to 14 days
apple mildew
The powdery mildew is a powdery mildew and is caused by the fungus Podospharea leucotricha. Leaves, but also other parts of plants are covered with a whitish-floury layer, which also explains the name apple powdery mildew. The pathogen lives on the surface of infested plants, but penetrates into these for water and nutrient removal. Infections are only possible on young tissue.
  • fungal infection
  • Only apple trees, fungus has specialized
  • Whitish-floury surface on affected parts
  • Only young tissue is infected.
In addition to leaves, flowers, shoots and fruits can also be infected
  • Infested flowers do not produce fruit
  • Usually occurs between mid-May to mid-June.
  • Prefers dry weather and temperatures between 20 and 25° C
  • Affected leaves dry up and fall off. Jahrestriebe verkahlen from below. Apples show a net-like russet.
Here, too, all kinds of prevention can be achieved. Infected shoots should be removed in time, right at the winter cut. It is also important here, a light crown, which is why regularly should be lighted. In addition, susceptibility depends on the species. Some varieties are highly susceptible, such as Jonagold, Elstar and Cox-Orange. As a rule, apple varieties with hairy leaves are more susceptible than those with bare leaves.
  • Make regular
  • Remove infected shoots
  • Select apple varieties with smooth leaves
  • No varieties with hairy leaves
The infestation can be prevented or contained by a combination of different measures. These include the cutting measures and spraying.
  • Winter cut - remove infected shoots
  • Regular breaking out of infected shoot tips in early summer
  • Spraying with sulfur in susceptible varieties
  • After flowering, start into August
Pear rust
Pear lattice is a fungal disease, more specifically a rust fungus. Actually, this fungus infects a variety of juniper species. There he causes nodular thickening of the branches. In the spring, the spores are distributed by the wind and thus reach the leaves of the pear trees. This infection thus begins at the top of the leaf. At first orange-red spots are visible on the leaves. These increase continuously. If the weather is right, the fungus can multiply explosively. Insects help. They are lured by excreted nectar. In summer, the fungus grows through the leaf. Now on the underside of the leaves irregular, brownish growths, spore storage arise. If the spores are ripe, the surface bursts, the winter spores fly out and can now infect the juniper again.
  • Young trees can be seriously damaged
Growth and harvest are severely impaired
  • Settles on juniper
  • Especially two junipers are affected: Sweet tree (Juniperus sabina), Chinese juniper (Juniperus chinensis)
  • fungal disease
  • Spores infect pear trees
  • Orange-red patches on leaf top
  • Later irregular, brownish growths (spore storage) on the underside
  • At Sporenreife the spores fly off
To prevent the infestation you can only remove all juniper from the garden. But if the neighbors have some, you have to convince them too. Safer is then the use of plant tonics such as horsetail extract. The trees should be sprayed every 14 days, at least 4x after the shoot.
  • Remove juniper
  • Resistant species plant e.g. Juniperus communis, common juniper.
The fight must start with the pear tree and juniper, otherwise the cycle will not end. At juniper the winterspore camps have to be fought. The best is the removal of the affected trees and shrubs. The flying radius of the spurs is about 500 meters, in strong winds more.At this distance, the trees should be removed. Usually this limit goes beyond your own garden and the distance becomes difficult. The owners often do not see that. Sometimes, however, the removal of affected areas on the trees is sufficient. Alternatively, the planting of resistant species offers.
  • Juniper control: Cut out affected areas or even better, remove entire plant, alternatively plant a resistant variety
  • Control of the pear tree: spraying fungicides, preferably in the spore flight phase (Duaxo Universal fungus-free from Compo) The agent also acts against other fungi, e.g. Rippling disease, rust, scab, powdery mildew and many types of leaf spot diseases. Use plant tonic, inject prophylactic triazole every 14 days
sooty mold
Russtau is a black fungus. He occurs mainly in late summer. The soot mushrooms settle with preference leaves on which honeydew sticks. This in turn are the excretions of leaf and scale insects, white flies and cicadas. Affected are apple trees, pear trees, apricots, cherry trees, peach trees, plums and plums. To detect the infestation of black-coated different sized spots on the top of the sheet. The leaves can also be dyed completely black. They can no longer absorb solar energy and die. For fruit trees, the damage is usually not very strong. Ants harvest the sticky secretions.
  • Fungal Disease - soot fungus
  • Settles on excretions of harmful insects
  • Many fruit trees affected
  • Usually no strong damage
You can not prevent much. Strengthening the trees is a good option. Plant tonics help. In addition, the trees must be regularly checked for pests in order to combat them as soon as possible. If there is no honeydew, there is no soot fungus.
  • Plant strengtheners
  • Check pest infestation
The fight is mainly directed against the pests. Especially aphids must be combated. In addition, ants are kept away from the trees. They promote honeydew secretion as they want to harvest. They keep the aphids more or less like pets.
  • Pest control, especially aphids
  • Keep ants away
Shotgun disease
From the shotgun disease apricots, cherry trees, peach trees, plums and plums can be affected. The causative agent is a fungus, more specifically Wilsonomyces carpophilus. The disease can be recognized on the new leaves. There are reddish brown, round spots, which later become holes. In case of heavy infestation the leaves look like shotgun bullets, hence the name of the disease. The affected leaves dry up and fall prematurely, usually in June or July. Often lower tree parts are more affected than upper ones. Early on, the trees can be completely bare. The fungus can also attack branches. Young shoots show cracks. Even fruits are affected. They show red-rimmed spots and funnel-shaped indentations. Every now and then they are completely crippled. Whole branches can die off. The trees are particularly endangered from May and then until the end of the growing season.
  • fungal disease
  • Occurs mainly in damp coolers, precipitation-rich weather
  • Mushrooms explosively under favorable conditions
  • Particularly at risk are areas with heavy fog
  • Spread by raindrops
  • Mushroom penetrates into the epidermis and into the tissue
  • Can also penetrate via the attachment points of fallen leaves
In order to combat the shotgun disease, infested leaves must be removed. This also affects infested fruits. Heavily affected trees should be cut back to the healthy wood (wood can also be infected). This lowers the infestation pressure and the leaves in light trees dry faster. For peach trees should be injected immediately before the leaf fall with copper preparations. This prevents late infections. Alternatively, it can be sprayed with synthetic fungicides in summer.
  • Remove leaves and infested fruits
  • Cut back hard
  • In case of peaches inject to prevent a late infection.
  • Restrain sparingly, especially nitrogen
  • Organic farmers use clay preparations and net sulfur
leaf curl
The Kräuselkrankheit is also called bladder disease. It is triggered by a fungus and affects mainly peach, nectarine, apricot and almond trees. The disease can be recognized on the leaves, which curl markedly and show light green and / or red blisters on budding in spring. The diseased leaves turn to whitish green and appear rubbery and brittle in the final stage. The tree drops the leaves, but produces a healthy renewal. The good thing is that the fungus is not infectious at over 16° C. However, the tree is weakened overall and the disease occurs several years in a row, whole branches can die off and at the end of the tree must be cleared.
  • Pathogen is a tubular fungus
  • From the end of February / beginning of March, shoot cells are rinsed by rain into the buds of the tree that are just opened. There, the unfolded leaves are infected and flower buds proliferated. From this point on, there are no antidotes.
  • At May the mushroom forms spore camp. To recognize as a tender, plushy fluff.
  • Infest occurs especially in damp winters
Prevention is best done by planting disease-resistant varieties, if any. It also helps enormously to plant the trees on a house wall or even better under a roof ledge, to protect them from rain during the critical winter months. This is the only way to prevent the infection. If necessary, a tarpaulin can also be suspended, at least until the temperatures rise above 16° C.
  • Plant disease-resistant varieties
  • Plant trees near the house or under a roof ledge
  • If necessary, protect with a tarpaulin
  • Glue rings on the trunk
  • Sufficient irrigation
  • Sufficient nitrogen fertilization
  • Plant strengtheners
The fight is difficult. In the cultivation of crops there are sprays, but these are not permitted for the home garden. Since new funds are approved every year, it is worthwhile to inquire about it in the specialist trade.
  • Sprinkle with fungicides shortly before bud break-up in January or February, mostly copper-containing compounds or peracetic acid
  • Start at temperatures above 10° C
The tan is a fungal disease that affects the leaves and young shoots. Mainly affected are sweet cherry trees and quinces, but also apricots, and sometimes apples and pears. The leaves of the cherry trees turn brown at the end of May, but do not fall off. By the end of August, the entire crown will turn brown. The leaves remain hanging in winter, but they remain rolled up. Clearly visible are the twisted petioles. In the quince, chlorotic, pale yellow discoloration of the leaves can be seen. It can come to the falling of the leaves. The fruits are also affected and not suitable for consumption.
  • When cherries - leaves turn brown, roll in and stay hanging, even throughout the winter
  • In quince - pale yellow discoloration of the leaves, often based on calcification of the soil
Plant tonic substances such as horsetail broth serve as prevention. With budding beginning should be injected repeatedly. In case of infestation in the months of May to June should be sprayed twice with copper agent, which, however, is not approved for home gardens.
  • Plant tonic such as horsetail broth
  • Inject copper agent
  • Give fruit trees a lot of space, they should stand free
  • Distance to buildings or other trees 6 to 12 m
  • Annually crown the crown
To combat the tan, all leaves should be collected and destroyed. They do not belong to the compost. If copper compounds are allowed, then spray before budding. Always keep the crown light and cut regularly.
There are a lot of leaf diseases in fruit trees. Not all are pure leaf diseases, it can also fruits, flowers and shoots are affected. In some diseases, however, the leaves indicate the infestation, you can identify them well. There are bad diseases that can end with the death of the tree and also rather harmless ones. In any case, prevention is better than cure. Important is the selection of robust fruits. Also location and care must be right. Nevertheless, diseases can not always be reliably avoided. Then the early recognition and the rapid initiation of countermeasures help. Plant tonics help the trees and can not do any harm.

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