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Walnut diseases occur due to improper planting or insufficient care. The culture is hardy, with good immunity, it is affected less often than fruit trees.
The basics of proper wood care
Walnut is a tree that grows in almost every garden. His life expectancy is long. There are specimens bearing fruit for 400 years. In order to prevent the appearance of diseases and pests, you need to competently approach planting and fully take care of the walnut:
- The soil at the planting site must be fertile. It is dug up with humus or compost.
- The groundwater level should not be high. The planting hole must be drained.
- The place is chosen in the sun. The tree does not tolerate shading, it may die.
- After planting, the root collar of the walnut should be level with the soil.
They start planting in early spring; in autumn, planting a nut is possible only in the southern regions. The seedling manages to take root before the first frost.
Complete walnut care consists of several points:
- top dressing;
- organization of wintering.
Pruning begins in spring when the temperature rises to + 4 ... + 5 ° С. Cut out all the shoots that thicken the crown and interfere with its good ventilation. After that, dry and poorly overwintered branches are removed. The procedure is completed by whitewashing the trunk and skeletal branches. Previously, old bark, lichens or growths are removed. The trunk is treated with a solution of copper sulfate, after which it is thoroughly whitewashed.
It is no secret for an experienced gardener that walnuts need abundant watering, especially if the weather is dry. The soil is moistened to the full depth of the roots. During extreme heat, water the tree 2 or 3 times a month. In this case, 3-4 buckets of water are consumed per plant.
You can fertilize the seedling 3 years after planting. If the planting pit was filled according to all the rules, then there will be enough top dressing for this entire period. In the spring and autumn, ammonium nitrate is introduced, in the summer they switch to fertilizing with phosphorus and potassium.
Adult nuts winter well without additional shelter, but young seedlings must be insulated before the onset of cold weather. The trunk circle is mulched with humus to a height of 10 cm.
Important! Walnut tolerates short-term frosts down to -30 ° С.
Walnut diseases and the fight against them
There are a lot of diseases in the walnut, there are dangerous and not very dangerous ones. The duration of fruiting depends on the correct treatment. To correctly diagnose the disease, you need to carefully examine the trunk, leaves and buds of the tree.
Bacteriosis is an infectious disease of the walnut that affects almost all parts of it. It appears as black spots on the leaves, after which they completely dry up and fall off. Young shoots are also covered with brown dots.
The disease spreads during the flowering period, while part of the flowers and ovaries suffers. Then the wood and green shoots die off. The pathogen overwinters in the buds, under the bark and in fallen leaves. In the spring, the infection spreads to the healthy parts of the walnut through freezing holes. Especially rainy weather contributes to this.
For the treatment and prevention of bacteriosis, a 3% solution of Bordeaux liquid and a 1% mixture of urea are used. Treatments are planned 14 days after flowering.
Attention! In the fall, all affected branches and leaves are removed from the site and burned to stop the spread of the disease.
Bacterial burn is one of the worst tree diseases. It manifests itself on leaves, young shoots, affects flowers. Walnut leaves are covered with watery black spots, they dry, but do not fall off. Buds and young shoots die off completely, ulcers appear on the trunk and branches. The peel of the fruit is covered with spots, the kernel completely blackens.
The disease spreads rapidly, especially during the rainy season. Transmitted by pollen and insects.
To combat bacterial burns, preparations containing copper are used. As a preventive measure, treatment is carried out several times in a row:
- in spring, before flowering;
- in the fall, after harvest.
You can use "Tsineb" or "HOM". Spraying is carried out in dry, calm weather.
Warning! Infected trees that cannot be cured should be removed along with the fruit.
This disease is quite rare. The causative agent is a fungus that settles on the inside of the leaf. The affected plates are covered with light green spots with a white bloom. White spot develops in cold and damp weather.
To combat the disease, 1% Bordeaux liquid is used. Walnuts are most often affected in the nursery, where the plantings are too thick.
Brown spot (phyllostictosis)
Fungal disease manifests itself as yellow-brown spots on the leaves of the nut, which lead to tissue necrosis. Dry leaves die off, shoot growth slows down, plant frost resistance is significantly reduced. It is difficult to destroy the fungus, the pathogen hibernates in plant debris and under the bark. In a rainy spring, spores spread to healthy tissues and the disease progresses again.
To get rid of brown spot, walnuts are treated with copper oxychloride or 1% solution of Bordeaux liquid. Spraying is carried out until complete recovery.
Advice! In autumn, all fallen leaves and plant residues should be removed from under the walnut, the soil should be dug up and processed together with the tree.
The disease affects the root system of young seedlings and adult nuts. It manifests itself as growths on the roots, as a result of which the fruiting of the crop decreases or completely stops, winter hardiness worsens, and growth slows down. In advanced cases, the plant dies.
The walnut disease seen in the photo is not easy to spot. It is possible to accurately diagnose root cancer only after digging a seedling.
The causative agent of the disease enters the roots through frost holes, cracks in the bark, or other damage. That is why the trunk and skeletal branches of the tree need careful maintenance. In spring and autumn, all growths, cracks and damaged areas are cleaned to healthy tissue and treated with preparations with copper, caustic soda solution, after which they are covered with garden varnish and whitewashed.
Attention! Deep wounds should be rinsed with a stream of water from a hose, only then covered and whitewashed.
The disease manifests itself on the leaves of a walnut with brown dots, which gradually grow and occupy the entire surface of the leaf plate. As a result, leaf fall begins earlier than usual. In addition, unripe fruits that were affected by marsoniasis also fall off. The yield drops sharply.
At the first signs of the disease, the leaves from the affected tree are removed, the crown is treated with copper-containing preparations. Marsonia spreads in rainy weather. If there is little rainfall, then the cause may be waterlogging of the soil as a result of improper watering. The regime is worth revising, otherwise the whole tree will suffer.
As a prophylaxis of the disease in the spring, the nut is sprayed with the preparation "Strobi", which is bred according to the instructions. Processing is done before bud break. In the summer, Vectra will save you from illness.
Walnut pests and control
A tree weakened by diseases is more often affected by pests, which are not always possible to get rid of quickly. To achieve a lasting result, several treatments are required.
American white butterfly
The most common and dangerous pest of the walnut. The butterfly is white, sometimes it has black or brown spots on its wings. One individual lays up to 1500 eggs per season, the third brood is especially dangerous. Caterpillars pupate and winter on the soil surface, under leaves, in the bark of a tree, in the cracks of the trunk. With the arrival of spring, they begin to harm again.
In one season, the insect gives several generations, so a single spraying does nothing. The butterfly lays its caterpillars on the leaves and young shoots of the nut. Gluttonous young growth quickly eats them and spreads throughout the tree.
In the fight against insects, it is important to destroy the first generation, as the rest cause even more damage. The walnut is examined, the caterpillar nests are removed and destroyed. The procedure is repeated every week. The most effective remedy against the butterfly is the microbiological drug Lepidocide. Processing is carried out before and after the flowering of the walnut.
King nut moth
The pest lays eggs in the leaves of the nut. The lesion can be determined by the presence of dark tubercles on the surface of the leaf plate. Nut moth caterpillars feed on the cell sap of the leaves, eating the flesh from the inside. In case of severe damage, the tree is treated with pesticides:
The preparations are diluted according to the instructions, the treatments are repeated every 15-25 days.
Walnut warty (gall) mite
Fungal diseases of the walnut lead to the defeat of the tree by a gall mite, which attacks it during periods of high humidity. The pest feeds on young foliage and does not harm the fruit. Its presence can be determined by its characteristic features:
- dark brown tubercles appear on the leaves;
- the growth of young shoots slows down;
- the sheet plate spontaneously dries and curls;
- a thin web is visible on the back of the sheet.
Against the tick, acaricides such as "Aktara", "Akarin" are used. The nut is sprayed several times at intervals of 15 days.
The pest settles on a weakened plant. It is simply impossible to notice its presence at the initial stage, since it crawls under the bark. Gradually, the beetle gnaws holes near the kidneys, eats them. Gum flow begins at the tree.
You can protect the walnut from the sapwood. In the spring and autumn, they must trim the crown, cutting out dry and affected shoots. For prevention purposes, the tree is sprayed with insecticides.
The pest is dangerous for the fruit, as the kernels of the walnut will eat away, significantly reducing the yield. Damaged fruits fall prematurely. One caterpillar eats 2-3 nuts. The peak of pest activity occurs in the period from May to September.
Catching the moth can be done mechanically. For this, traps with pheromones are used, into which males fall. They are removed and destroyed, which significantly reduces the number of offspring. In case of severe damage to the tree, drugs with viruses are used that cause inflammation of the granulomas in the pest.
Important! For prevention purposes, all fallen fruits are collected and destroyed in order to prevent the spread of the moth.
The pest settles on the underside of the leaf plate, sucks the juice from the tissues. As a result, the leaves curl, die off and fall off. The nut weakens quickly and slows down growth. The fruits do not have time to ripen at the right time and also fall off.
Aphid infestation can be observed after rain. First of all, young leaves suffer, which leads to their diseases. At this time, the walnut is sprayed with preparations "Karate" or "Decis". Treatments should not be carried out during flowering, so as not to destroy the bees. The interval between spraying is 15-25 days. After rain, the treatments are repeated.
Prevention of walnut diseases
As a prevention of diseases and pests of the walnut, it is important to properly care for the plant. Particular attention is paid to the tree in spring and autumn.
In early spring, the soil under the walnut is loosened, granular mineral fertilizers are laid out in order to increase the plant's immunity to diseases. Pruning is mandatory. Before bud break, prophylactic treatments are carried out with complex preparations for all sorts of diseases and pests.
In summer, the area of the trunk circle is kept clean, timely removing weeds in order to prevent pests from multiplying in them. After all, it is they who transfer various fungi and viruses to the plant.
In the fall, the nut is re-sheared, after which the crown is sprayed with approved drugs for prevention. Before frost, all fallen leaves, fruits and plant debris are removed in order to reduce the number of wintering pests. When a stable subzero temperature is established on the street, they dig up the soil under the nut. Some of the pupated pests will die. To increase the immunity of the tree and its winter hardiness, experienced summer residents are advised to carry out late water-charging watering. It is planned for the end of autumn, before the frost has begun.
Attention! All garbage is removed from the site and burned. During spraying, attention is paid to the soil under the walnut, it is also treated.
Walnut diseases lead to significant loss of yield, so they should be avoided. For this, the tree is not left unattended for a long time and is grown in accordance with the recommendations of experienced gardeners.