Why are walnuts black on the outside. Walnut diseases. Bacterial root cancer
In this article, I will talk about the main walnut diseases and how to deal with them. There are, strictly speaking, only three of them:
Marsoniosis or walnut brown spot
Marsoniosis affects the leaves, green shoots and fruits of the nut. Symptoms:
- on the leaves - small rounded spots of brown color with a darker brown border. They appear in May. The spots gradually grow and merge. Severely affected leaves fall off;
- on the shoots - the same;
- on fruits - at first small depressed spots of red-brown color. Subsequently, the spots grow and merge. The affected tissue lags behind in growth and begins to crack, sometimes rots and the kernel of the nut turns black. A severely affected ovary often crumbles.
Brown spot is caused by the fungus Marssonina juglandis. The fungus actively develops at high humidity: if the beginning of summer is rainy, walnut crop losses due to disease can be up to 50%.
Control measures
The pathogen overwinters in plant debris and affected shoots - therefore, the most in a simple way the fight is the removal of fallen leaves followed by burning. In addition, effective:
- treatment with a 3% or 3% solution without lime until the buds open;
- for prevention purposes - 2….3 times treatment 1% Bordeaux mixture during the season;
- when signs of damage appear - 3 treatments with Bordeaux mixture or other copper-containing fungicide with an interval of 10 ... 15 days.
It should be noted that the Russian Register of Pesticides does not contain permitted preparations to combat marsoniosis - therefore, it has to be treated by analogy with other similar diseases.
Bacteriosis affects leaves, green shoots, inflorescences and ovary. Appears as small dark spots, which subsequently increase and merge. On the ovary, the spots are quite large and slightly depressed, sometimes they look like a ring, in the center of which there is intact tissue. With a strong lesion, the infection can penetrate to the core, which rots, after which the ovary falls off. Affected shoots turn brown and die.
Ripe nuts themselves are usually not affected, but the pericarp is affected.
The causative agent of the disease is the bacterium Xanthomonas arboricola pv.juglandis, which can spread with wind, insects, pollen, etc. Bacteriosis is aggressive in warm and humid weather.
Control measures
Measures to combat bacteriosis are poorly developed. Early spring spraying with 3% copper or either 1% urea solution has a certain effectiveness. (before bud break). The second spraying is carried out 2 ... 3 weeks after flowering - 1% Bordeaux liquid or 0.3% urea solution is used. Treatments with metronidazole are likely to be effective.
Root cancer manifests itself on the roots in the form of growths and sagging. With a strong defeat, the plant stops developing - especially if the disease develops against the background of a lack of moisture.
The causative agent of root goiter is the soil-dwelling bacillus Agrobacterium tumefaciens. It penetrates the roots through wounds and provokes the active growth of root tissues, disrupting its normal structure.
It is impossible to cure root cancer in any way - therefore, one has to limit oneself to prevention. For planting a walnut, use areas where fruit and other crops that can be affected by root cancer have not grown for many years. In addition, you should carefully consider root system seedlings when buying and before planting. If there are growths on the roots, the affected roots are removed. It is advisable to treat the root system with a 1% solution of acoustic soda (exposure time - 5 minutes), and then rinse clean water. Seedlings with severe damage to the main root or root collar are burned.
Walnut, like any other living organism, can get sick. The main causes of walnut disease can be: improper care, infertile soil, lack of sun rays, excess moisture, nearby groundwater, harmful insects.
Walnut: pests
American white butterfly
Most dangerous insects For walnuts is the American white butterfly. The American white butterfly damages almost all fruit tree species. An insect can develop in two or three generations:
first generation - July-August
second - August-September
the third - September - October.
Caterpillars of the American white butterfly settle on the shoots and leaves of the walnut, and later spread throughout the tree, destroying all the leaves on the tree.
Fighting methods
Methods for controlling the American white butterfly include burning nests (along with caterpillars), using trapping belts to collect and further destroy caterpillars, or using microbiological preparations.
Nut codling moth
Nut (apple) codling moth also damages all fruit tree species. The codling moth develops in two generations:
first - May-June
second - August - September
The first generation of codling moth caterpillars damage the walnut kernel, subsequently the nuts fall off. The second generation of caterpillars settles inside the walnut and eats the cotyledons. One caterpillar can damage several nut fruits, the nuts fall prematurely, which negatively affects the yield.
Fighting methods
To combat the codling moth, pheromone traps are used. These traps contain a certain agent that attracts male codling moths, thereby reducing their numbers and the number of fertilized females.
Also, do not forget to regularly collect wormy carrion and inspect Walnut for the presence of caterpillars.
Nut warty mite
The walnut warty mite is a kind of "minor dirty trick". Its size does not reach even 1 mm. The nut mite damages the leaves before they develop, because. it lives in dormant buds. Recognizing the "work" of the tick is quite simple: it leaves small but numerous dark brown "warts" on the leaves. Acaricides are used to control ticks.
No less harm to the walnut is caused by aphids, sapwood and moth-moth. To combat these pests, special solutions, microbiological preparations and sanitary tree felling are used.
walnut diseases
If we talk about walnut diseases, then brown spotting comes to mind first of all.
Walnut and brown spot
Brown spotting (Marsoniosis) affects walnut fruits, green shoots and leaves. Signs of brown spotting can be considered the appearance of rounded brown spots on the leaves. Affected leaves fall off faster. Brown spotting most often occurs during prolonged rains, when too much moisture accumulates in the soil.
This walnut disease is especially dangerous during the flowering period of the tree. During this period, it is able to destroy up to 90% of the flowers, which will undoubtedly have a negative impact on the crop. As for the affected fruits, they either shrink, crack, rot, or crumble.
Fighting methods
To combat brown spot Walnut(even before the appearance of the kidneys) is treated with 3% Bordeaux mixture. Fallen leaves are burned.
root cancer
Root cancer is a disease that affects the root system of a tree. Cancer enters the roots of the tree through wounds and cracks. A sign of this disease are convex growths. Due to severe damage by root cancer, the walnut may stop its growth and fruitfulness.
Fighting methods
Methods for dealing with root cancer include removing growths on the roots, treating the roots with a 1% solution of caustic soda, followed by washing the tree roots with running water.
Bacterial burn
Bacterial blight is a particularly dangerous disease of the walnut. This disease affects the leaves, shoots, flowers and fruits of the tree. Watery spots can be seen on the leaves and petioles, which later turn black, but the leaves do not fall off for a long time. Ulcers appear on the stems. Shoots wither, buds die. Black spots also appear on the fruits, the walnut kernel turns black and dries up. Liquid droplets appear on the affected areas.
The disease will spread faster in the rainy season. carriers bacterial burn are insects and pollen.
Fighting methods
To combat this disease, copper-containing drugs are used. Severely affected walnut trees are culled, the fruits are destroyed.
So, we looked at the most common walnut diseases, learned what walnut pests exist and how to deal with them. Regular inspection of a tree is the best prevention of any disease.
Walnuts are often used for decoration. landscape design and making a profit. This species produces many fruits, so many grow it for the purpose of selling it. It happens that walnut diseases occur. To deal with them, it is necessary to determine the causes of their appearance, one of them is improper care.
White butterfly - one of the walnut pests
Causes
Gardeners are wondering why walnut diseases appeared. Improper care is the main provocateur of the occurrence of diseases.
Main factors:
- long spring frosts;
- hail or acid rain;
- rainy weather;
- depleted soil.
Not all factors depend on the actions of the gardener, it is impossible to influence the weather, but there are ways to help the tree. Treatment after long rains by special means, and in frosty spring, the nut should be covered with a film.
Brown spots on wood
If black spots with a brown tint appear on green walnuts, then this indicates a fungal disease (Marsonia). The cause of the occurrence is excess moisture. The disease immediately affects young shoots and only then passes to adults. Brown spots appear on the leaves, which eventually cover it completely. If marsonia appears during the flowering period, it will destroy all the flowers and no fruit will appear.
To cope with such a disease, it is necessary to use Bordeaux liquid. With its help, you need to process the tree three times. This tool can be prepared independently, you need quicklime and copper sulfate in equal parts.
You can use drugs that are sold in gardening stores. The most popular are Strobi and Vectra. These funds can be used as a preventive measure.
Brown spots indicate a fungal disease
The danger of bacteriosis for walnuts
Bacteriosis is a walnut disease, due to which a black spot appears on the tree, the leaves fall off. The disease negatively affects not only the plant itself, but also its fruits. With bacteriosis, the fruit ovaries fall off along with the leaves. If the nuts remain on the tree, then the result is fruits of not very high quality.
Bacteriosis can develop in any part of the tree. It occurs due to an excess of moisture or a large amount nitrogen fertilizers in the soil.
To fight the disease, you need to be patient. All fallen leaves are immediately collected and burned. The tree needs to be treated blue vitriol. If the disease has severely affected the nut, then it is better to use Bordeaux liquid for this. Treatment is carried out in two or three stages.
Bacteriosis is manifested by characteristic dark spots
Root cancer is the most dangerous disease of the walnut. It enters through various cracks in the tree. You can detect the affected areas by the bulges that appear on the trunk and root. If a nut is ill with this disease, then it will stop growing and bearing fruit. At the last stage of cancer, the tree dies.
The fight against the disease is to remove growths from the roots. If this is not done, it will be impossible to save the tree. After removing the growths, the places of their formation are treated with a solution of caustic soda, washed with water.
Root cancer can completely destroy a tree
Pests as the cause of diseases
Walnut pests are as dangerous to him as diseases. Sometimes their appearance is the cause of the disease. One of the walnut pests is codling moth. Because of it, the nuts begin to crumble ahead of time.
To prevent its occurrence, it is necessary to regularly remove the nests that the caterpillars create from the tree.
If you see caterpillars or pupae on a tree, they should be immediately removed and burned. You can get rid of the butterfly only with the help of special preparations ("Dendrobacillin" and "Betoxibacillin").
The moth is another insect that attacks the walnut. This parasite feeds on the juice of walnut plants and appears as small brown formations on the foliage. You can get rid of the insect with the help of special means.
Walnut, like any other living organism, can get sick. The main causes of walnut disease can be: improper care, infertile soil, lack of sunlight, excess moisture, nearby groundwater, harmful insects.
In this article, we will learn about the most common diseases of walnuts, about treatment of walnut diseases and find out which insects harm the walnut and how to deal with them. Let's start with perhaps walnut pests.
Walnut: pests
American white butterfly
The most dangerous insect for walnuts is the American white butterfly. The American white butterfly damages almost everything. An insect can develop in two or three generations:
first generation - July-August
second - August-September
the third - September - October.
Caterpillars of the American white butterfly settle on the shoots and leaves of the walnut, and later spread throughout the tree, destroying all the leaves on the tree.
Fighting methods
Control methods for the American white butterfly include burning nests (along with caterpillars), using them to collect and further destroy caterpillars, or using microbiological preparations.
Nut codling moth
It also damages all fruit trees. The codling moth develops in two generations:
first - May-June
second - August - September
The first generation of codling moth caterpillars damage the walnut kernel, subsequently the nuts fall off. The second generation of caterpillars settles inside the walnut and eats the cotyledons. One caterpillar can damage several nut fruits, the nuts fall prematurely, which negatively affects the yield.
Fighting methods
To combat the codling moth, pheromone traps are used. These traps contain a certain agent that attracts male codling moths, thereby reducing their numbers and the number of fertilized females.
Also, do not forget to regularly collect wormy carrion and inspect the walnut for the presence of caterpillars.
Nut warty mite
The walnut warty mite is a kind of "minor dirty trick". Its size does not reach even 1 mm. The nut mite damages the leaves before they develop, because. it lives in dormant buds. Recognizing the "work" of the tick is quite simple: it leaves small but numerous dark brown "warts" on the leaves. Acaricides are used to control ticks.
No less harm to the walnut is caused by aphids, sapwood and moth-moth. To combat these pests, special solutions, microbiological preparations and sanitary tree felling are used.
If we talk about walnut diseases, then brown spotting comes to mind first of all.
Walnut and brown spot
(Marsoniosis) affects walnut fruits, green shoots and leaves. Signs of brown spotting can be considered the appearance of rounded brown spots on the leaves. Affected leaves fall off faster. Brown spotting most often occurs during prolonged rains, when too much moisture accumulates in the soil.
This walnut disease is especially dangerous during the flowering period of the tree. During this period, it is able to destroy up to 90% of the flowers, which will undoubtedly have a negative impact on the crop. As for the affected fruits, they either shrink, crack, rot, or crumble.
Fighting methods
To combat brown spot Walnut(even before the appearance of the kidneys) is treated with 3% Bordeaux mixture. Fallen leaves are burned.
root cancer
Root cancer is a disease that affects the root system of a tree. Cancer enters the roots of the tree through wounds and cracks. A sign of this disease are convex growths. Due to a strong defeat by root cancer, it can stop its growth and fruitfulness.
Fighting methods
Methods for dealing with root cancer include removing growths on the roots, treating the roots with a 1% solution of caustic soda, followed by washing the tree roots with running water.
Bacterial burn
It is a particularly dangerous disease of the walnut. This disease affects the leaves, shoots, flowers and fruits of the tree. Watery spots can be seen on the leaves and petioles, which later turn black, but the leaves do not fall off for a long time. Ulcers appear on the stems. Shoots wither, buds die. Black spots also appear on the fruits, the walnut kernel turns black and dries up. Liquid droplets appear on the affected areas.
The disease will spread faster in the rainy season. Carriers of fire blight are insects and pollen.
Fighting methods
To combat this disease, copper-containing drugs are used. Severely affected walnut trees are culled, the fruits are destroyed.
So, we looked at the most common walnut diseases, learned what walnut pests exist and how to deal with them. Regular tree inspection the best prevention any disease.
Tatyana Kuzmenko, member of the editorial board of the Sobcorrespondent of the online publication "AtmAgro. Agroindustrial Bulletin"
Walnut has long been valued not only for its delicious seeds and oil, but also for quality wood who found wide application V furniture production and arms business. Walnut diseases are diverse and dangerous if they are not dealt with in a timely manner.
If a walnut is sick, urgent action must be taken
Causes of diseases
The ideal place for hazel are regions that:
- average annual temperature 9 °C;
- the temperature in winter does not fall below -28 ° C;
- no frost during flowering;
- relative air humidity 60–80%;
- the annual rate of precipitation is not less than 500 mm, of which a little more than half falls during the growing season;
- occurrence ground water passes at a distance no closer than 1.5–2 meters from the surface of the earth.
Despite the fact that the plant is quite resistant to diseases, ailments are not alien to it. The emerging walnut diseases are associated with the following reasons:
- poor soil;
- improper care;
- poorly chosen landing site;
- deficiency of sunlight;
- excessive moisture;
- groundwater too close.
brown spot
Marsoniosis, or brown spot, affects all parts of the culture. In the first half of May, green foliage is covered with small round-shaped spots that have a brown or light brown color. Small formations merge into a single large spot.
The young foliage marked with the disease begins to crumble. The ovaries are covered with red-brown depressed spots. The fruits on a diseased tree quickly dry out, crack and fall off ahead of time. The kernels from such a plant are unsuitable for human consumption.
If the first half of summer is replete with precipitation, then the disease is unlikely to be avoided, most of the nut crop is lost.
Since shoots and fallen leaves are the wintering ground for the fungus, the first thing to do after harvesting is to burn them. In the spring, until the buds begin to bloom, all shrubs are treated with a 3% Bordeaux composition. So that the disease does not progress, the culture is processed 2-3 more times during the growing season.
bacteriosis
Bacteriosis is caused by the bacterium Xanthomonas. The whole tree is covered with dark spots. auspicious time for infection is warm and damp spring weather.
The disease destroys flowers and young ovaries, nullifies the yield of shrubs. The main carriers are insects and pollen. If the illness occurred at a later time, then the losses will not be so large. Young shoots begin to die off, and wood begins to lose its valuable qualities. Brown spots on the fruit eventually become depressed and change color to black.
In the presence of bacteriosis, the walnut is covered with dark spots.
Once inside the fetus, the bacterium causes rotting of the nucleus. Infected nuts fall to the ground before the full ripening period begins. If the tree has become infected when the fruits have already ripened, then the pericarp takes the whole blow.
The bacterium spends the winter in the foliage, buds and shoots of the culture. Treat the plant before flowering. The fight against them is carried out with the help of urea (1%) or Bordeaux mixture (3%). Re-treatment is carried out after 2-3 weeks.
root cancer
The bacterium Agrobacterium tumefaciens Smith & Townsend causes this disease. The rod-shaped bacterium penetrates through the roots and cracks. The infected tissue cells of the shrub begin to divide much faster, which is why peculiar swells form on the outside on the roots and neck.
A strong infection does not allow the plant to develop, so it begins to lag behind in growth. The disease develops especially quickly with insufficient moisture. At good care bacteria do not affect the development of hazel so much.
Before planting young seedlings, they must be carefully checked for growths. When detected, they are removed, and the roots are disinfected in a solution of caustic soda. When planting, it is necessary to avoid places where they used to grow. vine, fruit bushes and root crops that have suffered a similar infection.
Bacterial burns
Burns affect all parts of the culture. First of all, the disease begins to appear on the foliage and petioles. On closer examination, you can notice watery formations that degenerate into black spots. The leaves don't fall off quite long time. If measures are not taken in time, then in the future ulcers will begin to form on the stems, and the plant will die.
A black spot can also be found on the fruits. Affected kernels begin to dry out. The presence of rain favors the growth of bacteria. When processing hazel, it is first necessary to use preparations containing copper. If the tree is severely affected by the disease, then it should be removed from the site and burned along with the nuts.
insect pests
In addition to diseases, there are at least dangerous pests walnut:
- The American white butterfly is a quarantine pest, an enemy of almost all foliage. fruit crops, including walnut and hazelnut. Pest control is carried out with the help of Bitoxibacillin, Lepidocide and Dendrobacillin.
- The codling moth is a lover of walnut kernels. Making its way inside the fruit, the insect eats out the cotyledons, after which the nut falls off. ahead of schedule. To catch them, trapping belts are used. To prevent them from developing, it is necessary to constantly collect fallen fruits and burn them. It is possible to use insecticides.
- The walnut warty mite, which is only 0.1 mm in size, does not allow the leaves to develop, eating them, while the fruits rarely suffer from it. To determine the presence of a tick, it is enough to examine the leaf plates, which begin to become covered with dark brown warts. To remove the pest, it is necessary to treat shrubs with acaricides.
- Walnut miner moth. It feeds exclusively on the pulp of young foliage, leaving behind a skin, older caterpillars settle on trees, wrap themselves around a leaf and eat it from the inside. To eradicate the pest, Lepidocid and organophosphorus insecticides are used. With a large number of insects, they are destroyed with the help of pyrethroids.
Grow a walnut and get good harvest simple enough. To do this, you need to take care of the plant, protect it and regularly inspect it. Diseases and insects can spread very quickly, as a result, you can lose not only the fruits, but also the plants themselves. That is why the fight against diseases and pests must be carried out in a timely manner.
