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Although many blueberry varieties are characterized by high disease resistance, this property does not make the crop completely immune to various ailments and pests. Diseases of garden blueberries and the fight against them can be confusing for inexperienced gardeners, which is especially not desirable in cases where it is necessary to start treatment immediately. In order not to waste time, faced with the first signs of blueberry disease, it is necessary to figure out what ailments this culture has.
Classification of blueberry diseases
At the moment, as such, there is no official classification of blueberry diseases. However, for convenience, many gardeners differentiate all known ailments inherent in this plant into two conditional groups:
- fungal;
- viral.
Fungal diseases, as the name suggests, are caused by fungal organisms. Most often, they develop as a result of violations of the growing conditions for blueberries, for example, with improper watering or poorly selected planting site.
Viral diseases are spread by various vectors of viruses. These are both various pests and harmless insects that were near the injured blueberry bush. Through a cut or scrapping, the virus enters the plant cells and, if the culture has weak immunity, begins to actively multiply, which leads to the development of the disease in blueberries.
But, regardless of the type of disease, at the first unfavorable symptoms, the treatment process should be started immediately, because due to delay, you can lose not only the seasonal blueberry harvest, but also the whole bush. Below is a more detailed discussion of the types of blueberry disease and methods of their treatment.
Blueberry fungal diseases and how to treat them
Fungal diseases are often caused by insufficient care. However, even well-groomed plants are not immune from such ailments, and therefore it will not be superfluous to familiarize yourself with the symptoms of such diseases.
Stem cancer
The disease, contrary to its name, affects not only the stems, but also the leaves and petioles of blueberries. The first signal for the onset of the disease is small red spots at the base of the leaves on young shoots, which increase in size over time and cause them to die off. Later, brown ulcers with a raspberry-red border form on the bark of the older branches. If untreated, their number grows until the plant dries up.
Fortunately, stem cancer is treatable. To prevent the disease from spreading throughout the bush, it is worth regularly cutting off the infected parts of the plant and burning them. In addition to this, it is necessary to treat blueberries with antifungal and copper-containing drugs. Among them, the following have proven themselves well:
- Fundazol;
- Topsin;
- Euparen (0.2% solution).
Treatment with these substances should be carried out 3 times with an interval of 7 days before budding and the same number of times after picking berries.
Mummification of berries
Often, the fruits and leaves of blueberries are affected by the fungus Monilinia vaccinii-corymbosi. Berries that have been exposed to it develop as usual, but do not reach ripeness and dry out prematurely. The leaves and young shoots of the plant, in turn, turn black and fall off.
The early spring treatment of blueberry bushes with urea will help to cope with this disease. It is also useful to mulch the plant by sprinkling the trunk circle with a layer of sawdust 5 - 7 cm thick.
Moniliosis
In moniliasis, also known as fruit rot, blueberries that are infected with the fungus look like they were frozen in extreme cold. Non-intervention in the course of the disease leads to the fact that the fungus gradually invades other parts of the plant.
The only way to get rid of moniliosis is to burn dead parts of shrubs and shoots that have been infected.
Phomopsis
Phomopsis is considered one of the most common diseases inherent in high blueberries. The risk of its occurrence increases if the late spring is hot and dry. The symptoms of phomopsis are in many ways similar to those observed in stem cancer, but infection begins not from the leaves, but from the upper part of the shoot. Young blueberry branches up to 45 cm in size begin to dry out and curl. Under the influence of the fungus, the bark on the branches becomes brown and seems to be burnt. Unaesthetic brown blotches appear on the leaves. The lack of timely measures to protect blueberries from this disease leads to the death of the shrub.
Removing and burning damaged shoots will be the first step in treating blueberry Phomopsis. Good results are obtained three times with Tridex, Topsin-M and Skor before flowering. The procedure should be repeated every 7 days.
White spot
Blueberries also have such a disease well known to gardeners as white spot. It is characterized by the fact that large numbers of round spots appear on the leaves of the shrub, the color of which varies from whitish to reddish-brown. The size of the spots ranges from 4 to 6 mm. The affected leaves soon dry up and fall off.
The leaves must be burned immediately so as not to create additional favorable conditions for the fungus for reproduction. Timely mulching of blueberry bushes can help solve the problem of white spotting.
Anthracnose
Like many leaf diseases, blueberry anthracnose develops when the bush is overmoistened. Other reasons include poor air permeability due to a too dense crown. The foliage of the diseased plant becomes covered with spots of different sizes, and the berries begin to rot and overgrow with an orange bloom.
You can eliminate the fungus that causes anthracnose with the help of various fungicides:
- Speed;
- Switch;
- Signum;
- Rovral;
- Topsin-M;
- Euparen;
- Polyversum.
Using these products 2-3 times during the flowering period will help preserve the crop and prolong the health of the bush.
Witch's broom
The witch's broom is an unusual blueberry shoot disease. The fungus of the genus Taphrina causes shoots to grow vigorously on the affected area of the stem, which makes it look like a broom. Fruits and leaf plates on such stems develop very poorly.
The most reliable way to deal with witch brooms is to trim and burn the affected parts of the bush. However, this is true only if the disease is fungal in nature.
Powdery mildew
If the leaves on blueberries dry and turn gray, it is quite possible that these are the consequences of powdery mildew.This disease, caused by the activity of the fungus Sphaerotheca mors, manifests itself as a white bloom on the leaf blades of the bush, which later darkens and spreads to fruits and cuttings. The long course of the disease reduces the level of winter hardiness and negatively affects the yield of the plant.
Timely treatment with such chemical compounds as Sulfaride, Topaz, Bayleton can save blueberries from this ailment.
Double leaf spot
Dry leaves on blueberries during high season can be a sign that they are double-spotted. At the end of spring, small smoky spots 2 - 3 mm in size appear on the leaf plates of the bush. At high humidity in July-August, they increase in size up to 15 mm and capture the entire plant. The infected parts of the plant dry out and, falling off the blueberry, pose a danger to other crops, since the fungus remains active for a long time. Such shoots and leaves must be burned regularly.
Gray rot
Gray rot, also called botrytis, can be the reason that the foliage and branches of the bush gradually turn brown, then turn gray and die off. The botrytis fungus enters the plant tissue through cuts and injuries. The disease can also affect harvested blueberries that are not stored properly.
It is possible to stop the spread of the fungus using fungicides. To do this, blueberries are sprayed with Fundazol up to 3 times with an interval of 1 week.
Blueberry viral diseases
As already mentioned, in addition to fungal diseases of garden blueberry, there are also viral diseases that threaten the health of the bush.
Mosaic
This disease gets its name from the patterns that appear on the leaves under the influence of the virus. The leaf plates turn yellow unevenly, due to which the surface or edges of the leaf seem to be covered with a mosaic ornament. Over time, the foliage may turn yellow completely. Such a virus not only spoils the appearance of blueberries and its taste, but also poses a danger to other crops, as a result of which it is necessary to get rid of the diseased bush.
Dwarf bush
Another viral disease carried by mycoplasma is bush dwarfism. The virus inhibits the growth of blueberries, due to which the branches develop incompletely, and the berries become smaller and have an unpleasant taste. In addition, the crown of the bush changes the color of the foliage even before the onset of autumn. Therefore, if the leaves of blueberries turn yellow ahead of time, and other symptoms of dwarfism are observed, it is necessary to destroy the bush, and this should be done as soon as possible. Viruses spread just as quickly as fungi and can spread to healthy plants if not addressed in time.
Red ring spot
The disease under this name is characterized by the appearance of round spots with a bright red border on the leaf plates of blueberries. As the disease progresses, the leaves turn red and die completely. However, in the early stages of the disease, you can try to save the bush by destroying all affected leaves.
The threading of the branches
Filamentous branches can be asymptomatic for a long time and only after years enter the active phase. With this disease, the following symptoms are noted:
- slowing down the growth of blueberries;
- reddening of the leaves in the initial period of the disease;
- in later stages - twisting and wrinkling of leaf plates;
- the appearance of characteristic thin stripes on young branches.
To date, no treatment has been found against the virus that causes filamentousness in blueberries, and therefore all plants with this disease must be disposed of.
Lack of nutrients in the soil
Disruption in the development of blueberry bushes and a decrease in yield can occur not only due to disease, but also due to a lack of certain nutrients in the soil.
So, the lack of nitrogenous compounds affects the growth rate and color of young blueberry shoots, which first turn pink and then turn pale green. The lack of phosphorus is evidenced by the inability of the plant to bloom, as well as the base of the leaves, which acquires a purple color. Sulfur deficiency leads to blackening of the top of the shoots and their subsequent death.
Blueberry pests and how to deal with them
Some insect pests can cause blueberry connoisseurs as much of a problem as fungal and viral diseases. The most common pests include:
- lancet heather;
- blue moth
- aphids;
- leaflet;
- kidney mite.
These insects, even in small clusters, can significantly impair the yield of blueberries and even provoke the death of the plant if their activity is ignored for a long time. Therefore, it is worthwhile to study in more detail the features of these pests.
Sagittarius heather
Adults of this butterfly do not harm blueberries, but its caterpillars are known as serious pests. They are easy to distinguish from other insects by their black-brown color with white blotches and an elongated body covered with short hairs. These pests appear throughout the summer and actively eat the leaves and young shoots of the plant. A fairly large number of insecticides are effective against lancet, including Fufanon, Aktellik and Kemifos. The spraying procedure is carried out in the spring, before the beginning of the growing season, and in the summer if the number of pests is too large. If there are no adult insects on the site, and the caterpillars themselves are few, then they can be collected by hand.
Blue moth
The blueberry moth is another butterfly whose caterpillars are eager to feast on blueberry leaves. These pests are distinguished by the fact that, in addition to the usual legs, they have four abdominal legs, which are clearly visible in the photo. They have a conspicuous yellow color with black lines along the body. The appearance of these pests is in May.
Control measures for moths are identical to those used against oozera. In addition to the above remedies, one can mention the benefits of drugs such as Kinmix, Inta-Vir or Iskra against these pests.
Triangular flat leafworm
Unlike adult specimens, which attract attention with their snow-white color, the caterpillars of the leafworm are light green and hardly noticeable against the background of foliage. On the sides of the body and on the back, these pests have darker stripes, and black spots can be seen on the head of a brown shade. Like all caterpillars, leafworms are leaf pests, but they not only eat the foliage, but also wrap themselves in it to protect them from birds. For this reason, cobwebs are often seen on the tips of the shoots affected by pests.
This property allows you to get rid of single caterpillars by simply breaking off and destroying curled leaves. With a large-scale invasion of pests, the bushes are treated with insecticidal compositions.
Aphid
Aphids also bring a lot of trouble to blueberry owners. These pests are more likely to accumulate on young shoots, starting in May. In addition to the fact that aphids drink the juice from the plant, they also serve as carriers of various viral diseases, therefore, processing blueberries from these pests should be carried out in early spring, without delay. The following agents have shown their effectiveness in the fight against aphids:
- Actellik;
- Calypso;
- Karate.
Kidney mite
This pest has a very small size - up to 0.2 mm.Together with the larvae, it hibernates in the axils of blueberry leaves, and with the arrival of spring it moves to the buds, which it eats from the inside, slowing down the growth of the bush.
You can cope with the tick by early spring processing of blueberries with Nitrafen, KZM or iron vitriol.
Prevention measures
In order for diseases and pests to annoy blueberries as rarely as possible, it is worth listening to a few simple tips:
- When choosing a blueberry variety for planting, you should give preference to disease-resistant varieties grown in the same region or country.
- The soil at the planting site should be acidic and fertile, with a sufficient amount of mineral additives. In addition, the soil must be moist, since blueberries are a moisture-loving plant.
- Blueberry bushes should not be more than 2 meters apart.
- It is advisable to regularly inspect and trim the blueberries so that the crown does not thicken too much.
- Damaged, frozen or injured parts of the bush must be removed immediately.
- After the fall of leaves, all fallen leaves must be destroyed, since pests and pathogens winter well in it.
- If possible, it is worthwhile to carry out spring processing of blueberries with Bordeaux liquid, and in the fall after harvesting, spray the plant with fungicides, so the bush can be protected from pests and diseases.
Conclusion
Although garden blueberry diseases and their control can be challenging for the grower, a competent approach to treatment will help keep the plant healthy. However, it is much easier to prevent a disease than to treat it, and therefore it is especially important not to ignore the timely implementation of preventive treatments for ailments and pests.
