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Although many varieties of blueberries are characterized by high disease resistance, this property does not make the culture completely immune to various ailments and pests. Garden blueberry diseases and their control can be confusing for inexperienced gardeners, which is especially not desirable in cases where treatment must be started 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 distinguish between 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 blueberry growing conditions, for example, with improper watering or a poorly selected planting site.
Viral diseases are spread by various carriers of viruses. Both various pests and harmless insects that were near the injured blueberry bush act as such. Through a cut or scrapping, the virus enters the cells of the plant and, if the culture has weak immunity, it begins to actively multiply, which leads to the development of the disease in blueberries.
But, regardless of the type of disease, at the first adverse symptoms, the treatment process should be started immediately, because due to delay, you can lose not only the seasonal blueberry crop, but also the whole bush. Below, the blueberry diseases divided into types and methods of their treatment are considered in more detail.
Fungal diseases of blueberries and how to treat them
Often the cause of fungal diseases is not enough good 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 to the onset of the disease are 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, on the bark of older branches, brown ulcers with a raspberry-red border form. In the absence of treatment, 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, well-established:
- 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.
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 near-stem circle with a layer of sawdust 5-7 cm thick.
Moniliasis
In moniliosis, also known as fruit rot, fungus-infected blueberries look like they’ve been frozen in the bitter cold. Non-intervention in the course of the disease leads to the fact that the fungus gradually captures other parts of the plant.
The only way to get rid of moniliosis will be the burning of dead parts of the shrub and shoots that have been infected.
Phomopsis
Phomopsis is considered one of the most common diseases characteristic of high blueberries. The risk of its occurrence increases if the late spring was hot and dry. Phomopsis symptoms are in many ways similar to those observed in stem cancer, however, infection does not begin from the leaves, but from the top 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 burned. On the leaves, unaesthetic brown blotches appear. 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 by three times treatment with Tridex, Topsin-M and Skor – before flowering. The procedure should be repeated every 7 days.
White spot
In blueberries, there is also such a disease well-known to gardeners as white spotting. It is characterized by the fact that round spots appear in large numbers 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. Affected leaves soon dry up and fall off.
Leaves must be burned immediately so as not to create additional favorable conditions for the fungus to reproduce. Timely mulching of blueberry bushes will help solve the problem of white spotting.
Antraknoz
Like many leaf diseases, anthracnose in blueberries develops when the bush is waterlogged. Other reasons include poor breathability due to a too dense crown. The foliage of a diseased plant is covered with spots of various sizes, and the berries begin to rot and grow 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.
A witch’s broom
Witch’s broom is an unusual disease of blueberry shoots. The fungus of the genus Taphrina causes shoots to grow intensively on the affected area of the stem, which makes it look like a broom. Fruits and leaf blades on such stems develop very poorly.
The surest way to deal with witch brooms is to cut and burn the affected parts of the bush. However, this is true only if the disease is fungal in nature.
Mučnistaâ rosa
If blueberry leaves dry and turn gray, it is possible that this is the result of powdery mildew. This disease, caused by the activity of the fungus Sphaerotheca mors, appears as a white coating on the leaf plates of the bush, which later darkens and spreads to the fruits and cuttings. The long course of the disease reduces the level of winter hardiness and negatively affects the yield of the plant.
Blueberries can be saved from this disease by timely treatment with such chemical compounds as Sulfaride, Topaz, Bayleton.
double leaf spot
Dry leaves on a blueberry in high season can be a sign that it has been hit by double spot. 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. Infected parts of the plant dry out and, falling from blueberries, are a danger to other crops, as the fungus remains active for a long time. Such shoots and leaves should be burned regularly.
Gray mold
Gray rot, also called botrytis, can cause the foliage and branches of the bush to gradually turn brown, then turn gray and die. The causative fungus botrytis enters the plant tissues through cuts and injuries. The disease can also affect already harvested blueberries that are stored incorrectly.
It is possible to stop the spread of the fungus with the use of fungicides. To do this, blueberries are sprayed with Fundazol up to 3 times with an interval of 1 week.
Viral diseases of blueberries
As already mentioned, in addition to fungal diseases of garden blueberries, there are also viral diseases that threaten the health of the bush.
Mosaic
This disease got its name from the patterns that appear on the leaves under the influence of the virus. Leaf plates turn yellow unevenly, due to which the surface or edges of the sheet seem to be covered with a mosaic ornament. Over time, the foliage may turn completely yellow. 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.
Bush dwarfism
Another viral disease carried by mycoplasma is the dwarfing of the bush. 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 blueberry leaves turn yellow ahead of time, and other symptoms of dwarfism are observed, it is necessary to destroy the bush, and this must be done as soon as possible. Viruses spread no less quickly than fungi and can move to healthy plants if no action is taken in time.
Red ring spot
The disease under this name is characterized by the appearance of rounded spots with a bright red border on the blueberry leaf plates. As the disease progresses, the leaves turn completely red and die. However, in the early stages of the disease, you can try to save the bush by destroying all affected leaves.
Stringiness of branches
The threadiness of the branches can be asymptomatic for a long time and only after years enter the active phase. With this disease, the following symptoms are noted:
- blueberry growth slowdown;
- reddening of the leaves in the initial period of the disease;
- at later stages – twisting and wrinkling of leaf plates;
- the appearance of characteristic thin stripes on young branches.
To date, no cure has been found against the virus that causes filament in blueberries, and therefore all plants with this disease must be disposed of.
Lack of nutrients in the soil
Disturbance in the development of blueberry bushes and reduced yields can occur not only due to disease, but also due to a lack of certain nutrients in the soil.
Thus, the lack of nitrogenous compounds affects the growth rate and color of young blueberry shoots, which first turn pink and then become pale green. The lack of phosphorus is indicated 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 tips of the shoots and their subsequent death.
Blueberry pests and how to deal with them
Some insect pests can cause blueberry connoisseurs no less problems than fungal and viral diseases. The most common pests include:
- heather shooter;
- blueberry moth
- aphids;
- leaflet;
- kidney tick.
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 worth studying in more detail the characteristics of these pests.
Heather shooter
Adults of this butterfly do not harm blueberries, but its caterpillars are known as serious pests. They are easily distinguished from other insects by their black-brown coloration with white patches 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 rather large number of insecticides are effective against shooters, including Fufanon, Aktellik and Kemifos. The spraying procedure is carried out in the spring, before the start 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 there are few caterpillars themselves, then they can be collected manually.
Blue Moth
Blueberry moth is another butterfly whose caterpillars are not averse to feasting on blueberry leaves. These pests are distinguished by the fact that, in addition to ordinary legs, they have four abdominal legs, which are clearly visible in the photo. They have a conspicuous yellow coloration with black lines along the body. The time of appearance of these pests falls on May.
Measures to combat moths are identical to those used against arrowheads. In addition to the above remedies, we can mention the benefits against these pests of drugs such as Kinmiks, Inta-Vir or Iskra.
Flat triangular leaflet
Unlike adult specimens, which attract attention with their snow-white color, leafworm caterpillars 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 brown head. Like all caterpillars, leafworms are leaf pests, but they not only eat foliage, but also wrap themselves in it to protect themselves from birds. For this reason, cobwebs are often noticed on the tops of shoots affected by pests.
This property allows you to get rid of single caterpillars by simply cutting off and destroying twisted leaves. With a large-scale invasion of pests, the bushes are treated with insecticidal compounds.
aphid
Aphids also bring a lot of trouble to blueberry owners. These pests often 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, so the treatment of blueberries from these pests should be carried out in early spring without delay. The following means have shown their effectiveness in the fight against aphids:
- Aktellik;
- 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 advent of spring it moves to the buds, which it eats out from the inside, slowing down the growth of the bush.
You can cope with the tick by early spring treatment of blueberries with Nitrafen, KZM or iron sulfate.
Preventive 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, preference should be given to disease-resistant varieties grown in the same region or country.
- The soil at the landing site should be acidic and fertile, with a sufficient amount of mineral supplements. 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 cut blueberries so that the crown does not thicken too much.
- Damaged, frozen or injured parts of the bush must be removed immediately.
- After leaf fall, all fallen leaves must be destroyed, since pests and pathogens winter well in it.
- If possible, it is worthwhile to carry out the spring treatment 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
While garden blueberry diseases and their control can be a difficult task for the grower, proper treatment can 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 conduct of preventive treatments for ailments and pests.
