Blueberry diseases

Blueberry diseasesmay contribute to a reduction in the yield or total lack of fruit, reduced flowering, leaf stains, shoot dieback, and even entire blueberry shrubs. See how to recognizeblueberry diseases , what are their symptoms, as well as methods for fighting diseases and recommended sprays. Here are proven ways to make he althy blueberries in your garden!

Blueberry diseases contribute to a reduction in yielding

Blueberry diseases - prevention

In order to reduce the probability ofblueberry diseases , you should remember about several factors that will reduce the risk of pathogens infecting the plant. When establishing blueberry cultivation, material from certified nurseries should be planted at the recommended spacing that will ensure adequate ventilation of the shrubs. Usually it is every 2 m in a row with 2.5 m spacing between the rows. It is also worth planting varieties less susceptible toblueberry diseasesThen we take care of the proper care of the shrubs, because neglected and weakened plants are more susceptible to diseases.

When planting blueberry bushes or under already growing plants, it is worth using live blueberry mycorrhiza mycelium, which increases the plant resistance to unfavorable conditions and pathogen attacks. Blueberry mycorrhiza also improves plant growth and increases yield. It is worth using it especially in the American blueberry, because in the case of this plant mycorrhiza brings exceptionally good results.

Blueberry fungus diseases

Blueberry gray mold- fungal disease caused by Botrytis cinerea. This fungus hibernates in plant debris in the form of mycelium. In the spring, conidial spores are formed on the blueberry. In rainy and windy weather, the spores infect the young blueberry tissue. If, in addition, the temperature exceeds 15 ° C, the fungus has ideal conditions for infection. Infected flowers begin to die off. Green spots may appear on unripe fruit, and fruit rot over time. Large brown necrotic spots appear on the leaves. The infested blueberry organs become covered with a gray layer of mycelium.

Blueberry powdery mildew- the white-gray coating on the lower side of leaves, flowers and fruits is a symptom of the blueberry disease called powdery mildew. The bloom is formed by the conidial spores and the mycelium of the pathogen. Infected flowers die and the fruit becomes tarnished, losing its consumption value.

Blueberry diseases - gangrene of shoots

Gangrene of blueberry shoots- this disease is caused by the fungus Godronia cassandrae. The symptoms of gangrene can be observed in the lower parts of the blueberry shoots, in the form of necroses, where the bark cracks over time. Nectrotic spots are surrounded by a purple border. As wood grows, the bark becomes silvery gray. The blueberry shoots die. Conidial spores of the fungus spread with rain and infect the shoots where the bark has broken, throughout the growing season.

Blueberry anthracnosis- the symptoms of this blueberry disease appear on all above-ground parts of the shrub. Visible purple necrotic spots appear on the shoots. Longitudinal stripes of bursting bark form in the affected areas. Symptoms only appear when the fruit begins to ripen, resulting in massive rotting of the fruit before harvesting.The fungi hibernate on the shoots and infection lasts all year round. High air humidity and high temperature favor the occurrence of anthracnose.

In the event ofblueberry fungus diseases , cut and destroy infected shoots. Chemical protection is equally important, i.e. spraying the bushes during the flowering and fruit growth period, adjusting the treatments to the prevailing weather conditions and maintaining the grace period (i.e. from spraying to harvesting the fruit). Properly selected fungicidal preparations protect the plant and inhibit the development of fungi. Signum 33 WG or Switch 33 WG will work well in almost all casesof blueberry fungus diseases

To protect blueberries againstfungal diseases, it is also worth using the biological agent Polyversum WP, which successfully replaces chemical fungicides. It is harmless to the environment and has no grace period, which means that we can also spray bushes with fruits already ripening with it.Using Polyversum WP, we can protect blueberries against gray mold and anthracnose. This agent is also suitable for the protection of raspberries, strawberries, fruit trees, vegetables and many ornamental plants. In the case of the American blueberry Polyversum WP, dissolve 1.5 g of the agent in 5 liters of water, which is enough to spray 100 m2 of the crop. I highly recommend!

Blueberry viral diseases

Blueberry threadlike- symptoms of this viral blueberry disease, which is blueberry thread-like nature, are red threads - spots, blueberry shoots and red discoloration on leaves. In addition, the leaves are small and deformed in shape may resemble willow leaves.
Blueberry shock- symptoms are visible in the first year of infection. The leaves and flowers of the blueberry fall off. In the following years, the virus goes dormant. The blueberry produces new growth, but the quantity and quality of the fruit is worse.

Blueberry diseases - leaf discoloration caused by virus infection

Blueberry scald- blueberry leaves falling in early summer, on which marginal chlorosis appears, may be a symptom of a dangerous viral disease which is highbush blueberry scald. Its symptoms may worsen from year to year.
Blueberry ring blotch- blueberry leaves show red ring-shaped spots clearly on the upper side of the leaf. Occasionally, stains may appear on the fruit.
Unfortunately, viral diseases cannot be cured, so if we notice their symptoms, the bushes should be removed (preferably burned after excavation). It is also important to combat vectors, or insects that carry viruses. These are, for example, aphids. Plants infected with viruses must not be harvested for new blueberry seedlings.

nitrogen fertilization of blueberries

Symptoms of blueberrydo not have to result only from an attack of fungi or viruses. There are also fertilization errors. Most often it isnitrogen fertilization of blueberries , which can be achieved by using large doses of acidifying fertilizers. Especially if ammonium sulphate is used for acidification. In addition to high doses of sulfur acidifying the soil, this fertilizer also provides large amounts of nitrogen.
Symptoms of blueberry nitrogen over-fertilization :

• excessive, rapid growth of shoots, as a result of which shoots are bulging and overlapping,
• excessive development of the green parts of the plant, as a result of which the blueberry produces a lot of leaves and little fruit
• increased susceptibility to fungal diseases of fruits and shoots,
• weaker frost resistance.

The only way tohelp plants overloaded with nitrogenis to stop using nitrogen-rich fertilizers and water the plant several times in order to flush excess nitrogen into the deeper layers of the earth (below the blueberry roots) .
To avoid over-fertilization of blueberries with nitrogenin the future:

• avoid using high doses of nitrogen acidifying fertilizers,
• do not sprinkle the fertilizer directly under the plant, and spread the recommended dose evenly on the ground within the crown of the bush,
• use nitrogen fertilizers only in spring or by July at the latest.

Nitrogen fertilizers for American blueberryare best used in spring, and the maximum period of using these fertilizers is from March to July. Nitrogen fertilizers applied at a later date unnecessarily stimulate the plant to grow and hinder its autumn transition to the dormant period before winter.
It is also a good idea to give the plant mycorrhiza to blueberry. The vaccine in the form of live mycorrhiza mycelium will make the plant more resistant, it will better use the nutrients contained in the soil, and it will also increase the tolerance of blueberries to too high soil pH.As a result of the use of mycorrhiza, we will be able to significantly reduce the doses of acidifying fertilizers used,thus reducing the risk of over-fertilization

MSc Eng. Joanna Białowąs