Grape diseases with photos and treatment methods

Unfortunately, grapes are susceptible to many diseases, and it's important to detect and treat any affected plants promptly to prevent the entire harvest from being lost. We'll describe the main grape diseases with photos, along with descriptions and treatment recommendations.

Preventative measures are also important; without them, it is very difficult to get a healthy harvest. It is well known that it is much easier to prevent a disease than to spend time and effort searching for effective treatments.

 

 

Mildew

This is the most dangerous and widespread vineyard disease. Also known as downy mildew, this fungal disease attacks all green parts of the vine and the fruit. If left untreated, it can cause significant damage to the entire vineyard. The disease's appearance is immediately apparent on the leaves; if oily, yellow spots appear, sound the alarm—it's mildew. If you look at the underside of the leaf, you'll notice a white, flour-like coating.

The infection spreads quickly in slightly damp and warm temperatures, affecting the leaves, stems, and then the fruit. The grape clusters take on a purple hue, and the berries shrivel and become unfit for consumption. The leaves gradually dry out and fall off, the affected green parts become weak, and the top of the bush dries up. In some cases, the entire bush may die.
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The cause of the disease

Downy mildew is a fungal disease; its spores overwinter in fallen leaves and are resistant to cold. With the arrival of warmth and moisture, downy mildew develops rapidly, forming a germ tube with a single sporangium. Wind or rain carries this sporangium to the grapevine, releasing over 60 zoospores that cause infection.

The disease spreads quickly if temperatures are above 12 degrees Celsius and the air is humid. If temperatures above 30 degrees Celsius and humidity are absent, the disease does not progress. Zoospores wait for favorable weather and, at the right moment, attack the vineyard. The fungus then attaches to the host plant and produces reproductive organs called sporangs, which are visible to the naked eye as white fluff on the underside of leaves. The slightest breeze easily disperses them, and if humidity is high, they immediately begin infecting other healthy vines.

How to treat downy mildew

 

European grape varieties are considered the most susceptible to this disease, while American varieties are the most resistant. If grapes are infected with this fungal disease, all treatments are generally ineffective. Therefore, to protect vineyards, preventative measures are needed to prevent or at least reduce the risk of disease.

Prevention

• treating plants with chemicals before and after flowering. Plant growth products are especially helpful, as they not only improve the yield but also prevent pathogenic flora;
• cleaning and plowing in fallen leaves in autumn and spring, which will destroy the bulk of the embryos;
• high row spacing that is well ventilated, thereby reducing the spread of infection;
• vine garter;
• weeding.

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Treatment methods and drugs

Spray young vineyards with antifungal agents every 10 days. Once the weather warms up, around mid-June, spraying should be done every seven days. Remove diseased branches and leaves and burn them. Infected vines are sprayed with pesticides; antifungal agents should contain copper and zinc.

One of the most effective remedies against mildew is a Bordeaux mixture solution. However, it's important to remember that the solution's consistency should not exceed 3%, otherwise it can damage and burn the leaf surface. The copper sulfate used for spraying should be high-quality, free of any other impurities, and bright blue in color. The solution is prepared with lime, which is slaked during the process. This will ensure better adhesion to the leaves, providing better treatment and prevention for the vineyard.

Since this preparation is easily washed away by rain, treatment and prevention are carried out in four stages:
1. After pruning and tying in the spring, spray not only the bush, but also the ground around it.
2. After flowering.
3 and 4. During the fruiting period at intervals of 10-14 days.

Powdery mildew or powdery mildew

Another fairly common disease, especially in hotter parts of our country. It thrives in warm weather, infecting leaves, berries, and shoots, which become covered with a gray coating. Infected shoots and leaves eventually dry out and fall off, while the berries burst and dry out. It affects almost all grape varieties, including hybrids.

If shoots appear on the bush that are noticeably lagging in growth, their leaves are twisted and curly, covered with a coating similar to gray dust - this is true powdery mildew.

Causes of the disease

The Oidium pathogen overwinters in the buds of infected plants. In the spring, when the first shoots emerge, the bush is already infected, and with low humidity and warm temperatures, the infection develops rapidly. In France, in 1852 and for several years, this disease caused enormous damage to the viticulture industry. Hundreds of plantations were destroyed. Only after it was discovered that it could be treated with sulfur was the disease stopped.

Prevention and control of powdery mildew

• Well-ventilated vineyard formation is the best preventative measure in the fight against fungal diseases.
• Plant varieties with high disease resistance.
• Break off diseased branches and leaves.
• If the damage was severe last year, it is best to treat the bushes after the first shoots appear.

Sulfur-containing products are considered the most effective method against powdery mildew. Spraying is done at the first signs of the disease, and if the disease progresses, repeat spraying is done every six weeks.
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• If small patches of gray bloom appear on the grape clusters, spray with a 2% colloidal sulfur suspension. Afterward, the berries must be rinsed. The final sulfur spraying of the vineyards is carried out two months before harvest.
• Apply sulfur-containing products early in the morning or late in the evening. During the day, hot weather can cause burns to berries and leaves.
• During the fruiting period, it's best to avoid using chemicals that could damage ripe grape clusters. The plant can be treated with a potassium permanganate solution (10 grams of powder per 20 liters of water).
• You can make an infusion: dilute half a bucket of ash in 7 liters of water, let it steep for 24 hours, and dilute it with water one to one before spraying. To improve the solution's adhesion to the leaves, add 100 grams of grated green soap.
• You can purchase ready-made products to help combat powdery mildew: "Talendo" and "Karatan" are effective preventative treatments after flowering, while "Tiovit Jet" can even be used during the fruit ripening period. Let's look at grape diseases, photos, and treatments below.

Drying of shoots

This is not an infectious disease, but it can devastate large grape plantings. It develops rapidly, infecting shoots and covering them with brown and black spots. It can be caused by excessive rainfall or, conversely, a lack of moisture.
The plant is sprayed with a 3% sodium sulfate solution; for varieties sensitive to chemicals, complex fertilizers are applied.

Alternaria

A fungal disease of grape leaves. Initially, light specks appear on the leaves, which then darken until the leaf turns completely black. The disease spreads to the berries, which become coated, wrinkled, and lose their flavor.

How to fight

Treatment should begin immediately, as soon as the disease appears on a few leaves. Remove the bark, remove diseased leaves, and dead shoots. Treat the plant with Bordeaux mixture at the beginning of the growing season. Then, once a week, if necessary. Below, we'll look at grape diseases, including photos and descriptions, treatments, and their berries.

Armillariasis

A fungal disease also known as root rot. The roots become soft and crumbly, the leaves dry out, and the plant gradually dies. There is no specific treatment; the dead plant is dug up and the soil is treated with copper-containing fungicides. Experienced gardeners recommend avoiding planting grapes in infected soil for a year.

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Grape itch mite or felt mite

If you're interested in grapevine diseases, photos, and how to treat leaf bumps, read on. This is called a grapevine mite. It primarily affects grapevine leaves. The mite punctures the leaf, causing raised bumps to form. A small bump, covered in light fuzz, develops on the underside of the leaf, eventually turning dark brown. In red grape varieties, as the disease progresses, the leaves turn red. The spots on the leaves enlarge, merge, and the leaf curls and droops.

In some cases, the disease may stop at the lower leaves. If the weather is rainy, the mites spread to the grape clusters, covering the berries with felt and making them unfit for consumption. The insect reproduces very quickly and also transmits more serious and dangerous grape diseases.

How to fight

To combat felt mites, sulfur-based products or standard acaracid treatments are used. Chemicals that are harmless to bees and humans are also used, such as Tevit, Fufanon, Neoron, and others.

Mealybugs and scale insects

These pests attach themselves to the vine's bark and feed on its sap. This weakens the plant and reduces yield. Fungi develop in the insects' habitat, leading to more serious diseases. The insects overwinter in the shoot bark and emerge in the spring. If you grow grapes and are primarily interested in leaf diseases and treatment, see ALSO: Grape diseases, photos, and treatment options.

How to fight

Spray the bush thoroughly with high pressure to allow the product to penetrate deep beneath the bark and kill pests. Spray in the spring, before the first buds open.

We've explained the various grapevine diseases, shown photos, and recommended leaf treatments. Wishing you a good harvest!