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9 Common Grape Diseases and How to Treat Them

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Introduce

Grapes are one of the most delicious fruits to eat, but they can also be a pain when it comes to dealing with diseases. Grape diseases are disastrous if you are a winemaker. Bacteria and fungus cause the most common grape diseases.

This blog post is going to go over some common grape diseases and how you can treat them.  But before that, let’s see the importance of grapes in the first place.

 Why Grow Grapes?

According to studies published in research gate, the Worldwide, grape value is more than $68 billion (USD) with over 7.1 million ha in production.  Grapevine fruit, seeds, skins, and leaves provide numerous health benefits. Let’s look at some of the benefits that come along with grapes:

  • They are rich in Vitamin C, which helps to keep diseases at bay.
  • They are dense in antioxidants. Antioxidants are materials that defend your cells from free radicals, which may cause heart disease, cancer, and other diseases. Free radicals are molecules that your body produces when it digests food or when you are subjected to tobacco smoke and radiation. 
  • They are the source of vitamin K, which is crucial for healthy bones and blood clotting. 

Other benefits include processing grapes into jams, juices, vinegar seed oil, and grape seed extractor.

However, several grapevine diseases can reduce the vitality of your plant. Let’s look at some of the signs of grape diseases that should alarm every grapevine farmer.

Signs of Grape Diseases

  • Weak stems
  • Short shoots
  • White fungal mats under the bark
  • Unproductive vines
  • Rapid wilting

If you detect random alteration on your grape tree, don’t wait until you can’t handle it anymore.

Here are nine common grape diseases and how to treat them.

1. Powdery Mildew

Powdery mildew is one of the never-ending fungal problems on your grapes and is one of the world’s most common grape fungal infections.

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Cause

 Caused by the fungal disease Erysiphe necator and appears as ash-grey to powdery white growth on your tree’s green tissue. It affects both table and wine grapes. If left unchecked, it can cause significant crop losses and damage wine quality.

Diseased leaves look yellowish gray, hazy, or powdery white. Petioles, clustered stems, and fresh shoots twisted. Grapes can become infected till their sugar level reaches around 8%.

If your grapes get infected when young, their skin can crack, causing the berries to dry up or decay. Once older grapes become infected, a netlike pattern often forms on their surface.

Treatment

Potassium bicarbonate–Just like baking soda, this has the added benefit of really removing powdery mildew after it has established itself. Potassium bicarbonate is a chemical fungicide that immediately kills powdery mildew spores.

2. Downy Mildew

This fungus is an obligatory disease that can infect all portions of your grapevine that are green.

This disease’s symptoms are commonly confused with those of powdery mildew. 

Infected leaves have pale yellow-green lesions that turn brown with time. Leaves that are severely diseased frequently drop early.

Infected leaves, tendrils, and stalks frequently curl and create a shepherd’s curve before becoming brown and dying.

Young grapes are more vulnerable to infection, and they are coated frequently with the fungus’s white fruiting structures. Infected white cultivars’ elder grapes may turn dark grey, whereas dark cultivars’ grapes turn reddish pink.

Cause

It is a dangerous fungal disease of grapes that can cause significant crop loss. Plasmopara viticola is the fungus that causes it. All green sections of the vine, particularly the leaves, are attacked by the infection.

Treatment

Mix one tablespoon baking soda and one-half teaspoon liquid, non-detergent soap in one gallon of water and spray thoroughly on your plant

3. Greenria Bitter Rot

This fungus can infect all green portions of the vine, including leaves, young shoots, and grapes.

Older leaves and ripe fruit, on the other hand, are not affected. In late April (spring), leaf infections emerge as red patches on the upper leaf surface.

The round spots grow and turn tan to brownish, with noticeable dark borders. In the middle of these spots, little, pinpoint black fruiting structures of the fungus frequently grow.

Cause

 It is caused by the fungus Greeneria uvicola.

Treatment

remove sick fruit or mummified grapes, as well as cankers on branches. Also, cut and eliminate any fire-blight-infected wood sprouts, as they can reinfect the tree.

4. Black Mold Rot

It is a deadly disease that affects both cultivated and wild grapes. The infection is most lethal during the hot, wet seasons. It attacks all of the grape’s green portions.

When temperatures rise above 30°C, black mold becomes more prevalent.

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Cause

 It is caused by the fungus Guignardia bidwellii.

Treatment

The ideal time to treat this disease is between bud break and four weeks following bloom. you can also use captan or any other fungicide of your choice

5. Botrytis Bunch Rot 

Just before harvest, one or more grapes in a cluster show signs of deterioration. The rot may spread to include the majority of your grapes in a cluster.

The fungus subsequently generates spores (conidia), which are responsible for the disease’s spread.

Cause

The rot is caused by the fungus Botrytis cinerea

Treatment

Ensuring optimum air circulation through canopy management and leaf removal is an essential cultural strategy for Botrytis bunch rot management.

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6. Rust

The disease can result in early leaf fall, poor growing conditions, and

decreased fruit output and quality.

This disease will attack your grapevines, generally harming the leaves,

although it can also break the fruit and stems, causing crop damage.

Cause

by the fungus Phakopsora euvitis.

Treatment

When the buds on your grape plants begin to open in the spring, reapply the sulfur fungicide.

7. Anthracnose Fungus

It is a fungal infection that affects the leaves and twigs of plants in the spring when the temperature is chilly and moist. The cool, rainy weather makes ideal circumstances for the spores to spread.

Cause

It is caused by  the fungus Colletotrichum lagenarium

Treatment

The first step in controlling anthracnose is to practice good sanitation. You are also supposed to collect and dispose of all sick plant parts, especially leaves and twigs, from the ground or around the plant.

8. Alternaria Blight

This disease Causes leaf drying and defoliation. Signs occur as deep brown spots on affected grapes and bunch stalks below their connection to the stems.

Cause

It is caused by the fungus Alternaria cucumerina.

Treatment

To avoid future outbreaks, apply fungicide directly on diseased plants, as well you can increase hygiene and crop rotations.

9. Crown Gall

This bacterial infection is especially harmful to your vinifera grapes. The most noticeable symptom is fleshy galls on the lower trunk near the soil. Galls can grow up to 3 feet high on trunks.

Cause

It is caused by a bacteria called Agrobacterium tumefaciens.

Treatment

The most successful treatment currently available is removing the gall and the bark tissue surrounding the gall.

Conclusion

The grape disease is a significant worry, particularly for grape farmers. If you see any concerning symptoms in your grape tree, contact a tree care specialist. If you ignore your grape tree ailment, it has the potential to grow fatal, infect other grape trees, and spoil your produce.

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If you’re looking for the finest strategies to protect your grape orchards, look no further because Eyouagro got your back. We have vineyard side netting, vineyard bird netting, that will protect your grape garden by keeping insects and birds away, as they play a significant part in spreading these diseases. You can estimate the quantity of the grape netting you need here.

We also provide a variety of items to meet your needs. Our main goal is to make farmers’ lives easier and assist them in taking care of their crops.

If you want to know more information or make an inquiry, then visit our website at EyouAgro or send us an email at [email protected].

Kevin Lyu
The Author >>
Kevin Lyu
Hey, I’m Kevin Lyu, the founder of Eyouagro.com , Family-run business
An expert of agriculture protection textile specialist .
In the past 24 years, we have helped 55 countries and 150+ Clients like farms, orchards , vineyards to protect their plants. The purpose of this article is to share with the knowledge related to agriculture growing protection for making the plant healthier and stronger.
We are at your disposal for any technical or commercial information

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