Help the development of the site, sharing the article with friends!
Grapevines (Vitis) are not only very decorative, they provide shade, beautify house walls and, with a bit of luck, produce delicious grapes year after year. Yellow, green, blue or pink, home-grown grapes simply taste best. However, vines can suffer from numerous, more or less stubborn diseases. It is then important to react quickly and take appropriate countermeasures to prevent the spread or the death of individual plants.
Common diseases of grapevines
Some wine diseases can cause great damage and severely affect the vines. Others, on the other hand, do not pose a great danger. They can usually be recognized by the leaves and fruits of the vines and can often be clearly assigned to the different wine diseases. This makes it possible to combat them quickly and in a targeted manner. However, effective control is often only possible through good prevention. But what are the most common grapevine diseases and what is the most effective way to combat them?
Powdery and downy mildew
powdery mildew
- One of the most dangerous diseases of the grapevine
- Growth on walls and walls can favor an infestation
- Disease affects all green parts of plants as early as spring
- Fungus develops particularly well in dry weather
- Usually recognized relatively late
- Only when grapes do not develop properly, turn dark and burst open
- Other symptoms are dark gray discoloration on leaves and annual shoots
- Fungus overwinters in buds and breaks out again next year
Wrong mildew
- No less dangerous
- In contrast to powdery mildew, it prefers persistent moisture
- Occurs primarily where it is not sheltered from rain
- Develops on the undersides of leaves
- Appears in the form of a white mushroom lawn
- The grapes can also be affected
Both types of powdery mildew can be controlled in a similar way. You should start with the sprouting by spraying the vine with sulphur. Used preventively, several times a year and over several years, it can prevent infection. The sulfur destroys almost all insects in the vine, unfortunately also the useful ones. In the case of an initial infestation, all infested parts of the plant should be removed and the vines thinned out.
Red Burner
The so-called red burner is a fungal disease that affects both leaves and inflorescences. It occurs in particular on stony, humus-poor, shallow and dry slopes.
- First symptoms visible after about 2-3 weeks
- Around the end of May to the beginning of June, the leaves are affected in the form of spots
- Spots on light varieties are yellowish to brownish with a light green edge
- For red wines, ruby red with a yellow edge
- As the disease progresses, affected areas turn brown and dry up
- Partly in July/August a renewed infestation is possible
- After frequent rainfall, risk of renewed infestation is particularly high
- Infection of the inflorescences is also possible
- Affected inflorescences dry up
Most grape varieties are susceptible to this disease. As a result, vines should be treated with approved pesticides as a preventative measure, but at the latest when infestation begins. The first treatment should be carried out from a shoot length of approx. 10 cm or from 4-5 fully developed leaves. It is best to spray just before precipitation or immediately after. A second and third treatment is usually necessary, at intervals of 8-10 days.
tip: The fungus overwinters in the vine leaves lying on the ground. If this is not completely removed, the risk of infection in the next year is very high.
black spot disease
Black spot disease, also known as shoot necrosis, is also caused by a fungus. It affects all living, green parts of plants and is particularly evident on shoots and leaves. An infestation usually occurs from June and is favored by a low pH value in the soil, too much moisture and too much nitrogen supply. It is most common in regions with high rainfall.
- First signs to recognize on the still growing leaves
- They have slight bronze-like discolorations
- They usually go unnoticed
- Visible symptoms appear later
- In the form of punctiform brightening and deformations on the leaves
- Beneath affected, woody parts of the vine, scab-like necrosis forms
- Dying plant tissue is called necrosis
- In principle, they can also occur on all green parts of plants
- Infected grapes turn dark blue to black
- In the case of a severe infestation, the shoots close to the trunk become crippled
- In winter, the fungus grows into previously undamaged parts of the bark
- From February, small black dots can be seen in the white parts of the bark
- Dots are the spore stores of the fungus
Since this fungus overwinters in annual and perennial wood as well as on the bark, it is important to cut out all affected parts. As a rule, it is advisable to rejuvenate the vine below the affected wood. The trunk is then rebuilt in this area.
The infested wood removed from the wine should be disposed of with household waste, but at best it should be burned. In addition, fungicides can be used for treatment, which are applied as far as possible before precipitation or in wet and cold weather. The first treatment begins when the buds break open or when the first green shoot tips become visible. Another treatment should be carried out after about ten days.
tip: Approved plant protection products based on sulfur are very suitable for the first sprouting spray.
green rot
Green rot is a rotting agent that occurs on vines in warm, humid weather and mainly in years when the berries ripen very early. Grapes that have been injured or damaged for various reasons are affected. Be it by wasps or birds, hail, crushed, burst berries, worm infestation or sunburn.
- Affected ripe berries on the wine turn light brown
- A little later, first white, then blue-green pustular spore deposits can be seen
- Green rot often occurs together with botrytis (grey mold) and vinegar rot
- Affected grapes must be removed
- Otherwise they can endanger the reading material
- There are no fungicides that are sufficiently effective against green rot
As a result, the prevention also of particular importance in combating this disease. This means that you should avoid damaging the grapes as much as possible and ensure good ventilation of the vines by regularly cutting the wine. If necessary, a partial defoliation of the grape zone can be useful. In addition, the risk of infection can be reduced by combating botrytis.
gray mold
Gray mold is one of the wine diseases caused by fungi, especially those of the Botrytis genus, and occurs primarily in damp and cool late summers. Wine varieties that form very dense clusters are particularly susceptible. However, it is relatively rare to find in sheltered places.
If there is an infestation, it shows up as black-brown discolored areas on young shoots, leaves, stems and grapes. Leaves and grapes wither and rot. Affected buds also turn brown. Infested plant parts should be cut out consistently to prevent spread. In addition, leaves and shoots are repeatedly dusted with rock dust.
tip: As a preventive measure, to protect against diseases, sufficient planting distances should be ensured and the wine should be regularly blended. Plant strengthening agents make the wine more resistant.
vinegar rot
Acetic acid bacteria and yeast fungi, which ensure that the pulp and juice of the grapes ferment, are responsible for the formation of vinegar rot. It is the result of previous injuries to the grapes, and infection only occurs when there is sufficient sugar and moisture on the grape skin.
- Affected grapes give off an intense vinegar smell
- In the final stage they turn reddish-brown
- A short time later they are hollow
- Commonly found in and on the berries are vinegar flies
- They can contribute to the spread of this disease
- Direct control is not possible with vinegar rot
- The best control is good prevention
- Preventive measures are similar to those of green rot
tip: Both whole grapes and parts of grapes on the wine that are affected by green or vinegar rot should not be removed too early, as this would increase the infection pressure on the remaining berries.
black rot
Black rot is also one of the wine diseases. Similar to green rot and vinegar rot, it also occurs primarily in areas where there is increased precipitation in spring and early summer. Leaves and shoots of affected vines have small, sharply defined, light spots with a dark brown border. Small, shiny, black dots, the fruiting bodies of the fungus, can be seen on dead tissue. The grapes initially have pale spots, which later turn reddish-brown and finally black and die off. Even unripe berries have light reddish-brownish spots, they dry up within a few days. What remains are fruit mummies on which the fruiting bodies sit, in which the fungus overwinters.
There are no effective approved plant protection products against black rot. The effect of copper and sulfur is also limited. A particularly high risk of infection comes from neglected, no longer cultivated vineyards nearby. In order to effectively combat black rot, clearing such areas is recommended. In addition, fruit mummies should be sorted out and disposed of during the harvest, and regular pruning should ensure good ventilation of the vines.
Esca disease
Several fungi are involved in the outbreak of Esca disease. Symptoms of this disease can occur throughout the growing season, but mainly from midsummer and in older vineyards. The clinical picture can be acute or chronic.
- In acute form, leaves and grapes suddenly die and dry up
- In the chronic, between the main veins of the leaves, light spots of different sizes
- Mottled areas will later die off
- A narrow green stripe usually remains along the larger leaf vein
- Green stripes in white wine varieties with a yellow border, in red varieties, wine-red
- Leaves dry up and fall off prematurely
- Brownish-violet to gray spots can be seen on the grapes
- Berries that are still young shrivel
There are no special means of combating it either. Trunk rehabilitation can be useful, especially for young vines. To do this, they are cut back into healthy wood in winter. Any clippings should be disposed of with household waste or incinerated. As with most wine diseases, prevention is the best protection against Esca disease.
