Why does a vine rot and how to save a plant?
The process of rotting grapes, which can affect not only individual clusters and young shoots, but also whole fruitful vines, leads to the loss of more than half of the entire crop. Ignoring the first signs of the disease can lead to infection of nearby healthy plants and ultimately lead to the death of the entire vineyard.
Varieties of rot
The term grape rot usually refers to several varieties of fungal infections. Each type of rot has its own causes and pathogens, but they all share a similar picture of infection.
The defeat of the gray rot fungus primarily affects all green parts of the grapes. Initially, the leaves on the vine are covered with brown spots with a gray tint, which dry out under the influence of sunlight. The color of the affected woody areas of the vine takes on white or light yellow hues. In other cases, the vine is almost completely discolored.
Most of all, berries in the brushes suffer from gray rot - at the time when the grapes are ripe, the leg of the rot rot rot, which leads to malnutrition and lethargy of the grapes. If the fungus spreads further, purple spots form on the berries, due to which the peel darkens and eventually bursts, and the grape itself disappears.
All affected areas are covered with a gray coating, which in appearance resembles cotton wool. The disease of gray rot spreads at a very high speed and leads to the defeat of the entire bush.
Important! Contaminated grapes cannot be used in the manufacture of wine or juice.
The first signs of black rot infection are dry brown spots on the foliage of the grapes. Almost immediately in these areas, the presence of the fungus becomes noticeable. Young berries on the tassels are especially susceptible to this disease. It is during the ripening process that the first visible signs begin to appear - depressions of a light brown hue. In just a few days, the grapes are wrinkled, becoming dark blue, and “pillows” with fungal spores appear between them.
Affected grapes continue to hang on bunches, thereby causing further rapid spread of rot. If untreated, about 80% of the crop can be destroyed by this disease, and in some cases the wood part dies. Even if the rot has touched just a few berries on a branch, such a bunch can no longer be used in further processing.
The causative agents of the white rot fungus can winter in the soil, and in the warm, spring-summer period, from the inside of the soil, move to the shoots of grapes. Important! It is believed that the most dangerous period of infection with white rot is the ripening period of berries: late July - early August. Basically, white rot fungus stops on berries and shoots, the integrity of which is impaired. This can be hail damage or traces of parasites or cracking under the influence of the sun.
The first signs are the appearance of pink small dots under dry weather conditions, and black ones when wet. Dark yellow and / or brown spots appear on the surface of uninfected grapes. The time of grape damage is very short - within a few hours, diseased berries burst, turn brown and dry. Moreover, both one berry and a whole bunch on the bush can suffer.
On the surface of the shoots, which are affected by white rot, gray and brown spots with a dark edging on the edges appear. The bark in such places becomes loose, prone to cracking. However, this type of fungus is not able to destroy the entire vineyard crop, and timely treatment measures can easily stop the putrefaction process.
Find out also why white plaque appears on grapes and how to treat it.
A variety of aspergillosis rot is rare enough, however, this is the fungus that can lead to the death of the entire vineyard. Especially this disease "loves" environmental conditions with high levels of humidity and high temperature. The main signs of the appearance of aspergillus rot in the vineyard are whitish spots on the surface of the berries, which begin to darken over time. Then the grapes crack and become covered with white coating, which then changes color to dark brown.
Why grapes rot: the main reasons
There are several main reasons that provoke the appearance of a fungal infection on grapes:
- Increased humidity due to weather conditions or improper irrigation.
- Lack of natural light and ventilation due to improper selection of a landing place.
- Lack of preventative measures.
- The lack of constant inspection of the vineyard to detect diseases of the initial stages.
What to do and how to treat grapes?
In the event that preventive measures have not been taken, or have been carried out, but not fully, and the vineyard is still affected by fungal diseases, a reasonable question arises as to how to treat infected bushes to prevent further spread of the disease:
- the drug fungicide shows itself well in the fight against all types of rotten diseases;
- with the appearance of gray rot fungi, topsin, euparen or benleit preparations are used;
- with black rot use preparations containing copper, which are also called Bordeaux mixture;
- white rot also stops when processing the vineyard with a 2% Bordeaux mixture, which is also recommended to spray the grapes.
With fungal putrefactive lesions of grapes it is always more difficult to fight than to carry out preventive measures.
That is why it is recommended to adhere to several basic rules:
- The place chosen for planting grapes should be well-lit and easily ventilated - it is better to use high places where there will also be no high humidity, unlike lowlands.
- Mandatory prophylaxis procedures - most often this is spraying with fungicide preparations.
- Conducting regular examinations to help detect diseases in the very early stages.
- The correct watering regime, which will not cause high humidity, should be rare and moderate.
- Do not plant new plants on the site of an early diseased bush - some putrefactive fungi have the ability to remain in the soil for a very long time.
- Complete removal of infected berries and shoots.
The most vulnerable varieties
Due to its structural features, some grape varieties are particularly vulnerable to fungal diseases.
- Pearls of Saba;
- Firstborn of Magarach;
- White raisins;