White, gray, top and other rot on cucumbers in a greenhouse: treatment, what to do

Cultivation of cucumbers in protected ground includes the prevention and control of various diseases that lead to rotting of plants and fruits. The most common ones:

white rot on cucumbers;
grey rot;
fusarium root rot;
late blight root rot;
fungal and bacterial fruit rot;
physiological vertex rot.

Why do cucumbers rot in a greenhouse

The main causative agents of putrefactive diseases are fungi. High humidity of protected ground and unstable temperature provoke the spread of infection. Water evaporated by plants is constantly retained inside the greenhouse structure. Excess moisture deposited on the stems and leaves becomes a favorable environment for the growth and development of fungi

Reasons:

irregular ventilation;
Violation of ventilation due to dense plantings and improperly formed bushes;
Untimely removal of weeds;
Greenhouse temperature below 18-16℃;
Greenhouse temperature above 28-30℃;
contaminated soil;
infected seeds;
dirty tools and shoes;
bushes are not rejuvenated, dry and yellowed leaves of cucumbers, spoiled and overripe fruits, fruit-bearing branches are not cut off;
too abundant or unstable watering;
watering with cold water (below 20-22℃);
too much nitrogen-rich top dressing;
insufficient fertilizing;
allowing fruit to soil contact;
careless picking of cucumbers, allowing mechanical damage to plants and fruits.

Autumn Events

After the end of the season, all plant residues, together with the roots, are removed from the greenhouse and burned. It is in them that the main part of fungi hibernates.

Greenhouse growing conditions complicate crop rotation. Usually the structure is built for the cultivation of one crop. Therefore, every year it is necessary to completely replace the fertile soil layer. The soil quickly accumulates fungal diseases and pests.

Some vegetable growers practice soil treatment with fungicides, insecticides. Even with this method, it is necessary to remove the top layer of soil 5-6 cm, in which the main amount of pests and fungi accumulate. Thermal treatment of soil with steam has proven itself well.

All parts of the structure and tools must be treated with an antiseptic, for example, bleach (400 g per 10 liters of water).

White rot

Sclerotinia fungus, also called white rot, affects many cultivated plants, including the gourd family.

Most often, outbreaks of fungal diseases of cucumbers in the greenhouse occur in early spring and autumn, when it is most difficult to achieve normal temperature and humidity conditions.

The optimum temperature for the development of sclerotinia is 12-16℃.The foci of white rot are usually located on the forks of the stem and in the basal part. Any place with mechanical damage is especially vulnerable. With dense plantings, white rot quickly spreads in the garden between plants.

Focuses of infection first take on a rotten weeping appearance, and then they are covered with a white cotton coating. This is the growth of sclerotinia mycelium, which gradually falls off and hardens. Solid rounded inclusions - sclerotia - are formed inside. The plant part in this place becomes soft, slimy. The stem is crushed and broken, the affected fruits become flabby.

Treatment

The treatment of white rot on cucumbers in the greenhouse is:

removing deeply affected bush branches;
cutting and cleaning with a knife of shallow pockets of decay;
treatment of superficially affected and cleaned parts of the stem with a mixture of chalk and copper sulfate (1:1)
treatment of all bushes with fungicides: copper chloride (2.4 kg/ha), foundationazole (0.8-1.0 kg/ha), Bordeaux liquid (1%).

If you do not get rid of the infected parts of the bushes at the beginning of the development of the disease, the fungus will kill the entire plant and begin to spread microscopic pieces of mycelium through the air. Tools, gloves and clothing after contact with infected cucumbers should be washed with soap and treated with fungicides.

Tip!

Removed bushes should be burned immediately outside the site, as white rot can affect most cultivated plants.

If the disease is detected at an early stage of development, you can try to treat the affected areas with a mixture of chalk and copper sulfate.

The following control measures must also be taken:

treat all cucumbers in the greenhouse with fungicides;
reduce watering to a minimum for 10-14 days;
ventilate greenhouses twice a day;
feed cucumbers with potash-phosphorus fertilizers;
achieve an increase in temperature to 25-26 ℃.

Grey Rot

Another type of fungus called Cucumber Gray Rot (Botrytis cinerea) is also a frequent unwanted guest in greenhouses. Most often, foci of infection occur at the site of mechanical injuries. The ovary becomes infected through the pistillate scar.

High humidity (above 90%) at temperatures of 15-16 ℃ are optimal for the development of gray mold. The initial source of infection is usually untreated greenhouse structures, infected soil and uncleaned plant debris.

Signs of the onset of the disease are wet loose spots, which eventually become covered with a fluffy coating of gray. The plant part under the fungus quickly softens and rots.

Control Methods:

cessation of foliar feeding;
reducing humidity in the greenhouse;
removal of infected bushes and fruits;
treatment with fungicides ("Euparen multi", "Trichodermin")

Fusarial root rot

If in the middle of the growing season the plant suddenly stopped developing, began to wither, throw off flowers and ovary, most likely the cause was the defeat of the roots by Fusarium. A brown rot appears at the base of the stem.Under it, the plant part softens to a mushy state. As a result of decay, the root part becomes loose and quickly dies. The main control measures are the removal of diseased bushes along with the underground part. The resulting well is watered with a solution of copper sulfate.

You can try to root strong stems again by cutting off the diseased root and treating the end with a growth stimulator.

Provoke the development of the fungus:

watering with cold water;
overwatering;
overabundance of mineral fertilizers.

The fungus lives in the soil for a relatively short time, therefore, in open ground with proper crop rotation, this disease practically does not occur. But in greenhouses, with the annual cultivation of one crop, an acute question may arise, what to do with the constant infection of plants with Fusarium.The main method of combating the disease is the complete replacement of the soil.

Phytophthora root rot

The disease usually suddenly affects developed bushes ready for fruiting. The plant quickly and irreversibly fades, as the roots rot. Provokes a disease of stagnant moisture in the soil. The roots become covered with black watery rot, which can be seen at the base of the stem.

Since it makes no sense to fight the disease of already affected bushes, measures are usually taken to prevent it:

preparing high beds for planting cucumbers to improve drainage;
avoid topsoil compaction by loosening and mulching;
exclude long, frequent watering and high temperatures.

Fungal and bacterial fruit rot

Fruit damage by fungal and bacterial rot in the greenhouse can occur for many reasons:

inaccurate shaping and tying to the trellises, allowing the contact of cucumbers with the soil;
mechanical damage to fruits;
secondary infection of fruits with bacteria and fungi, after violation of the integrity of cucumbers due to other diseases.

Most often, the focus of the disease is located on top of the cucumber at the point of attachment of the flower.

Fruit Blossom Rot

Sometimes the fruit tops start to darken and take on a rough, leathery appearance. Gradually, the tips of the cucumbers turn black and rot. Such a physiological disorder is called vertex rot and there can be several reasons for it:

damage to the root system;
unstable watering;
lack of calcium in plant nutrition;
excess nitrogen.

If the tips of cucumbers rot in the greenhouse, you need:

mulch the soil, which will help avoid sudden changes in soil moisture;
carry out mineral plant nutrition with a high content of calcium and minimal nitrogen;
establish stable watering.