Why gray rot appears on cucumbers and how to deal with it

cucumbers very often exposed to diseases such as gray rot. If you find light brown spots on your plantings, you should be wary - perhaps this is rot. In this article we will figure out what this disease is, why it can occur and how to treat it.

What kind of disease is this

Gray rot of cucumber is a bacterial and fungal disease. The causative agent is the fungus Botrytis cinerea. It affects a large number of garden crops. Carried by insects, air currents, birds and gardening tools.

The fungus can enter the plant through wounds from mechanical damage or through the stigma of a flower's pistil. In the second case, the flowers quickly die and the entire harvest is lost.

The first signs of infection are the appearance of slippery light brown spots on the stem or leaves.. They have a loose structure and over time become covered with a gray fluffy coating. Under the affected areas, the plant rots and gradually dies.

The photo shows a cucumber with gray rot.

The fungus is able to survive winter in the soil or on a greenhouse frame in the form of sclerotia.

How dangerous is the disease?

After infection, the fungus begins to germinate, increasing its mycelium more and more. At the same time, toxic enzymes are produced that spread throughout the plant. Neighboring healthy tissues also begin to become stained and rot.

If the stem is affected, the flow of water through the vessels is disrupted, and the cucumber experiences an acute lack of nutrients and moisture.

Gray rot causes cucumbers to significantly reduce their yield. With severe damage, the plant dies completely.

Causes of gray rot on cucumbers

The main factors of infection can be both favorable natural conditions for the development and reproduction of fungi, and agrotechnical mistakes of the gardeners themselves.

Here is a list of possible reasons:

1. High air humidity (90%).
2. The ideal temperature for the development of the fungus is 16-17 degrees.
3. Sudden temperature changes.
4. Strong drafts.
5. Lack of ventilation in the greenhouse.
6. Planting density.
7. Watering with cold water.
8. Lack of fertilizers.
9. Excessive application of nitrogen-containing fertilizers.
10. Failure to comply with crop rotation.
11. Mechanical, chemical and thermal damage to plant tissue.
12. Using untreated seeds. Lack of regular weeding and cleaning in the greenhouse.
13. Lack of disinfection of the soil and internal surface of the greenhouse.
14. Loss of turgor (water pressure).

When the microclimate in the greenhouse improves, the development of the disease stops. To do this, it is enough to establish ventilation, increase the temperature to 25 degrees and reduce the humidity to 80%.

However, it will not be possible to get rid of the fungus using such measures. An integrated approach is needed.

In open ground, natural climatic conditions are dangerous. Frosts, sudden temperature changes, cold rains and even animals - all this contributes to the general weakening of the plant and its infection.

Read also:

How to deal with blossom end rot of tomatoes in a greenhouse.

Why is the Marble pumpkin so popular among farmers?

What to do if white spots appear on the leaves of tomatoes in the greenhouse.

How to fight

When the first signs of the disease are detected, it is necessary to stop watering and fertilizing, ventilate the greenhouse and carefully inspect all cucumbers.

Diseased leaves should be removed, and severely affected plants should be torn out and burned. This is necessary to prevent the fungus from spreading to other crops.

Then you can use various methods at your discretion.

Agrotechnical techniques

Seedlings with signs of gray rot are usually immediately destroyed. Of course, I want to save adult plants. To do this, make healthy pruning: the lower leaves are cut off and laid on the ground, sprinkled with soil with Trichodermin on top.

It is also very useful to add peat, ash, chalk or sawdust to the top layer of soil around infected cucumbers. They need to be brought in to a depth of 4-5 centimeters. You just need to do this carefully so as not to damage the root collar.

Ready-made drugs

Modern means of combating diseases are very effective and can destroy the fungus quite quickly. But chemicals can also cause some harm: disrupt the soil microflora, burn the plant, etc. Therefore, you must strictly follow the instructions on the packaging.

Proven chemicals:

1. "Hom" is copper oxychloride.
2. "Rovral" - contains 50% iprodione.
3. "Euparen multi" is a moderately toxic fungicide.
4. Tetramethylthiuram disulfide.

Biological drugs:

1. "Koniotirine."
2. "Trichocin."
3. "Trichodermin."
4. "Glyocladin."

Note. Biological drugs should be stored in a cool place, otherwise they may lose their medicinal properties. They contain beneficial fungi that penetrate the mycelium of harmful formations and destroy it.

Traditional methods

Folk remedies are less effective, but safer.They are suitable for the initial stage of the disease. To treat severely affected cucumbers, it is better to choose store-bought preparations. Before using any of the products, you must add 40 g of laundry soap to it for better preservation on the surface of the plant.

Here is a list of the most effective compounds:

1. 10 ml of greenery, 10 liters of water.
2. 1.5 g of potassium permanganate, 10 liters of water.
3. 10 g of boric acid, 30 drops of iodine, 1.5 g of potassium permanganate, 10 liters of water.
4. 1 liter of milk, 30 drops of iodine, 10 liters of water.
5. 50 g of soda ash, 80 g of copper sulfate, 10 liters of water.
6. 5 liters of whey, 5 liters of water.
7. Pour 300 g of wood ash into 3.5 liters of water and boil for 15 minutes. Add water to a volume of 10 liters, let it brew for 4 hours, filter.

Folk remedies should be used 4-5 times every 5-7 days.

Processing rules

It is very convenient to use a pump sprayer for processing cucumbers. It allows you to spray the solution evenly and control its quantity. It is advisable to use protective gloves and a respiratory mask. Clothes must be closed.

It is better to carry out treatment early in the morning or in the evening (before dew falls and after it subsides). It is important that the solution remains on the surface of the plant for at least 2 hours. For this purpose, choose a dry and windless day.

Spray the cucumbers from bottom to top at a distance of 15 cm. The soil should also be sprayed.

Preventive measures

Measures to prevent the appearance of gray rot are quite simple. Here are the main preventative measures:

1. Watering with warm water.
2. Regular weed removal.
3. Removing diseased leaves and empty flowers.
4. Burning of plant residues.
5. Avoid contact of fruits with soil.
6. Regular ventilation.
7. Maintaining a constant temperature regime.
8. Spraying with growth stimulants.
9. Changing the planting site in open ground.
10. Replacing soil in a greenhouse.
11. Disinfection of seeds before planting.

Useful tips from experienced summer residents

Experienced gardeners recommend carrying out all preventive treatments in spring or summer. Since the sclerotia of the fungus can remain in the soil in winter, they are viable again in the spring. Protection of plantings at this time is simply necessary.

It is also recommended to process not only cucumbers, but also other crops growing in the neighborhood.

All gardeners agree that the best prevention is keeping the greenhouse clean, regular watering and proper care.

Conclusion

The health of the plantings depends entirely on the gardener. You can protect them even from unfavorable climatic conditions: cover them in time from cold rain outside or thin out the beds and ventilate the greenhouse.

The best way to protect cucumbers from gray rot is prevention. A strong and healthy plant is less susceptible to any diseases than a damaged and wilted one.