Disease control of cucumbers in the greenhouse

disease control of cucumbers in the greenhouse Blog

If you want to increase the yield of cucumbers, then you need to learn how to notice diseases at the very initial stage and understand what means are available to eliminate them. Early detection will help to eliminate problems in time.

Powdery mildew problems

In this case, white (or in some cases red) spots appear on the leaves and on sections of the stem, resembling flour. After some time, this raid captures the entire leaf. Then the plant turns yellow and dries up. This disease belongs to the category of fungi and leads to the cessation of the appearance of fruits.

Powdery mildew on cucumber leaves
Powdery mildew on cucumber leaves

The cause is pathogens that spread in cold and rainy weather. But, as soon as the temperature rises to + 20 ° C, the problem stops developing. Most often, this problem clings to those plants that have received too much nitrogen fertilizer. As well as those that receive too little moisture or are watered without a specific schedule.

To prevent the appearance of powdery mildew, you need:

  • alternate planting sites for cucumbers (do not sow for several years in a row in one area). A pause of 4 years should be maintained;
  • timely clean the beds from cucumbers and other residues from plants;
  • as soon as the harvest is harvested, disinfect the room (with a formalin solution, for example);
  • increase the temperature to + 25 ° C (close the room at night or wrap the plants with a film);
  • do watering with warm water;
  • create or use hybrids that have resistance to the problem.

At the first signs, you need to spray the plant with a fungicide (topsin) or use a TOPAZ solution (2 ml per 10 liters of warm water). Spray when there is no wind. A solution of copper oxychloride also helps (40 grams per 10 liters of water).

Folk methods also work well:

  • mullein infusion (1 kg per 3 liters of water). It is infused for 3 days, filtered and mixed again with 3 liters of already purified water;
  • 1 liter of sour milk to 1 liter of water. Spraying takes place once a week.

Downy mildew problems (problems with downy mildew)

A lot of small yellow spots form on the leaves. Then they increase and lead to the drying of the entire sheet. The reason is a fungus that develops with increased humidity. Also, the problem appears if you water only with cool water.

Downy mildew - downy mildew
Downy mildew – downy mildew

To prevent it, you need to harvest on time, follow the rules for planting and alternating places (4 years) and do not use cold watering.

As soon as spots appear, you need to immediately stop watering and stop feeding. For processing use:

  • warm solution of polycarbacin (+25°C);
  • copper oxychloride (Bordeaux liquid – in 10 liters, dilute 100 grams of freshly slaked lime and copper sulfate).

After the procedure, you need to make sure that the temperature does not fall below + 25 ° C and cover the plants with a film.

Problems with cladosporiosis

Round brown or greenish ulcers appear on fruits and stems. After three days, they begin to darken and increase. And on the leaves they dry out and turn into holes.

The problem appears when the temperature drops or during frequent rainy weather. Tends to spread to other fruits and also remain in the soil.

To prevent a problem from arising, you need to regularly ventilate the room, remove plant residues, and also do not use cold watering and do not give access to rain.

Cladosporiosis of cucumbers
Cladosporiosis of cucumbers

At the first sign you need:

  1. stop the water supply for 5 days;
  2. increase the temperature in the room (close windows and doors at night and cover the fruits with foil);
  3. use Bordeaux liquid (1% solution), copper oxychloride (0.4%).

White rot (sclerotinia)

A white foreign substance is formed on the plant. Over time, it darkens, approaching black. Soon the whole plant, including the fruits, is covered with bloom, mucus and rots. The reason is a fungus – sclerocinia, wintering in the soil and passing to the plant as soon as too much moisture accumulates in the ground.

White rot (sclerotinia)
White rot (sclerotinia)

If formations appear on the plant, you need to cut them out until you reach healthy tissues. Cuts should be treated with lime or crushed charcoal. If the problem has captured too much area, then remove the completely infected part or the entire plant. At the end, dilute urea (10 g), zinc sulfate (1 g) and copper sulfate (1 g) in 10 liters of warm water.

Problems with gray mold

On the leaves, stems and flowers appear brown blurry spots with a gray coating. This is a bacterial disease and it captures all parts of the plant.

At the first stages, use a fungicide for processing (Rovral or Bayleton paste). All infected areas must be removed.

Root rot problem

The leaves begin to fade rapidly and finally dry up. And the roots themselves become rotten and have a red color. This is the most dangerous and common disease. The disease develops under unfavorable conditions during growth and fruiting (too high temperature and excessive watering).

At the first sign, you need to make sure that new roots begin to form. To do this, add another 5 cm of new soil around the plant. This will cause the plant to grow new roots. Or you can remove the leaves on the lower part of the stem and place them in the soil of fertile soil. A week later, new roots should appear. During this time, use warm water for irrigation and do not run it under the root.

If the plant is already dry, then it must be dug up and discarded. Moreover, you need to pull out along with the soil, and put new soil in the hole. After finishing work, clean the tools in soapy water.

Copperhead problems (anthracnose)

Dark brown spots form, the leaves dry, and wet ulcers are found on the fruits. The cause in most cases is already infected seeds obtained from diseased plants. In addition, the cause is cold watering and frequent temperature changes.


To fix use:

  • Bordeaux mixture (1%). Treat once a week before harvest;
  • copper sulfate (0.5%). Treat the affected areas and then sprinkle them with lime or use charcoal.

Cause of yellowness on the leaves

Most often, the problem is a sharp temperature drop (change of day and night) or the absence (insufficient amount) of potassium. To eliminate the first reason, you only need to provide heat (film and closing the room for the night).

To solve the second, use:

  • infusion of ash (within 2 days, 3 tablespoons are infused in 1 liter of warm water);
  • onion infusion (2 tablespoons of onion peel boiled in 10 liters of water).
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