Every gardener who has decided to plant greenhouse cucumbers hopes for large shoots of an environmentally friendly product, but unfortunately, expectations do not always live up to reality. The question: “why do cucumber leaves have holes, spots or mold” worries every novice gardener. To understand this, it is worth studying in more detail various fungal cucumber diseases and methods of their treatment.
The greenhouse may meet all the necessary requirements, watering is done in a timely manner and in the right quantity, the percentage of seed germination corresponds to the norm, but the results still leave much to be desired. The greenhouse creates optimal conditions for the germination of not only garden crops, but also harmful microorganisms, bacterial flora and pests that expose plants to various diseases.
Phytodiseases are the main problem when growing greenhouse cucumbers. All kinds of infections cause maximum damage to cucumbers. In greenhouse conditions there are approximately twenty species.
A greenhouse is an ideal environment for the development of pathogenic microflora and therefore it is important to know how to quickly and effectively eliminate the disease, without harm to the plants.
The appearance of spots and holes on the leaves of seedlings
At the beginning of spring, gardeners transfer cucumber seedlings to greenhouse conditions and care for them with increased attention. Important: Seedlings of cucumber plants should be placed deep in the soil. Under favorable external temperature conditions and sunny weather, the crop begins to grow at an accelerated pace. However, cucumbers may develop small spots or holes. Round holes are considered the most dangerous because they are the result of parasitic fungi.
In industrial production, agronomists can accurately determine the type of disease by the appearance of holey leaves and prescribe the necessary drugs for treatment. However, in garden conditions it is not possible to carry out laboratory testing of a perforated sheet, so a different approach is used.
The point is not to miss the moment when the disease has not yet reached the terminal stage (a small number of spots) and immediately move on to actively combating the disease using folk remedies.
It is quite effective to spray a mixture of ash and lime on the leaves. This treatment will neutralize fungal microflora.
This effective remedy will help with the initial stage of the disease. If there are a large number of holes on the leaf blade, leaves with small holes should be removed in order to avoid the subsequent spread of the disease.
How to plant cucumbers
Sowing of cucumbers begins on the twentieth of May, regardless of the place of sowing. This crop from the pumpkin family develops well in warm conditions, but requires increased attention. A gardener with many years of experience can immediately identify any problems that have arisen. But what should novice gardeners do?
As practice shows, on the first sunny days, gardeners sow cucumbers for the first time, and then are surprised at the large percentage of dissimilarity of the seeds. The reason lies in the night temperature. Crops made in early spring are covered with holes.
It is necessary to take measurements of the soil temperature, as well as create a reliable shelter for the plant. If you want to get early fruits, you should plant the crop in separate containers so as not to disturb the root system during transplantation. Plants with damaged roots do not take root for a long time, they often get sick or even die.
Causes of defects on plant leaves
The appearance of spots and holes on the leaves is the most common problem with greenhouse cucumbers. The reason lies in the following: due to closed conditions and high humidity, dew forms in the greenhouse, as a result, the leaves of the cucumbers become covered with dew.During the daytime, a lens effect is created in the drop and the sun's rays burn the plant (this is how holes are formed).
Powdery mildew and downy mildew
Often, fungal diseases develop due to increased spores on the leaves of the plant. If a plaque appears on the cucumber in the form of small round spots, a number of measures are taken to treat powdery mildew. When the first holes appear on a plant leaf, they are dusted with ash and germinate. Powdery mildew is treated with a weak solution of colloidal sulfur or mullein in a proportion of 40 grams per 10 liters of water. This is the most effective remedy for treating plants with holey leaves.
Important: in advanced cases, experts recommend using HOMom.
At low night temperatures, holes may appear on the leaves of cucumbers; any gardener should know what to do in such cases. At the same time, the number of spots is constantly growing, and they change their color to dark brown. After this, a gray coating forms on the underside of the leaf and the plant dies. This disease is called downy mildew or downy mildew. To treat downy mildew, it is worth reducing watering and fertilizing the plant, ventilating the greenhouse and treating the leaves with a special milk solution.
Olive spot
Olive spot is a disease caused by parasitic fungi. The main symptom of this disease is the appearance of brown-yellow spots on the leaves, while watery dark spots appear on the fruits and curvature of the fruit occurs.
If the above signs appear on cucumbers, then you should immediately begin treatment for olive spot.Cucumber leaves should be treated for olive spot by regularly airing and removing leaves in holes.
Gray rot
This disease often appears in mid-July. Its main symptom is the appearance of mucus on the stems and petioles of leaves.
The method of dealing with gray mold is quite simple:
- It is necessary to prepare a special mixture consisting of chalk and potassium permanganate diluted in water;
- Clean the affected area from accumulated mucus;
- Treat the affected area with the mixture.
Causes of disease development
Cucumbers are more susceptible to diseases on loamy and podzolic soils. Temperature also plays an important role. The range should be between 14 and 28 degrees Celsius. Deviations in one direction or another have negative consequences for the germination of greenhouse cucumbers. In turn, watering should be uniform, and the water for irrigation should not be too cold.
How to deal with holes
Industrial agricultural complexes use various chemicals and special steaming technology as methods of combating diseases. However, these methods are not possible in garden conditions.
Advice from an experienced gardener: the number of infected plants in a greenhouse is significantly reduced with regular ventilation. It is just a myth that tropical plants require a special atmosphere and do not tolerate drafts.
For plants, the only danger is the draft that enters the bathhouse atmosphere. Bath air should not be allowed to form in the greenhouse. Let there be a light sunny breeze in the greenhouse. The sooner you ventilate the greenhouse, the better: this will save the plants from the effect of drafts and the appearance of fungi and rot.
First of all, it is necessary to open the upper doors of the greenhouse, then the doors, so that ventilation occurs more evenly (from top to bottom). It is most effective to carry out this procedure in the morning, when the air is saturated with energy and freshness. The morning sun has always been considered the most effective helper of the harvest. In the morning at 7-8 o'clock the bees are already working with all their might.
That is why this is the best time to treat leaves with holes in plants and grow seedlings. If you take care of the plant later, there is a high probability that the cucumbers will become infected with various fungal diseases and the harvest will be small.
Preventive methods of control
Every day, early in the morning, it is necessary to inspect the greenhouses, check cucumber plants, treat wounds, and remove mustaches. It is recommended to treat all damage (holes and spots on a cucumber leaf) with a mixture of water, chalk and potassium permanganate.
When does a cucumber sprout fastest? In the evening, when solar activity decreases, the greenhouse should be packed and all doors and window openings tightly closed. Thus, warm air remains in the greenhouse throughout the night (this is the optimal time for cucumber germination).
At the end of August, the length of night time increases and the temperature decreases. That is why increased attention and care of plants is necessary at this time, since it is during this period that rot and various fungal diseases can appear.
