White spots and white coating on cucumber leaves: why the disease appears and what to do

Cucumbers are a very delicate crop and require special attention. Pathological changes can often appear on the leaves: they are the litmus test for all cucumber “illnesses”. Any manifestations of diseases, lack of nutrients or “enemy invasion” of pests will immediately affect the appearance of the plates. Often light, almost white spots or a coating of the same color appear on the leaves. This means that all is not well with the plants. We'll tell you what to do when white leaves appear on cucumbers.

Why spots appear 2. Violation of agricultural cultivation practices 2.1. Incorrect temperature 2.2. Lack of light 2.3. Incorrect air humidity 2.4. Improper watering 2.5. Untimely planting 2. Lack of nutrition 3. Diseases and pests 4. Incorrect soil 5. Natural aging

Photo by G. Kuzmitskaya: If you encounter a problem, you need to identify its cause.

Why do white spots appear on cucumber leaves?

Let's look at what can cause “white” problems.

1. Violation of agricultural cultivation techniques (light, heat, humidity) and care rules.
2. Unbalanced diet.
3. Manifestation of the effects of pests and diseases.
4. Inappropriate soil.
5. Aging.

I'll tell you about each reason in more detail.

Photo by pixabay/Alexei_other: There are five groups of reasons why plates change color.

Prevention

Plaque that appears due to powdery mildew must be treated comprehensively. First of all, you need to plant only strong and resistant varieties of cucumbers; at the first signs of infection, leaves with plaque should be torn off, you can spray them with mullein, and increase fertilizing with potassium. If cucumbers in a greenhouse are infected with white rot, the affected areas must be removed immediately. Treat the cut areas with charcoal; if the bush is completely affected by the fungus, then it is necessary to remove it without sparing. To prevent infection of the remaining fruits, you need to water them with a solution of copper sulfate. To overcome downy mildew, it is necessary to replace or disinfect the soil. At the first sign of damage, remove leaves and stems. If cucumbers grow in a greenhouse, then treatment should begin with complete disinfection, best done in the fall. You can use copper sulfate or pour boiling water over the soil and cover with foil. It is necessary to disinfect not only the soil, but also all garden tools. Dead plants must be removed and burned outside the garden to avoid infecting others. In stores for gardening and gardening there is a sufficient range of chemicals to combat fungus, these are “Hom”, “Topaz”, solutions of copper, mullein, colloidal sulfur. There is a good remedy for treating white rot - weekly spraying of the bushes with a solution of soda and soap. In order to get a good harvest, you cannot do without proper care of cucumber bushes. You should inspect the bushes; if the leaves begin to turn yellow or acquire a white tint, or spots or plaque appear on the stems, then treatment should be started as soon as possible. You should inspect the bushes; if the leaves begin to turn yellow or acquire a white tint, or spots or plaque appear on the stems, then treatment should be started as soon as possible. In all cases, to prevent damage to cucumbers by any fungi, it is necessary to plant only hybrids that are resistant to pests and diseases. The bushes should not be close and densely located to each other. It is necessary to regularly weed the beds and provide the cucumbers with sufficient ventilation. It is necessary to maintain the correct temperature in the greenhouse and not allow it to drop below +23°C. Water cucumbers only with warm water, avoid drafts and temperature changes. Cucumbers need to be planted in a different place every year due to the fact that possible pathogens remain in the soil for a long time.

What to do if white spots appear on cucumber leaves due to growing errors

If there is a prolonged period of insufficient heat, light or improper humidity, white spots may appear on the leaves. The lower leaves begin to turn white first. The impact of each factor occurs in its own way:

Unfavorable thermal resources

Cucumber is a light- and heat-loving plant. Cultivation of the crop requires elevated temperatures (+20…+25 degrees). But the bushes do not tolerate elevated temperatures, above 35 degrees, especially for a long time.

Lack of sunlight

More often this problem concerns greenhouse cultivation. Cucumber vines are usually very densely leafed, so only the upper tier of leaves gets enough light. But if the site is not planned correctly, the problem can also appear in open areas.

What to do:

1. For cucumber beds, you should choose well-lit areas, avoiding overly shaded ones.
2. Greenhouse structures should be kept away from tall trees and abundantly growing shrubs, the crowns of which may prevent good access to light for greenhouse inhabitants.
3. Try installing additional lighting.
4. Follow planting rules taking into account the plants' requirements for nutritional area, avoiding thickening.

Photo pixabay/Alexei_other: Due to improper care, the plates turn white.

Incorrect air humidity

An air humidity of 70–80% is favorable for the crop. In open areas, these values ​​are regulated by the wind. If white leaves appear on cucumbers in a greenhouse, regular ventilation will help - in case of excess humidity. If the air is too dry, adjust the watering.

Improper watering of cucumbers

Both under-watering and over-watering can cause white leaves to appear. Once the color changes, they may subsequently dry out. It is not difficult to correct the situation. You just need to adjust the timing and frequency of watering, as well as the temperature of the irrigation water.

If the color of only the lower leaves has changed and then the process of whitening of the above-ground mass has stopped, then there is no need to worry. This is probably a temporary phenomenon. Try the above tips. If you have correctly identified the cause of the disease, then these measures should help correct the situation. If the result is negative, you should look for the cause of the whitening of the leaves elsewhere.

Incorrect time for planting cucumbers

Cucumbers are sensitive to planting conditions. Planting too early can cause whiteness. You should adhere to the recommended planting dates depending on the region. If exposed to low temperatures, young plants may die. The first sign may be the appearance of a whitish color of the leaf apparatus.

Photo pixabay/Alexei_other: Urgent measures need to be taken to return the green leaves.

Conditions in the greenhouse for the growth of cucumbers

The advantages of growing cucumbers in a greenhouse are obvious: under a protective film, the heat-loving and very tender plant, especially in the early stages of development, is not afraid of sudden temperature changes and sudden cold snaps, so characteristic of changeable spring weather.

However, not all gardeners know that the technology for caring for cucumbers growing in a greenhouse has features compared to growing this crop in open ground.

These features boil down to the following rules:

1. Lighting. When planting seedlings early, the cucumber bed should be additionally illuminated, since there is not enough natural light during this period for the development of the bush and the establishment of greenery. To illuminate every 10 m² it is necessary to install one 600 W lamp. If the greenhouse area is less than 7 m², one 400 W lamp is sufficient. If there is not enough light in the greenhouse, it is necessary to regulate the temperature towards lowering it. In this case, the cucumbers will develop more slowly, but their immunity as a whole will not be affected.
2. Temperature conditions. Directly depends on the phase of vegetative development of the crop. So, at the stage of planting seeds, the soil should be warmed up by at least +24°C, the air - by about three degrees more, and there should be no differences between day and night temperatures. After the emergence of seedlings, the air and soil temperatures should be approximately the same, at +24°C, then after 5–6 days this figure decreases by a couple of degrees. After planting in a permanent place, the air and soil temperature (taking into account daily fluctuations) should be +19...+21°C.
3. Watering. In winter, the procedure is carried out in the morning on the brightest days. In the warm season, the frequency of watering is approximately once every 2–4 days, depending on the light intensity. The water should always be warm.
4. Soil care. To prevent the development of fungal diseases of the root system, the soil in the garden bed should be carefully loosened after each watering (trying not to damage the surface roots of the cucumbers) or mulching technology should be used.
5. Air humidity. At the stage of emergence of seedlings, this figure should be 90–95%, however, after the formation of the first real leaf, the humidity decreases, but not by more than 10%, otherwise the leaves become deformed and dry out.
6. Ventilation. When growing in open ground, problems with air stagnation in the garden bed cannot arise, however, when covering cucumbers with film, inexperienced farmers often forget about the need to regularly ventilate the greenhouse, which is why the plants get sick.
7. Feeding. The recommended fertilization scheme for greenhouse cucumbers involves carrying out this procedure five times during the season using organic matter (chicken manure or mullein), as well as complex mineral fertilizers.

What to do if cucumber leaves turn white due to nutritional deficiency

It rarely causes white leaves to appear.

• Typically, whiteness of the lower leaves, which then spreads upward throughout the plant, appears due to a deficiency of magnesium or potassium.
• When dark veins appear on a whitish background, there is a lack of manganese and iron.
• With a lack of copper in the diet, the upper leaves suffer, and later the lower ones.

The solution is obvious - provide nutritional supplements with the necessary elements. It is better to use complex fertilizers containing a full range of microelements, which you should read about on fertilizer packages. The lack of potassium and manganese can also be compensated for by adding simple means: ash solutions, watering with a weak solution of potassium permanganate.

Photo by G. Kuzmitskaya: It is necessary to add fertilizer to help the plants.

Symptoms of the disease

Initially, the disease manifests itself by the appearance of weeping sores at the base of the stem. The fungus then spreads upward. Spots appear on the leaves in the form of a flaky coating, reminiscent of cotton wool. A little later, mucus forms on the affected areas, and then black dots appear, which are formed sclerotia.

Hay will help against powdery mildew on cucumbers: how to use it to combat the scourge

The infection gradually covers all tiers of the bush. Affected:

• stems;
• petioles;
• leaves;
• fruit.

The mycelium can develop hidden inside tissues. In this case, only mucus will appear on the surface of the diseased plant.

If symptoms are detected, you must immediately stop watering and fertilizing. Treatment includes treating plants with compounds to which the pathogenic fungus is sensitive.

How to treat white leaves on cucumbers affected by pests and diseases

If you think that you fully comply with all agrotechnical cultivation requirements, then there is a high probability that your cucumber plantings are infected with diseases or infested with pests.

Pest Control

Spider mites are most often found on plants. Appears when the temperature is too high and the weather is dry. On the underside of the plates (later on the stems and ovaries) small white spots and a barely noticeable thin cobweb appear. Plant development slows down. The white edges on cucumber leaves curl and dry out over time. Recommended control measures are preventative.

1. If a pest was present last season, the entire greenhouse should be treated in advance in the spring with Fitoverm, Akarin, Anti-mite and others. Autumn disinfection of the greenhouse will significantly increase the chances of complete destruction of the pest before it leaves for the winter.
2. Do not leave plant debris or weeds inside.
3. Carefully inspect the appearance of plants for the presence of pests.
4. To treat a spotted tick, special insectoacaricide preparations “Bitoxibacillin”, “Karbofos” and others are used. Regular insecticides will not help. Unfortunately, chemicals are not harmless to humans.

Folk remedies:

• treatment with an aqueous solution of laundry soap,
• planting nearby herbs that attract ladybugs - natural enemies of ticks,
• sow dill nearby to repel the pest.

The required temperature in greenhouses should be regularly maintained, avoiding prolonged overheating.

Photo by ru.depositphotos: Defeat pests to save plants.

Disease Control

Illnesses often cause the problem.

• Anthracnose. It affects plants both in greenhouses and in open beds. It manifests itself in the formation of white or yellow spots, which eventually merge into one large spot. During fruiting, brown spots appear on the fruits.
• Ascochytaosis. Causes leaf tips to turn white. In the most difficult cases, the plates become completely white.
• White mosaic. Viral disease. White spots with a yellowish tint appear on the surface of the mass. The growth of the vines slows down, and ugly fruits appear. The disease occurs primarily during sudden temperature changes or during a long hot period with temperatures above +25 degrees. The virus is transmitted from other infected plants through tools, people when caring for plants, and insects.

• Powdery mildew. The fungus first appears as a white coating on the edges of cucumber leaves, then moves to the central part of the plate on the ovaries, roots and stems. Reasons for the development of powdery mildew: excess nitrogen fertilizers, unregulated watering.

Photo by ru.depositphotos: Cucumber mosaic.

To combat diseases, preventive measures and control measures are recommended:

1. Destruction of plant residues.
2. Preparation of seed material before sowing.
3. It is necessary to protect your plantings from the appearance of spider mites, which, through their activities, weaken plants, reduce their immunity, and provoke diseases.
4. Prepare the soil correctly: disinfection before sowing seedlings, spilling with a solution of potassium permanganate, “Fitosporin”.
5. Plants are sprayed with Bordeaux mixture (1%), copper sulfate (3 g x 5 l of water), urea solution: 5 g x 5 l of water.
6. The use of fungicides, primarily of natural origin: “Fitosporin”, “Alirin” or their analogues. Recently, many good fungicides have appeared on the market that help with the appearance of white leaves: “Quadris”, “Kuproksat”, “Jet”. Use only as directed.
7. Care for your plants properly.
8. Grow resistant varieties.

Ascochyta blight of cucumbers

One of the most dangerous diseases of cucumbers, attacking both seedlings and adult plants. It also affects watermelon, melon and pumpkin. Moreover, plants in greenhouses and open ground get sick with equal success. Weak plants die quickly. A classic example of when it is easier to prevent a disease than to treat it later.

Light gray spots form along the edges of the leaves, gradually spreading over the entire leaf area. Black spots appear on them - fungal bodies with spores. Small whitish-brown spots form on the stem, shoots and root collar. In case of secondary bacterial infection, gum (exudate) is released. The fruits turn black and mummify or become covered with a dense network of black dots.

Cucumber varieties resistant to ascochyta blight: Amazonka, Luzhok F1, Romans F1, Izobilny, Flodovity, Leningradsky Greenhouse.

Cucumber leaves turn white due to improper soil

The optimal acidity for cucumbers is about 7 pH. Soils with lower values, e.g. more acidic, very harmful to the crop. Nutrients are less easily absorbed, which is why the leaves turn white. When preparing the soil before planting seedlings or sowing, any deoxidizers should be added to determine the acidity of the soil. You can water the holes before planting seedlings with a solution: dilute 500 g of ash in a bucket of water.

Photo by G. Kuzmitskaya: If the cause of the disease is in the soil, you need to add ash.

Bacteriosis of cucumbers

The full name of this disease is: “angular leaf spot of cucumber .” It affects any pumpkin plant, causing the leaves to die. Bacteriosis spreads in warm and humid environments. Frequent and heavy rains, followed by heat, cause bacterial activity with subsequent death of 50-70% of the crop. Necrotic spots are the last stage of development of bacteriosis, after which the plant can no longer be saved.

Bacteriosis manifests itself on any parts of plants (cotyledons, leaves, flowers, fruits). The main symptom is the formation of brown oily spots. Their number gradually increases from 1 to 50. In dry weather, the spots become crusty and fall off along with part of the leaf. At the end, only veins remain from the leaves.

Cucumber varieties resistant to bacteriosis: Vyaznikovsky 37, Izyashchny, Konkurent, Nezhensky 12, Dalnevostochny 6, Dalnevostochny 12.

Natural aging of plants

Towards the end of the growing season, photosynthesis processes slow down, the plant gradually turns white and withers. Folk methods of struggle are used both for treatment and as prevention.

• Whey (kefir). Dairy products are diluted with water in a ratio of 3:7. For greater effectiveness, you can add a small amount of sugar.
• Decoction of onion peels. 300 g of husk is poured into 5–7 liters of water, brought to a boil and left for at least 10 hours. Used as spraying and watering at the root.
• Manure. Mix 1/3 bucket of manure and water and leave for 3 days. Apply by diluting with water in a ratio of 1:10.

It is unlikely that it will be possible to quickly determine the cause of white leaves on a cucumber, since there can be many culprits. Therefore, it is advisable to identify, in addition to whiteness, other accompanying signs, if any, and only then begin active actions.

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Main diseases of cucumbers - photos, descriptions and methods of treatment

Adding an article to a new collection

Can you distinguish peronosporosis of cucumbers from bacteriosis by eye? Often errors in determining the disease become the reason for incorrect treatment. We will teach you to understand the symptoms so that the cucumber harvest does not suffer.

One of the most popular crops in the world is susceptible to a number of diseases that can destroy cucumbers at any stage of development. In order to identify the disease in time and begin treatment, you need to know the main signs indicating the onset of damage to the plant. So, what are the most common diseases of cucumbers?

Fusarium wilt of cucumbers

The subspecies of mold fungi Fusarium has long been a favorite of cucumbers, especially those that are weakened and growing in an environment favorable for the development of the fungus. It acts as a parasite, symbiont and generally does everything to destroy young plantings. Fusarium kills up to 60% of the crop, being most active in the south and southeast, as well as the Far Eastern regions. At an early stage, the disease is diagnosed by the drooping top at midday.

The upper part of the plant withers during the day and recovers at night. After the ovaries appear, the leaves turn yellow and the lashes dry out. Subsequently, the plants dry out and no longer grow.

Fusarium-resistant cucumber varieties: Parker F1, Hector F1, Dolomite F1, Alex F1, Christina F1.

Downy mildew of cucumbers

This is the scientific name for downy mildew . This disease affects the leaves of cucumbers, zucchini and pumpkins. Until 1980, it was known only to residents of the Far East, but the fungus quickly spread and became a frequent visitor in the middle zone and temperate climate zone. The main condition for cucumbers to be affected by downy mildew is high humidity, which allows zoospores to penetrate the leaves.

Downy mildew appears on the leaves in the form of light yellow spots, which darken as the tissues die. A gray-violet coating forms on the lower part.

Cucumber varieties resistant to blight: Azbuka F1, Lord F1, Chestnut F1, Compass F1, Acorn F1, Alphabet F1, Buyan F1, Grasshopper F1, Little Thumb F1, Ant F1, Moscow Evenings F1.

Cladosporiosis of cucumbers

Gardeners often know this disease as cucumber olive spot . It is caused by a fungus that is very resistant to adverse environmental conditions, although it is more common in southern and humid areas. It is less common in heated glass greenhouses with dry air.

More often the disease affects young fruits. They become distorted and small brown and dark brown spots appear on them. Less common are leaves and stems, which become covered with a network of small brown spots. Over time, these spots dry out and form sores and scabs.

Cucumber varieties resistant to cladosporiosis: Adam F1, Amazon F1, Amur 1801 F1, Cornflower F1, Aquarius, Hector F1, Danila F1, Makar F1, Marta F1.

Is it possible to eat pickled cucumbers if they are covered with a white coating on top?

Olga Dmitrieva

Can. Just wash it. This often happens in banks.

Amina Saryeva

More like mold. There is no better way. just in case.

Pupkin Ivan

It's better not to eat with mold

Albert Galyauw

It’s worth it; your health is worth more than throwing away a dozen cucumbers.

Leysan Davletshina

If the cucumbers are not soft to the touch, wash them, taste them, and decide whether to eat them or not. I do this, I still live)

Igor Kudryashov

Do not even think about it! The white coating is potassium cyanide!

.

It’s very good to wash it down with milk

Liana Golikova

not potassium cyanide, of course, but mold, you can’t eat it, the human body is an excellent environment for the life of mold fungi!

Yulichka Efremova

You can wash them in running water. And make a salad out of them. Chop add onion and pour over the plant. oil

Root rot of cucumbers

Root rot is a disease of extremes. As a result of abundant watering, soil moisture increases, and there is less and less air in it. The root system of cucumbers weakens and becomes vulnerable to phytopathogens. This is also caused by a high concentration of salts in the soil and drying out of the root system. The causative agents of the disease first settle in weak and dead areas, and then are mistaken for healthy plant tissue. In other words, it is easier for cucumbers to contract root rot than to avoid it.