To successfully grow cucumbers in a greenhouse, preventing the development of diseases, you need to take into account some factors that lead to weakening of plants, as a result of which they become more susceptible to bacterial, fungal and viral infections. The most common diseases in cucumbers and methods of their treatment and prevention should be considered. Having learned about the most effective drugs, you can decide what to spray the cucumber with in order to prevent the spread of diseases. To prevent disease in cucumbers in a greenhouse, you need to monitor air humidity, temperature and the presence nutrients in the soil. There may be several main causes of diseases of cucumbers in a greenhouse:

• increased air humidity; lack of nutrients in the soil; sudden temperature changes, including watering cold water.

Mosaic disease

The development of mosaic disease is promoted by sharp fluctuations temperature, lack of light and moisture in the soil. A viral disease that mainly affects leaves and fruits. It is transmitted through seeds and when diseased plants come into contact with healthy ones, and can be carried by insects.

Viruses penetrate plants through damaged tissue and remain in the soil and seeds. There are several strains of the virus; depending on the strain, symptoms may differ in the degree of deformation and the color of the mottling. The leaves may be slightly or severely wrinkled, with their edges curling down.

Mottling can be light and dark green, yellow or white. Due to the disease, cucumbers in the greenhouse set and develop poorly, often acquire a mosaic color and become deformed, but most often wither. The mosaic virus negatively affects the entire plant as a whole, its growth slows down.

The stems of the affected plant often crack. There are no effective methods to combat mosaic diseases. All that remains is to accept preventive measures, paying attention to varieties and hybrids that are resistant to mosaic.

To prevent the disease, only composted or sterilized substrates are used. In case of relatively mild infection, diseased areas should be cut out, and the spread of cucumber mosaic disease can be limited by spraying with skim milk. However, in case of severe infection, the plant should be destroyed.

Powdery mildew

Powdery mildew spreads quickly in cool, cloudy weather. Spores are spread by wind or water during watering. A fungal disease that manifests itself as a white coating on the leaves.

Over time, the amount of plaque increases until it completely covers the leaf, as a result of which photosynthesis is disrupted, the leaf turns yellow and dries out. Fungal spores can be spread by both wind and water during watering. With a severe degree of infection, spores may remain on the weeds or in the ground. This disease occurs due to the accumulation of infection when cucumbers have been grown in the same place for many years. Another cause of the disease can be high humidity in the greenhouse. To combat powdery mildew it is necessary to remove the affected leaves and spray the cucumber with mullein solution: mix 1 liter of liquid mullein with 1 tbsp. l. urea, mix everything well and strain thoroughly. You can also use a weak solution of potassium permanganate - 1.5 g per 10 liters of water - to spray cucumbers in a greenhouse.

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Downy mildew or peronosporosis

This is a fungal disease that mainly affects leaves. It appears as yellow spots on the top of the leaf; over time, the spots turn brown. There is a gray-violet coating on the underside of the leaf.

Over time, the leaves wither, dry out and fall off. The development of this disease is facilitated by increased humidity and sudden changes in temperature, watering cucumbers with cold water. To prevent powdery mildew, it is recommended to use potassium and phosphate fertilizers, ventilate the greenhouse more often, avoid cold drafts. To combat downy mildew, it is necessary to remove leaves affected by the disease and stop watering. Sprinkle the soil with wood ash, and spray the plants with Topaz solution in the ratio: 1 ampoule per 10 liters of water.

The fungicide "Oxychom" is also suitable: 2 tablets per 10 liters of water. After harvesting the last harvest, it is necessary to treat with the solution copper sulfate, dissolving 3 tbsp. l. in 10 liters of water. Cucumbers must be sprinkled generously, and after 24 hours, removed and burned along with the roots.

Root rot in plants

Root rot is caused by increased humidity in the greenhouse, watering with cold water, and planting seedlings in cold soil. A fungal disease caused by the fungus Pythium De Baryanum Hesse. The source of infection is spores that can spread through the air, with splashes of water, as well as through the transfer of insects. The development of the fungus is facilitated by planting seedlings in cold soil, sharp fluctuations in temperature and humidity in the greenhouse, and watering cucumbers with cold water. It begins to spread from the root zone, in As a result, they first turn yellow lower leaves, then the whole vine dries up, the roots become covered with brown spots, rot and die, as a result the plant dies completely. To prevent the disease, it is recommended to plant cucumber seedlings in soil watered with a solution of potassium permanganate, in a ratio of 3-5 g per 10 liters of water. Watering must be done correctly and on time. To combat root rot, you can use the drug "Infinito 61 SC". A solution in a ratio of 5-10 g per 10 liters of water. The combined use of such drugs is quite effective:

1. Fitolavin-300, 20 g + Fundazol, 15-20 g per 10 l of water. Fitolavin-300, 20 g + Colfugo Super, 15-20 g per 10 l of water.

Gray mold disease

To combat gray mold, it is necessary to sprinkle the affected areas with a mixture of copper sulfate and wood ash.A fungal disease caused by the botrytis mushroom (Botrytis cinerea Pers). Spores are mainly spread through the air, and can also be spread by splashing water. The development of this disease is facilitated by poor ventilation, increased humidity, a sharp drop in temperature, watering with cold rain water. The disease manifests itself in the form of brown spots on the leaves, rotting of the stems, and weeping brown spots appear on the fruits.

At high humidity the affected areas are covered with a gray fluffy coating, which contains fungal spores, which can be carried by drafts, infecting neighboring plants. For prevention, it is recommended to plant cucumbers at a sufficient distance from each other, avoid getting water on the leaves when watering and regularly ventilate the greenhouse.

To combat gray mold, the affected areas are sprinkled with either just wood ash or a mixture of copper sulfate (1 tsp) and wood ash (1 tbsp). After this, the greenhouse is well ventilated. Another option to combat this disease is to coat it with a fungicide.

To prepare it you will need: 300-340 g of CMC glue, 30-40 g of fungicide and 10 liters of water. The mixture must be brought to a paste-like state by adding crushed chalk to it. If none of the methods help, the affected areas must be cut off and burned.

White rot (sclerotinia)

Cucumber stems affected by white rot must be cut out, partially removing healthy tissue. A fungal disease caused by the fungus Sclerotinia sclerotiorum. The source of infection is the soil in which the spores of this fungus persist and live for quite a long time. The development of the disease begins at the root part of the stem, watery wet spots form there, and over time they become covered with white cotton wool-like mycelium.

Next, the upper tiers of the plant are affected. White rot causes death and wilting of plants, rotting of fruits. To prevent infection by the fungus, it is necessary to observe optimal mode humidity and temperature in the greenhouse.

Since fungal spores can be in the soil, if possible, it is necessary to use calcined soil, and when planting seedlings in holes, you need to add potassium permanganate, dissolving 5 g in 10 liters of water. To combat white rot with mild damage, you need to mix chalk and potassium permanganate with the addition of water and treat the affected areas with the resulting paste. In case of severe damage, it is necessary to remove the affected areas, it is advisable to also include part of the healthy area.

Sprinkle the affected stems and areas with lime. But if the plant is very sick, it will be better to remove it along with a layer of soil to avoid infection of neighboring plants. When fighting white rot, it is also recommended to use drugs such as Rovral SP and Euparen Multi SP produced by Bayer.

Fusarium fungal disease

Measures to combat fusarium: watering warm water, soil disinfection, adding trichodermin to the holes when planting seedlings. A fungal disease caused by fungi of the genus Fusarium. Its sources are seeds and soil.

The development of the disease is facilitated by sudden changes in temperature, high humidity and lack of soil nutrition. Weakened plants are most susceptible to the disease. The causative agents of the disease enter from the soil first into small roots, then into larger ones.

From the roots, through conducting vessels, they enter the stem, reaching the leaves. The lower leaves of the plant wither, the edges of the rest become watery, and some areas turn light yellow or pale green. The stem becomes thinner and turns brown.

Soon the entire plant withers and dies. To prevent the appearance of fusarium, it is necessary to regularly ventilate the greenhouse and calcinate or freeze the soil before sowing or planting seedlings. In addition, it is recommended to sterilize tools with alcohol before work - used knives and garter material). If there are visible damage to the plants, fusarium is no longer curable. Affected plants must be destroyed immediately to prevent the spread of the fungus.

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Olive spot (cladosporiosis)

A fungal disease caused by the fungus Cladosporium cucumerinum Ellis & Arthur. Favorable conditions for the development of the disease are watering the cucumbers in the greenhouse with cold water, high air and soil humidity, low temperatures and drafts. This disease manifests itself in the form of oblong dry sores with a grayish-olive coating covering the stems.

Light brown spots appear on the leaves; later they are covered with a faint brown coating. Fruits are most affected. First, oily depressed spots appear on them, then an olive coating develops, various ulcers of irregular shape form. To combat cladosporiosis, it is necessary to stop watering for several days, regularly ventilate the greenhouse, and spray the cucumber with a 1% solution of Bordeaux mixture, you can use “Oxyx” - 20 g per 10 liters of water.

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Anthracnose or copperhead

A fungal disease caused by the fungus Colletotrichum orbiculare. Its spores can spread with the wind, irrigation water, and can be carried by insects or on garden tools. The development of this disease is facilitated by high humidity and a lack of nutrients in the soil.

It begins with damage to the leaves; light brown spots with a border of a darker color form on them. Spots appear on the shoots, which expand and deepen over time, forming depressed spots, then they are bordered by a dark purple or brown rim.

Deep ulcers with mucus appear on the cucumber fruits themselves. Pink colour.In dry weather, cracks appear in the affected areas, and in high humidity, the stems rot and break. When the disease develops severely, the entire aboveground part plants. For prevention, it is necessary to observe the humidity regime in the greenhouse and avoid sudden temperature changes.

If possible, use calcined soil. And as a preventive measure, you can spray cucumbers in the greenhouse with Oxychom, Kuproxat or copper oxychloride. In case of infection, it is necessary to carefully remove the areas affected by the disease.

Why cucumber leaves turn yellow is often not so easy to understand, because there are many reasons and it seems that they all fit your case. But we have to do something, we don’t want to lose the harvest.

How to prevent yellowing of cucumber tops and what to do if the cucumber leaves have already begun to turn yellow? Let's find out now.

Why cucumber leaves turn yellow: 6 reasons

The first reason is trivial - some of the lower leaves inside the bed turn yellow and die from lack of light. This is not a cause for concern at all, it is normal.

As a rule, a cucumber bed is a real lush jungle; it is not surprising that light penetrates inside with difficulty and the lower old leaves do not have enough of it. In this case, just pick off the yellow leaves from time to time and enjoy the harvest. The second reason is a lack or excess of moisture.

In normal summers, it is recommended to water cucumbers generously two to three times a week, and in hot summers - every day, thoroughly soaking the soil. Otherwise, the roots of the cucumbers will begin to “climb” to the surface of the earth in search of moisture and may dry out.

This is a disaster for plants; both leaves and ovaries begin to turn yellow. Rainy weather is also not to the liking of cucumbers: the roots rot, rot forms on the stems, and as a result we again see yellow leaves. Reason three - fungal diseases.

Most often, fusarium, pythiosis and other fungal diseases are the cause of yellow leaves on cucumbers. First, rusty spots appear on the tops, then the leaves become completely covered in spots, dry out, and fall off.

Moreover, in the case of fusarium, the lashes become lethargic, like a rag, and do not respond to watering. If thirty-degree heat has given way to cold rains and lower night temperatures, hold on: fungi will not keep you waiting. The fourth reason is pests.

Whitefly or spider mite suck all the juices out of cucumber leaves, as a result the leaves turn yellow and die. IN in this case the recommendations are obvious: good pest- dead pest.

You will either have to spray the garden bed with “poison” or resort to folk remedies. Reason five - shortage nutrients. The most unlikely, but still common cause of yellowing cucumber leaves.

If the edges of cucumber leaves turn yellow and dry out, they may be lacking potassium or magnesium. Dark green veins against a yellow background may signal a deficiency of iron or manganese. Yellowing of the upper leaves occurs due to a lack of copper.

Feeding will help correct this situation. And the last reason for yellow leaves is old age. Over time, the cucumber leaf becomes coarser, ages, stops photosynthesis, turns yellow and dies. Most likely, by this time you have already eaten your fill of cucumbers, and the aging lashes do not bother you.

But if you want a fresh cucumber straight from the garden before the fall, there are ways to “extend the life” of cucumber vines, and we will talk about them later.

What to do if cucumber leaves turn yellow

The best treatment for everything in the world is prevention, and yellowing of cucumber leaves is no exception. It’s easier to prevent this from happening in your garden than to treat it later. Therefore: 1.

Try to maintain crop rotation. Do not plant cucumbers in the same place from year to year, do not plant them after zucchini or pumpkin, otherwise the likelihood of “catching” a fungal disease significantly increases.2. Water your cucumbers promptly and abundantly.

If you are on the site only on weekends, take the time to mulch the beds well with weeds or mown grass. A thick layer of mulch will prevent moisture from evaporating, and will also provide the cucumber roots with additional nutrition and warmth.3.

After emergence of shoots in the 3-4 leaf stage (and then every 10 days), spray the cucumbers with the following composition: 20 grams laundry soap, 1 liter of milk and 30 drops of iodine per 10 liters of water.5. Another option for preventive spraying: soak a loaf of bread in a bucket of water in the evening, knead the bread in the morning and add a small bottle of iodine.

Dilute one liter of this mixture in a bucket of water and process the cucumbers. If you repeat this procedure once every two weeks, you can keep the cucumbers green until autumn.6. In June, soak the cucumbers with a soda solution (1 tablespoon per 10 liters of water).

Then the onion peel is squeezed out, the broth is filtered and diluted in a ratio of 2:8 with water. Spray the leaves from above and below with this solution, and then spill the soil.8.

If you still can’t protect yourself and the leaves begin to turn yellow, try spraying the cucumbers with a solution of whey or kefir (2 liters per 10 liters of water). For better fruit set, you can add 150 grams of sugar to the solution.9.

When the leaves just begin to turn yellow, watering with a weak solution of potassium permanganate can help. 10. To prolong fruiting and rejuvenate aging cucumber leaves, carry out foliar feeding urea, while simultaneously adding humus under the roots.

Spraying rotted hay with an infusion does an excellent job of accomplishing the same task. To obtain the infusion, the hay is soaked in water (1:1) for two days. Spray cucumbers three times at weekly intervals.

11. To protect against pathogenic fungi and bacteria, use biological preparations (for example, trichodermin). They suppress harmful microorganisms, but are safe for humans and animals. We wish you success and big harvests!

It’s such a shame when cucumbers in a greenhouse turn yellow. What is the cause of this disaster and what can be done to save the situation and still get a good harvest? If the yellowing of the leaves is not accompanied by wilting, most likely the reason is a lack of nutrients. Why do the fruits and leaves of cucumbers turn yellow? Experts identify several of the most common causes.

Failure to comply with the technology of growing cucumbers in greenhouses

Cucumber is a very moisture-loving plant (like pepper), so you should not neglect the rules of watering this vegetable. These rules are simple: to prevent the cucumbers from starting to get sick and turn yellow, the water for watering should not be cold (watering from a hose is not suitable). Water should be settled.

During the fruiting period, watering should be increased more often. In cool weather, plants are watered in the daytime, and on sunny, warm days - in the morning. If the days are hot, then in the mornings only refreshing watering is done, and in the evenings - normal.

The depth of the moistened soil should be sufficient to root system cucumber plants developed deeply, and not superficially. Regularity of watering is crucial: you only have to miss watering the plants a few times, and this will immediately affect the quality of future fruits. So, lack of moisture leads to yellowing of the plant itself and the new ovary of cucumbers. Yellow spots indicate a lack of potassium, and light green spots are a sign of magnesium deficiency.

This means that cucumbers need to be fed. Weather conditions are often the reason why cucumbers turn yellow. Cold, wet weather caused by late frosts can damage plants.

If rotting of the ovaries occurs, you need to urgently remove the already faded flowers and treat the cut with potassium permanganate (solution). To prevent further bacteriosis, spraying is carried out with either 1% Bordeaux mixture or 0.4% copper oxychloride.

It's worth noting that peppers can also turn yellow and lose leaves if they are kept in temperature conditions up to +120°C for a long time. The composition of the soil is critical. Lack of nitrogen and poor soil - here common reason why plant development is disrupted.

It is important to ensure that there is no overdose in the amount of fertilizer, which, in turn, leads to oppression and yellowing of seedlings and their fruits. Before planting cucumber seedlings and after the harvest is harvested, manure must be applied to the soil. And during the growing season, fertilizing with complex mineral fertilizers containing phosphorus, fluorine and potassium, and liquid mullein is considered mandatory.

Damage to plants by various diseases or pests

Powdery mildew. If light, resembling white coating spots that gradually increase in size are a sign of infection. The leaf dries and turns yellow.

How to deal with this trouble? If you do not worry about measures to destroy powdery mildew, it will certainly make itself felt next season.

Fungicide preparations “Topsin”, “Bayleton”, “Karatan” will help. The main disease of cucumber in our area, in which the leaves turn yellow, is downy mildew (downy mildew). It is also worth paying attention to cucumber varieties that are resistant to this disease. Fusarium wilt. Dangerous fungal disease, causing the death of cucumbers in a greenhouse.

Penetrating into the capillaries of the plant, the spores of this fungus completely block the access of food to the fruits and leaves. In greenhouses where infection has occurred, it is required complete replacement soil. In addition, you need to regularly change the variety of plants. Melon aphids.

Special preparations work well against these pests: Belofos, Arrivo and the like. Root rot. The leaves, both of young plants and adults, begin to turn yellow from below. This is caused by significant temperature differences between day and night.

The cause may be watering with too “cold” water. Weakened plants become sick first, then the infection begins to spread through the soil to other cucumbers.

Preventive treatment (twice) with Previkur in the root area can prevent this unpleasant disease. Downy mildew (pernosporosis). This disease, common in melons and cucumbers, appears in greenhouses under conditions of high air and soil humidity, against the background of dense planting of seedlings.

Affected fruits shrink and turn yellow. The first signs of damage may appear immediately with the onset of fruiting. In this case, the crop may be completely destroyed.

How can you tell if your plants are sick? Acute-angled, dark green spots appear on the lower leaves. Preparations to combat pernosporosis - Bordeaux mixture or copper chloride (for the first treatment), "Bravo", "Avixil" (for the second treatment after 7 days).

​Similar articles​

​Fusarium​

Possible reasons

​Don’t forget to monitor the microclimate. Cucumbers love water, so don't skimp on watering. However, remember that the plant needs to be watered only with warm water, at outside temperature. If you water a plant with cold water, diseases cannot be avoided.

​3. insufficient amount of moisture at high ambient temperatures.​

Violation of agrotechnical conditions

Low temperatures and frosts

The question of why cucumbers turn yellow in a greenhouse worries every gardener and gardener who grows them indoors. Reasons causing yellowing There may be several leaves, ovaries and cucumbers grown in greenhouse or greenhouse conditions. - a fungal disease, fungal spores block the capillaries, and nutrients do not reach the plant. Toxins affect the plant at any stage of development, which leads to its death. To protect the next harvest of cucumbers from fusarium blight, change the soil and select other varieties. At the seedling stage, the plant is especially sensitive to potassium deficiency; if you do not monitor the development, the cucumbers will grow in an irregular shape. Best suited for cucumber seedlings nutrient solution based on complex fertilizers. For example, Kemira Hydro.​
Insufficient watering affects the yellowing of seedlings in the same way as severe waterlogging.

​So, the choice right place planting, timely deep watering of cucumbers and their feeding will significantly ensure wellness plants. When applying fertilizers, be careful about the dosages.​

​or water a lot, but rarely. It turns out: the crop is flooded with water at some point, but during hot summers, the water quickly disappears and as a result the plant does not receive the necessary moisture or the roots begin to rot. Subsequently, the spots become oily and light yellow, and eventually turn brown . On the bottom side sheet plate, in those places where there are spots, a grayish-brown coating forms. If no measures are taken, the plant will die within a few days. It is necessary to pinch out new shoots in a timely manner to allow cucumbers to form and ripen normally. If excess shoots and ovaries have not been removed, the fruits may develop an unattractive shape, and cucumbers in the greenhouse may turn yellow.

Lack of mineral elements in the soil

​It is necessary to moisten the soil quite deeply, since it is the deep penetration of water that will contribute to the development of not only the surface, but also the deeper root system of plants.​
​Also, the reason why the leaves of cucumbers in a greenhouse turn yellow may be insufficiency minerals in the soil in which the plants were planted. As a rule, the leaves of cucumbers in a greenhouse turn yellow due to a lack of nitrogen.​
​Having listed the main reasons why cucumbers turn yellow in a greenhouse, let’s look at each of the listed problems in more detail.​

​It is very important to properly organize watering of cucumbers so that the fruits are undeformed and tasty, and the leaves are green. The norm for watering cucumbers is about 25 liters per plant with twice a week watering.​
If cucumbers in a greenhouse turn yellow, root rot may also be the cause of this phenomenon. Plants at any stage of development can suffer from this disease.​
So, let's figure out what insects and diseases can harm cucumbers, and how to deal with them (see Diseases of cucumbers in a greenhouse, causes and methods of treatment).
Irregular and insufficient watering will affect both the leaves themselves and the ovary and fruits of cucumbers.

Poor pollination

​Yellowing begins with the leaves having a lighter color, and then completely turning yellow, both the veins themselves and the entire space of the leaf between them. Subsequently, all the lashes of the plant turn yellow. Another sign indicating a nitrogen deficiency in the soil is incorrect, “hook-shaped” fruit shape.​
​Cucumber, as you know, is a warm and moisture-loving plant. In conditions middle zone, especially at the end of May, the so-called ​Reasons:​ Leaves affected by the fungus turn yellow and curl. Since the disease affects cucumbers from July, treatment of the plant should begin at the end of June. Bordeaux mixture, "Kuproksat" - the first part of preventive and therapeutic measures, the use of "Acrobat", the drug "Bravo" - the second stage of treatment of pernosporosis. It is best to choose cucumber varieties that are resistant to the disease.​
Cucumber leaves turn yellow at the edges

Plant overload with ovaries

​Poisoning by toxins. Some farmers place seedlings on foam boards. Yellowing can be caused by poisoning with chemical compounds released by the insulating layer, since the roots of the plant come into contact with it. Fertilizer getting on the foam can lead to the release of harmful substances, which is dangerous not only for seedlings, but also for the crop.​

​In addition, they apply biological methods soil disinfection, in which the soil is carefully removed from the greenhouse and placed outside in a stack no more than a meter high. Each layer is spilled with biologically active microorganisms (Baikal EM-1 preparations, humus tinctures, etc.), compost can be added. Such disinfection takes 2-3 years.​

​You also need to test the soil for moisture, periodically take a piece of soil from a depth of ten centimeters and squeeze it in your hand, determining whether the soil is wet or not, in order to avoid overwatering or underwatering.​
The reason for such damage to cucumbers can be a significant difference in night and day temperatures, as well as watering the plants with cold and unsettled water. Weakened plants are the first to be affected, and then other plants become infected through the soil.

Damage to plants by insects or fungal infections

​This disease manifests itself as follows: cucumbers sprout normally and grow well, but as soon as the ovaries begin to appear, the leaves of the cucumbers in the greenhouse first turn yellow, after which the vines dry out.​

Fungal diseases

Fusarium wilt or fusarium is a fungal disease

​One of the reasons why cucumber ovaries turn yellow in a greenhouse may be poor pollination flowering plants. This can happen due to the fact that only artificially pollinated plants were planted, as well as due to the lack of ventilation or access for insects to pollinate the plants (see How to attract bees to grow a good harvest).​
A lack of nitrogen in cucumbers can be caused by excessive application of wood ash, potash fertilizers or superphosphate.
​"return frosts"​
​Insufficient pollination, and as a result, poor setting;
The melon aphid sucks out all the juices from the seedlings, so the leaves of the cucumbers on the windowsill turn yellow.

​Seedlings can be cramped in a peat cup, so many summer residents immediately sow seeds in the ground. The roots need space and adequate nutrition. Yellowing of the leaves may indicate that it is time to replant the plant.​

Downy mildew (pernosporosis)

​Remember that the spread of fungal diseases is facilitated by mechanical damage to the roots and trunks of cucumbers. Since their roots are very susceptible to damage, it may be better to do without loosening the soil. In this case, pay more attention to preparing the soil before planting.​
​The wrong area for cucumbers has been selected. Crops need to be alternated, and for cucumbers the area should be one where the sun does not shine strongly at its peak;

​In order to prevent plants from being affected by this disease, it is necessary to treat the root area with Previkur twice per season, according to the instructions.​
​The fungus that causes this disease penetrates the plant and releases toxins that limit the supply of nutrients and microelements to the leaves and stems. The way to combat this fungal infection is to regularly change the varieties planted in the greenhouse, as well as partially replace the affected soil.​
​In this case, you can use spraying with boric acid dissolved in water (5 grams per 10 liters of water), or ​

Insect pests

melon aphid

​.In order to avoid nitrogen deficiency in cucumbers, it is recommended that cucumber seedlings, a few days before planting in greenhouses, be fed with fertilizers and sprayed with a solution of microelements (see How to choose the right fertilizer for cucumbers in a greenhouse).​.

​. Cucumber seedlings planted under film covers or in greenhouses may not only turn yellow, but also stop growing and developing.​

​Overload of plants with ovaries;​

​Spider mite.

​

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Why do cucumber leaves turn yellow?

• Many gardeners make mistakes when watering cucumbers.
• ​Lack of light.​ ​In addition to alternation vegetable crops

, for the biological protection of cucumbers, it can be recommended to use biofungicides containing trichodermin. It is necessary to introduce mycelium into each hole at a distance of 3-10 cm from the shoots. Trichodermin suppresses the development of pathogens and has a stimulating effect on the development of vegetable crops. Non-phytotoxic, harmless to insects, humans and animals.​

​moisture gets on the leaves and in strong sun the leaf gets burned; it is better to water in the evening or early hours of the day;​

​This pest prefers to “infest” the underside of cucumber leaves and feeds on plant sap, which is why cucumbers turn yellow in greenhouses. The melon aphid poses a danger to cucumbers throughout the summer season.​

• Powdery mildew is also a fungal disease. With this disease, the fungus blocks photosynthesis processes in the plant.​
• ​drugs "Bud" or "Ovary"​
• ​When digging up a greenhouse in autumn and spring, it is necessary to add rotted manure to the soil at the rate of two or three buckets per 1 m2. This will help avoid nitrogen starvation in plants.​
• ​To avoid cucumber leaves turning yellow in the greenhouse, it is necessary to additionally cover the planted plants with lutrasil or bubble wrap. Many gardeners sub-zero temperatures and frosts, place plastic bottles with hot water, in order to maintain a normal temperature for the growth and development of cucumbers.​
• ​Infection of plants by insects or fungal infections;​

Protection of cucumbers

It is better to prevent yellowing of the leaves by observing the growing conditions and providing the cucumbers with the necessary nutrients. In addition, it is necessary to monitor the state of the microflora of greenhouses and the site, to prevent the development of pathogenic fungal diseases. Then you will always have healthy plants and a high harvest of cucumbers.​

​cucumbers suffer from elevated temperature air (this is usually very noticeable in greenhouses). A systematic air flow and regular ventilation are required;

​This pest appears primarily on the inside of the cucumber leaf, where it weaves small webs.​

​First of all, on cucumber leaves small light spots appear, which gradually spread over the entire surface of the leaf.​

​.Of natural methods, you can use spraying with sweet water (one tablespoon of sand or honey dissolves in two liters of water), which will attract insects.​

OgorodSadovod.com

Leaves of cucumber seedlings turn yellow | L.S.

​If manure was not introduced during the digging process, then before planting the seedlings in the greenhouse, you can add rotted mullein to the soil, and throughout the growing season, feed the plants with an aqueous solution of mullein or chicken manure, as well as an infusion of herbs, which is also called “herbal tea.”​

​Attention: It is important to remember that this plant prefers temperatures within +22+260C for its development. If the temperature drops below +140C, or above +420C, the plant stops its growth and development. If the temperature is below -10C, cucumber seedlings will die.​

Why do cucumber leaves turn yellow?

​Possible violation of agricultural practices for growing cucumbers:​

1. ​You need to water more often.​
2. At first, the leaves become covered with a white coating, and then the disease leads to yellowing of the foliage. Powdery mildew is a fungus that slows down plant growth. It is better to use varieties that are resistant to this disease. As soon as you notice a white coating, use the preparations “Karatan” or “Bayleton”. Processing is carried out in dry weather in the evening. Powdery mildew is the most common disease of cucumbers, which leads to yellowing of the leaves and damage to the ovary. The most dangerous time to become infected with powdery mildew is during the fruiting stage. Rainy weather increases the severity of damage.
3. ​Balance the doses of fertilizers, do not exceed the ammonia content in the solution. If there is a lack of nitrogen, you need to fertilize the plant with Vermistim or Azogran.​
4. ​Cucumbers grown in the country are fragrant and healthy. They taste significantly different from vegetables bought in the supermarket. But growing healthy cucumbers is not so easy; the plant is susceptible to many diseases. Summer residents often face the problem that the leaves of cucumber seedlings turn yellow.​
5. ​Cucumbers lack mineral fertilizers. Thus, a lack of nitrogen will noticeably affect the development of the entire plant: the vines will be thin, the foliage will first become a light salad color, then turn yellow and fall off. More yellow spots on cucumber foliage may indicate a calcium deficiency. The appearance of a yellow edging on old lower leaves of cucumbers characterizes magnesium deficiency. Conversely, if young cucumber leaves turn yellow, then this is a lack of copper. Dark green veins on cucumber leaves with spots yellow color are characteristic signs of iron deficiency. The lower leaves of cucumbers also die, the tips of the leaves turn yellow due to a lack of zinc;

On all leaves of the plant, a whitish or reddish coating is observed on the upper surface of the leaf blade. After which the leaves of the cucumbers in the greenhouse turn yellow and dry out.

Cucumber leaves turn yellow: what to do?

• ​Next season, in the greenhouse in which you plan to plant cucumbers, plant dill or some honey plants, for example, borage, hyssop. These plants will be able to attract insects to the greenhouse, which will be able to pollinate the plants and promote the formation of normal ovaries.​
• ​It will also help eliminate the lack of nitrogen in the soil by applying mineral fertilizers containing nitrogen. The leaves of cucumbers turn yellow in greenhouses and greenhouses even when too much mineral fertilizer is added to the soil.​
• Thus, in order to protect cucumbers planted in a greenhouse from frost and low temperatures, they should be additionally covered with a film placed on the arcs or with a special non-woven
• ​1. frosts or low average daily temperatures;
• They begin to turn yellow.

​Root rot.

• ​
• First, white or light yellow spots appear on the leaf, and then the leaves become completely covered with yellow spots and dry out. Throughout the warm days, spider mites multiply and if you do not fight them, for example, with the drugs “Akarin”, “Tsimbush”, “Fitoverm” and others, then you can lose all the plants in the greenhouse.​
• ​In the literature devoted to gardening and growing cucumbers in greenhouses, when asked why cucumbers turn yellow in a greenhouse, they answer that it is not advisable to leave more than 20-25 ovaries on one plant at a time.​ ​Before applying this or that fertilizer, read carefully manufacturer's instructions on the packaging.​​covering material such as lutrasil, agrotex or spandbond.​ ​2. flaw mineral elements
• in the ground; Need to water more, apparently insufficient watering
• The cause of the disease can be changes in day and night temperatures, watering the plants with cold water. Affects weak seedlings. Prevention is by treating the roots with Previkur. Treatment takes place in two stages with an interval of 2 weeks.​
• ​If the seedlings grow on the balcony, then you can use lighting.​ There can be several reasons for the burning of leaves, the main ones include:

Of the diseases that cause yellowing of cucumber leaves, fungal diseases should be mentioned first of all. They develop greatly when crop rotation is not observed. Fungi and pathogens accumulate in the soil.​
Quite often, some gardeners doubt why cucumber fruits are light green. However, there is nothing too difficult in this matter.

Check out our article, we hope it will be useful.

How to fertilize cucumbers to make them beautiful and tasty? Cucumber ovaries grow very quickly, a week is enough for them, so when you remove already ripe cucumbers, you see new strong ovaries that require feeding. If cucumbers are not fed, they will become “ugly” - they will become crooked and tasteless. However, you should not apply a lot of different fertilizers, because plants need little, but. It should also be taken into account that at the beginning of the growing season, the cucumber needs more nitrogen, during the period of loop growth, the cucumber requires more potassium, then during the period of fruiting and the appearance of new growths, more nitrogen is again required.

How to fertilize cucumbers?

You can use a compost mash; you should add fertilizer once a week per square meter bucket. Ash mash also a good option fertilizers for cucumbers. It should be applied once a week: dissolve a glass of ash in a bucket of water and apply it to two square meters.

Feeding during different periods of the growing season

During the flowering period: dissolve one teaspoon of urea, potassium sulfate, superphosphate and a glass of mullein in ten liters of water. During the fruiting period it is carried out three times.

First: dissolve a tablespoon of nitroammophoska and a glass of chicken manure in ten liters of water and add five liters of the mixture per square meter. The second is carried out 12 days after the first: dissolve a teaspoon of potassium sulfate and 1/2 liter of mullein in ten liters and add five liters per square meter. The third feeding is applied 12 days after the 2nd feeding: a tablespoon of nitroammophoska, a glass of chicken manure or 1/2 liter of mullein is dissolved in ten liters of water, five liters of the mixture are added per square meter.

If after fruiting the leaves of the plant become rough and prickly, then they should be sprayed with a urea solution: a tablespoon per ten liters of water. If the soil is low in nitrogen, the cucumber leaves will turn pale green, then turn yellow and fall off. If there is not enough phosphorus, then the leaves will be dark green with an admixture of violet shade When they fall off, the leaves will turn black. A lack of potassium in the soil will lead to the appearance of a pale green border along the edge of the leaves, which will change color to brown, and brown spots will also appear.

Weak growth of cucumbers, dying and drooping of the plant indicates a lack of calcium in the soil. Signs of magnesium deficiency will be yellow spots on the leaves, their browning and death. If there is not enough iron in the soil, then the leaves on the tops of the shoots turn yellow, but do not die. During the period of ovaries and fruiting, the lack of nutrients can be determined by the shape of the fruit. If the fruit becomes thinner near the stalk and becomes pear-shaped, then there is not enough potassium. It is better to introduce not mineral water, but mash from ash. If the fruit is deformed at the tip, then there is not enough nitrogen. Planting nitrogen-fixing plants such as beans and beans will help here.

Constrictions in the middle part of the fruit indicate “burns” of the root system when watered with cold water. In this case, it is necessary to water with settled water in the evening. You can also familiarize yourself with the selection of fertilizers for cucumbers, feeding cucumbers for open ground and greenhouses, pre-planting soil preparation for cucumbers.

Warning

Failure to comply with the doses of applied fertilizers leads to the accumulation chemical elements in the soil, has a detrimental effect on the development of plants and can lead to human poisoning. Excess potassium fertilizers affect the ability of plants to absorb nitrogen. The shoots of cucumbers become thinner, the foliage becomes much lighter. With excess nitrogen, the stems of cucumbers thicken, greenery grows wildly, and fruit ripening is delayed. The fruits become smaller and nitrates accumulate in them. Cucumber vines become susceptible to fungal diseases. Such a harvest is dangerous, you can get poisoned. With an excess of phosphorus, necrotic spots appear on cucumbers. The plant becomes very susceptible to lack of water.

http://www.gardening.kittens-world.ru/pochemu-na-l...lit-nedostatok-jelementov.html

Cucumber leaves are like a litmus test for determining their health. In addition to water, air and sun, cucumbers need macro- and microelements throughout the growing season. And, if the leaves are faded, deformed or have yellow spots or borders, then this is not necessarily some kind of cucumber disease. This article will help you understand why cucumber leaves have a yellow border or other shades, and will also tell you how to correct this effect and get excellent harvest cucumbers

Yellow border on cucumber leaves.

This year I myself had to face this problem. The spring was protracted, the beginning of summer was cold: the cucumbers were slowly germinating, and when I finally waited for the first real leaves, I saw this yellow border along the edge of the cucumber leaf. I decided that this was due to lack of light and warmth. The leaves were pale and weak, it was difficult for them to even absorb the necessary nutrition.

The first reason is that if a yellow and then a brown edge appears on the leaves of cucumbers, it means they lack potassium.

I spilled the cucumbers from a watering can and sprayed them over the leaves with a weak pink solution of potassium permanganate, that is, potassium permanganate. Additionally, I scattered 1 tbsp of ash under each plant. Now the cucumbers are fine.

But there is a second reason for the appearance of a yellow border on cucumber leaves - a lack of boron. This happens when flowers and fruits already appear on the plant. The lack of boron can be determined not only by the leaves, but also by the ovaries, since in this case the flowers appear, they immediately wither and die, and the cucumbers themselves are crooked, delayed in development and have a yellow longitudinal furrow.

In this case, spraying on the leaf will help (you can try Boric acid or even better - Biochelate-Boron). Just be careful, since boron is a highly toxic element that, if overdosed, will cause leaf burns.

Cucumber leaves are pale, sometimes thin, and deformed.

Such leaves may appear at the beginning of the development of cucumber vine - this is a lack of nitrogen. At the very beginning of cucumber growth, feed it with nitrogen-dominated fertilizer. This can be carbamide (urea) or ammonium nitrate.

I do this - when planting cucumbers nearby, I dig a small furrow and sprinkle ammonium nitrate (or nitroammophoska) into it. In the future, once when watering, I add 1 tablespoon of urea to the watering can.

“Among all mineral fertilizers, nitrogen fertilizers are the most dangerous in case of overdose: excess nitrogen accumulates in vegetables in the form of nitrates and nitrites, which are harmful to human health. Nitrates accumulate in plants not only when there is an excess of nitrogen, but also when there is a lack of molybdenum and iron, which contribute to the reduction of nitrate nitrogen (NO3) to ammonia nitrogen (NH4).” http://www.agroplus-group.ru

Cucumber leaves are small, light yellow-green, and can curl.

This can also be at the beginning of the development of the cucumber lash or, conversely, at the end of the harvest, as well as when very large quantities fruits This means that the leaves have become “impoverished” and have given away everything valuable that was embedded in them.

In this case, you need to give the plant a portion of microelements - zinc, calcium, sulfur. It is better if the fertilizer is in liquid form - in this case, quick help is needed - then you can not only spill it on the soil, but also spray and fertilize the leaves.

Cucumber leaves are “marbled”: the color is uneven, green light and dark spots alternate.

The leaves are deficient in magnesium. If you dust the soil with dolomite flour before planting, and then water it with a liquid dolomite solution (1 tbsp per 8 liters) once every 20 days, then this will not happen. Dolomite flour- a good supplier of magnesium.

Cucumber leaves are small, gray-green, on adult plants there are brown spots between the veins, on young plants the leaves “look” up.

This is phosphorus deficiency. Cucumbers most of all need a regular supply of phosphorus. All the time they grow in the plant there is a very high consumption of all macroelements, and especially phosphorus - it is the key good quality fruits Feed the cucumbers with superphosphate or other phosphorus-containing fertilizer. In young plants, the leaves will unfold in a horizontal plane, which means they will receive more sun and light. Do this once every 10 days.

The veins on the leaves of cucumbers are dark green and stand out strongly on the surface of the entire leaf; the leaf itself can be light green or yellowish.

This type of leaves occurs due to a lack of manganese. Manganese is involved in the formation of chlorophyll and, like iron, copper, zinc is necessary for cucumbers for photosynthesis and respiration. Most often, manganese deficiency occurs in alkaline soils.

You'll make your life a lot easier if you find something good. complex fertilizer, with which you won’t have to rack your brains about why there is a yellow border on the leaves of cucumbers and what the lack of elements in your cucumbers is.

For myself, I discovered a very convenient to use, inexpensive and effective fertilizer brand "JOY". Fertilizer can be selected according to different type grown crops. "JOY" can be used in protected and open ground. It contains an optimally balanced amount of micro- and macroelements. "JOY" works throughout the entire vegetative period of plant development. Fertilizer helps to increase the yield by 30% and increase its shelf life, as well as restore the natural structure of the soil. In my case, the “JOY” - Universal bottle has a convenient dispenser cap, which is also important. And of course, when choosing a fertilizer, I paid attention to the “hazard class”, here it is IV (low-hazard).

If the leaves of cucumbers are too light and small, this is a lack of NITROGEN. In this case, the fruits develop a narrowed, light, beak-curved tip. Feed the plants with manure (1:10), weed infusion (1:5), urea or ammonium nitrate(2 tablespoons per 10 liters of water).
If a brown border (marginal burn) appears along the edges of the leaves, this is a deficiency of POTASSIUM. In this case, the ends of the fruit swell spherically, taking a pear-shaped shape. To fix this, give potassium fertilizer (3 tablespoons of any chlorine-free potash fertilizer per 10 liters of water) or sprinkle 0.5 cups of ash around the plants.
If the leaves are directed upwards, this is a lack of PHOSPHORUS. Feed with superphosphate (3 tablespoons per 10 liters of water).
If the leaves have a marbled dark and light green color, this is a deficiency of MAGNESIUM. Dilute dolomite (1 cup per 10 liters of water) and pour this white milk over the soil around the plants.
If the leaves have acquired a yellow-green color, this is a lack of MICROELEMENTS. Feed the plants with microelements. that you have, dissolving them according to the attached instructions.
ALL THESE FEEDINGS SHOULD BE DONE IN THE EVENING, AFTER WATERING.
But it is most effective in all cases to give foliar feeding on the leaves with a solution of “Uniflor-rost” or “Uniflor-bud” (2 teaspoons per 10 liters of water).
TYPICAL FAILURES
THE FRUITS HAVE A PEAR-SHAPE - they have a swollen tip. This is a lack of potassium.
THE TIP OF THE FRUIT IS NARROWED AND BENT, like a beak, and the end usually turns lighter - this is a lack of nitrogen.
THE FRUIT IS NARROWED IN THE MIDDLE - the reason is the large temperature difference between day and night; sometimes this happens due to watering with warm water.
CUCUMBERS ARE CURVED, IRREGULAR, ARC-SHAPED - cross-pollination of hybrids by insects has occurred. Such cucumbers should be removed immediately and used in salads. In varieties, this phenomenon is observed when the soil dries out or is unevenly watered: sometimes it’s dry, sometimes it’s too wet.
GREENS STOP GROWING - This often happens in cold weather, especially on cold nights. Sometimes this happens when there is a lack of moisture in the soil and air.
THE OVIES TURN YELLOW, DO NOT DEVELOP, DRY AND THEN FALL AWAY. Fertilization did not occur due to too high temperature(above 36 degrees), either due to too high humidity (above 90%), or due to prolonged cold weather and prolonged rains (pollinating insects do not fly in such weather). Sometimes this happens with bunch fruiting: one or two fruits grow, and the rest from this bunch dry out - lack of nutrition, there is simply not enough for everyone.
CUCUMBERS APPEAR STRONG BITTERNESS. Cucumbers contain a valuable element - cucurbitacin, which has an antitumor effect. When its concentration in fruits increases greatly, cucumbers begin to taste bitter. Most often this happens with a sharp change in temperature, prolonged cold snap, influx of cold water, or uneven watering. That is, it is always associated with extreme situations. Try to avoid them and, when plants find themselves in such conditions, feed them with calcium and potassium nitrate. Strengthen your plants' own immune system by spraying them with Zircon.
DISEASES AND PESTS
The main pest of cucumbers is the spider mite. When it colonizes a leaf, it sucks the juices out of it, so the leaf first brightens, then turns yellow, and then dies. Ticks are very small and are clearly visible only under a magnifying glass. They live on the underside of leaves. Spraying with the biological preparation "Fitoverm" (or "Iskra-bio") works well against them. These biological products are absorbed by the leaf and protect the plant from all sucking and gnawing pests for three weeks. You can use garlic infusion, but then spraying must be done on the underside of the leaves. Chemical poisons should not be used, since after treatment, cucumbers cannot be used for food for 20 days.
In the second half of summer, cucumbers may be attacked by BLACK MELOND APHID. You should also not use pesticides against it; it is better to use green soap, a solution of potassium permanganate, pine needles, garlic and other home remedies. The fact is that aphids have a very delicate body and even hot (45-53 degrees) water will kill the aphids, but will not harm the plant.
Pay attention to the leaves: if a light border appears on young leaves. there is a great threat of downy mildew, which develops quickly when there is too much humidity in the air and soil, especially in cold weather. On adult leaves, yellowish oily spots appear on the upper side, along the veins, on which there is a whitish-purple coating on the underside of the leaf. Oily spots begin to dry out, gradually covering the entire leaf blade. The process of infection and drying of the leaves goes very quickly, literally in a few days all the plants and open ground, and especially in the greenhouse, look as if it is deep autumn. Naturally, there can be no talk of any fruiting. At the first signs of disease, stop watering, ventilate the greenhouses well, completely cover the soil under the cucumbers with ash or chalk to dry it, leaves with oily spots and dried ones should be removed and burned. Spray healthy leaves with “Fitosporin” or a solution of potassium permanganate hot pink color to prevent them from becoming infected. This same disease is sometimes called peronospora.
The most common disease of cucumbers in greenhouses is BACTERIOSIS. Angular yellow spots first appear on the leaves, which then dry out and crumble. Muddy pinkish droplets of liquid are visible on the underside of the leaf. The same cloudy droplets appear on fruit sores. In humid weather, the disease intensifies sharply. Constantly ventilate greenhouses at the first signs of the disease. Reduce watering, feed the cucumbers with an infusion of fresh manure or weeds, and give additional potassium fertilizer. Spray diseased plants with “Fitosporin”, “Zircon” or garlic infusion (200 g of chopped leaves and garlic arrows, pour 5 liters of water, cover, leave for 4 hours and immediately spray the leaves from below).
Another fairly common disease is ANTHracnose. It usually appears after bacteriosis. The disease first appears on the leaves - rounded spots form on them. brown spots, which are then painted over. Then anthracnose spreads to young green plants. Deep round ulcers with a hard edge appear on the fruits, reminiscent of bird pecks.
Spraying should be done with “Fitosporin”, “Zircon” or potassium permanganate, followed by pollination of wet leaves with ash, or even better - with dry mustard (only after potassium permanganate).
If the stems or leaf petioles become soft and covered with a white coating, then the cucumbers have developed WHITE ROT. High humidity with sudden changes in temperature, prolonged cold spells, watering with cold water, and stagnant air during dense plantings contribute to the appearance of the disease. URGENTLY do foliar feeding: 1 teaspoon of urea, a grain of copper sulfate (or HOM on the tip of a knife) per 10 liters of water. Stop watering, ventilate greenhouses, remove diseased fruits and leaves. Remove the plaque with a dry cloth or a cloth soaked in a raspberry solution of potassium permanganate, then pollinate the plants with ash or cover with a putty of chalk and potassium permanganate with water. The putty should be pink. Do not delay removing plaque, otherwise the plant will die!
Sometimes the whole plant wilts. This could be caused either viral disease- WILT (and then the plant should be removed so that sucking insects cannot transfer the disease to others), or ROOT ROT. In any case, you must first carefully rake the soil from the roots. If the root collar is soaked, it has Brown color, rotted, then this is root rot. Root rot often occurs where manure is used as biofuel. The top layer of soil around the plant must be completely removed. Water the roots with a solution of raspberry-colored potassium permanganate to kill the fungus in the soil. Remove the stem from the vertical trellis, lower the lower end onto the soil in a ring and tie it to the trellis again. Sprinkle the stem ring lying on the soil with fresh nutritious soil on top, moisten it well and make sure that it does not dry out. New roots will appear on the buried part of the stem.
If the dug up roots have a completely normal appearance, and the plant wilts, then it is WILT (verticillium wilt).