The main reasons why cucumber leaves turn white
If the cucumber leaves are covered with a white coating, then the first step is to understand the reasons for its occurrence.
Lack of light
Sometimes the cause of whitening of leaves can be insufficient lighting. Most often the problem occurs when grown in a greenhouse, but it can also occur in an open area. It should be borne in mind that whitening of the lower leaves on cucumber bushes is the absolute norm, since due to their density, they do not receive enough sunlight. You need to worry when the entire plant is covered with white spots.
Improper watering
The cause of the white coating on cucumber leaves may also be improper watering. Moreover, both excess and lack of moisture can be detrimental to the plant. The leaves are always the first to suffer, especially in open ground plantings, where it is more difficult to control the level of humidity. If the summer is rainy, the cucumber leaves will most likely turn white, and the roots will soon be damaged.
Insufficient moisture causes the leaves to turn white and begin to dry out quickly. However, getting rid of this problem is not difficult; you just need to water the bushes more often.
Lack of nutrients
The cause of white spots may be a lack of essential nutrients. This problem is typical for cucumbers grown both in greenhouse conditions and in open ground.
If the bushes begin to turn white from the bottom up - from the root, then the reason for this is most likely a lack of magnesium and potassium. In this case, it is urgent to add fertilizer rich in these microelements to the soil.
If dark veins on the stems and leaves are added to the main symptom, then the problem is an insufficient amount of iron and manganese. The main “symptom” of copper deficiency is the whitening of leaves from top to bottom.
Disembarkation time
Unlike tomatoes, cucumbers are extremely sensitive to planting. Any mistake at this stage may result in the plant not taking root. Incorrect disembarkation times are especially detrimental. Dates vary depending on regions, so their choice must be approached with special responsibility. Early planting is a common cause of leaves turning white.
In greenhouses, the soil warms up faster, so you can plant cucumbers several weeks earlier than the recommended time.
Soil acidity
Each vegetable crop has certain growing conditions. What is good for some plants can be detrimental to others. The optimal soil acidity level for cucumbers is 7 pH; any value below this level is potentially harmful to the cucumber crop. Increased acidity inhibits the development and growth of plants and complicates the absorption of nutrients. This leads to whitening of the leaves.
Aging
All living organisms on the planet age sooner or later; for plants this means a slowdown in photosynthesis and gradual whitening and wilting. Aging is an inevitable process. But it is worth considering that natural senescence for plants occurs only after harvesting; if the process began earlier, then the reason for this is some kind of disease.
Rules for processing bushes
There are certain rules for processing vegetable crops that should be followed in order to completely end the problem.
In greenhouses and greenhouses
It is important that whatever is left of the plants is destroyed. It is also worth spraying for preventive purposes, even if there are no traces of parasites or diseases
In the open ground
If the crop is grown in open ground, any manipulations should be carried out in suitable weather. The day should be calm so that the preparations remain on the plant as long as possible. Just as in a greenhouse, all affected bushes must be removed from the beds and destroyed.
Diseases and pests
Of course, whitening of leaves can be a symptom of a plant disease. Quite a few diseases to which cucumbers are susceptible are characterized by the appearance of a white coating, but the nature of the spread will vary.
White mosaic
The virus takes effect when sudden changes in temperature occur. The first signs of the disease appear a month after planting. If the cucumber leaves curl at the edges, wrinkle characteristically, cracks appear on the stem, and spots appear on the fruits, then the white mosaic has completely affected the plant.
Causes of the disease:
- shaping, picking cucumbers with an infected tool;
- infection through insects.
The only thing that can be done in this case is to disinfect the tools in advance; if the disease has already penetrated the plant, then it cannot be saved.
Powdery mildew
This is a fungal disease. Characteristic of this virus is the damage to leaves by a white coating that appears along the edges of the plate. Over time, it moves first to the center of the leaf, then to the stems, ovaries and roots. The first sign of infection with this disease is the appearance of a white rash on the leaf. The spots soon turn black, the edges of the leaves dry out, as a result of which the plant begins to die.
The causes of infection may be:
- excessive amounts of nitrogen fertilizers;
- error in the irrigation system.
The fungal pathogen can survive the winter on the remains of a dead plant. The disease takes effect in gloomy, damp weather.
Spider mite
Small white spots appear first on the leaves, then on the stems and ovaries. The edges of the sheets curl and dry out over time. These signs are a sure sign that the plant is infected with a parasite. The mite that provokes this disease settles at the bottom of the leaf, where it gradually entwines the plate with a web and sucks out the nutritious juices. It is impossible to notice this mite with the naked eye.
Greenhouse whitefly
A fungus that makes holes in the leaves through which it sucks out the juices. The main symptom is a sugar-like discharge on the leaves containing fungal spores. After defeat, cucumbers quickly dry out and die.
Ascochyta blight
A fungal disease that affects many vegetable and cereal crops. The main symptoms: spots of different shapes, shades and sizes, which have a dark border. Soon, brown dots appear on top of the initial light marks, which contain the fruiting bodies of the fungal disease. The plant cannot be saved, but the future harvest can be saved if you carefully destroy the remains of last year’s harvest, organize correct crop rotation and take only healthy seeds for planting.
Anthracnose
A common fungal disease affecting almost all leaf crops. The most common cause of infection is infection by mycelium, which can survive the winter in seeds or organic remains of dead plants. The disease is characterized by the formation of deep light and dark spots and ulcers. Over time, the affected areas provoke breaking of stems, destruction of leaf plates and rotting of the root system.
Preventive measures
Usually the leaves of cucumbers grown in greenhouses turn white and dry. This is facilitated by limited area, poor supply of fresh air, and lack of crop rotation. It is important to take measures before construction to prevent the development of pathogenic fungi and insects.
Greenhouse
The greenhouse design must have ventilating windows so that through ventilation is possible. The greenhouse itself should not be exposed to direct sunlight all day. If this condition is difficult to comply with, one side is covered with agrofibre. This is a special non-woven material with anti-ultraviolet treatment.
Another point in building a greenhouse is strong protection from moisture during rain. Strong drops or streams of moisture can clog the soil and limit the oxygen supply to the roots.
Fungi
The struggle for harvest when exposed to spider mites is more difficult than in a situation with fungal diseases. The mite larva is resistant to unfavorable conditions, which is why it is so important to follow all preventive measures to avoid complete drying out of the plant.
- If possible, change the place where cucumbers are planted;
- maintain humidity 80-90%;
- inspect plants as often as possible to detect mites (especially the lower leaves);
- In the fall, carefully remove plant remains and prepare the soil in advance for the next planting season.
Other methods
Other protective measures include a number of actions:
- collect seeds only from healthy plants;
- disinfect greenhouse structures and soil;
- apply biological products and organic fertilizers.
The main thing is to identify and remove diseased plants in a timely manner. You can spray the place where cucumbers are planted with Bordeaux mixture preparations, copper oxychloride, and abiga-pink.
Why do the leaves of cucumber seedlings turn white?
The main reasons for this phenomenon are:
- sunburn if the seedlings were taken out of the room into the scorching sun without preparation;
- various diseases;
- lack or excess of moisture;
- damage to the root system during planting.
As a rule, the causes differ little from other cases, but the first signs occur much earlier.
How and with what to fight white leaves
After determining the cause of the appearance of white spots, you can proceed to treatment. It often happens that this is the result of agrotechnical mistakes by inexperienced agronomists. If the leaves turn white, then special preparations can help.
Quadris
The drug can not only help eliminate the disease, but also protect against repeated damage. It is better to treat the plant with this preparation in the evening or early morning, provided that there is no strong wind. One application is enough to destroy harmful substances.
It is recommended to use 100-200 ml of medicine per bush. It is best to treat the bush 3 times with an interval of 3-5 weeks.
Cuproxat
This medicine is good for treating white cucumber leaves. The drug was released specifically to protect plants from insects and various diseases. Kuproxat is sold in large containers, ready for use immediately after purchase. The optimal time for application is before planting cucumbers in the ground. It is much more effective to use the drug as a preventive measure.
Jet
If the cucumber leaves slowly begin to lighten immediately after planting, then the drug Jet can help. It is sold in powder form for preparing a solution. The drug in an amount of 100 grams should be mixed with 10 liters of water. Leave the solution for 20-40 minutes. The prepared drug cannot be stored for a long time; it is advisable to use the solution immediately after preparation.
Prevention methods
Infections of cucumbers in a greenhouse by fungal diseases can be prevented if you follow the rules of agricultural technology:
- Replace the top layer of soil in the greenhouse.
- Before planting cucumbers, treat the area with the biopreparation “Gamair” and add wood ash.
- For planting, choose varieties and hybrids that are resistant to crop diseases.
- Treat the seeds with Fitosporin-M, a pink solution of potassium permanganate.
- It is better to plant cucumbers if onions, garlic, legumes, and cabbage were previously grown in the greenhouse.
- Maintain the microclimate in the greenhouse, ensure air circulation.
- Thin out plants. In dense plantings, the roots do not receive enough nutrition, and air access to the plants is difficult.
- Water the bushes at the root, without using cold water.
- Timely fertilizing with phosphorus and potassium fertilizers.
- Regularly loosen the beds.
Folk remedies
Methods of combating white leaves of cucumbers were invented long before specialized drugs appeared. Traditional recipes may not be as effective in advanced stages of the disease, but they are less harmful.
Onion peel
Onions help prevent white spots on plant leaves. For the mixture, just mix 300 grams of onion peels with 5-7 liters of water. The finished solution is brought to a boil, then infused for 10 hours. You can not only spray the leaves with the medicinal infusion, but also water the plant.
Milk serum
If cucumber tops have been blanched, then whey with kefir will help best. A 10-liter container is filled with 7 liters of water and 3 liters of kefir whey. Sugar added in small quantities improves the effect of the remedy.
Baguette
This mixture is very easy to prepare. It is enough to soak a couple of loaves of bread in a large (at least 10 liters) container. Soaking time - 12 hours. At the last stage, add 10 liters of water and a spoonful of iodine to the resulting mixture. It is best to use the remedy twice a month, then a white coating on the cucumber leaves will never appear.
