Why white spots appear on cucumber leaves and what to do to save the harvest

White spots on the leaves indicate that the plant is infected with pests or parasites. Such symptoms can be observed when growing cucumbers in a greenhouse and in open ground. Before removing stains, you need to find out why the plaque appeared and choose the right treatment.

Reasons for the appearance of white spots on cucumber leaves

Specialists highlight a list of diseases that are characterized by the appearance of white spots on cucumber leaves. Most often, plants grown in a greenhouse or greenhouse are covered with a white coating. Identifying the cause of this pathology begins with examining the bush. Spots on the leaves and stems of cucumber may indicate the presence of diseases.

Anthracnose

The causes of infection are fungal microorganisms Colletotrichum. They reach healthy plants with the help of wind, insects, and through unharvested plant debris from last season. Cucumbers can suffer from anthracnose throughout the growing season. Symptoms appear on leaves, stems and fruits.

Young plants are more susceptible to infection anthracnose, their stems are covered with brown depressed spots. The affected areas become thinner and break.

At the very beginning of infection, the leaves lighten and become covered with white spots, which over time acquire a brown tint. In open ground, the affected leaves dry out and begin to rot in the greenhouse.

Elongated brown spots appear on the fruits, this is how fungal spores penetrate inside. Cucumbers darken, become bitter, and rot.

Attention! Anthracnose spreads quickly and leads to reduced yields. Untimely treatment can lead to 100% crop loss. The disease is transmitted to other plants in the neighborhood.

The causes of the disease can be contaminated seeds, plant debris, and fungus., which is preserved on the walls of the greenhouse. Comfortable conditions for the development of the disease are high humidity and high temperature. Therefore, anthracnose most often affects plants in greenhouses covered with film.

Ascochyta blight

This is the infection of seeds with fungal spores, which slow down the growth of cucumbers.. Most often, greenhouse plants suffer from such microorganisms at the very beginning of summer. Lack of heat and microelements leads to a decrease in plant immunity. The disease develops on weakened specimens. Mycelium (mycelium) is not afraid of low temperatures. It appears during the fruiting period, in rare cases - during the formation of the stem.

First, the spores penetrate the seeds of the crop and begin to infect the upper tissues of the cucumber after planting in the soil. The vascular system does not suffer, so the plant continues to grow, albeit weaker.

During the appearance of leaves, the fungus increases its population and begins to infect tissues and blood vessels. The disease moves higher up the stem, microorganisms infect other leaves.

With the appearance of cucumbers, the mycelium penetrates into the fruit: White spots appear on them, which begin to rot over time.

Microorganisms can reproduce sexually and asexually, so they attack all weak cucumbers that grow nearby. The disease can be recognized; it is necessary to carefully examine the first leaves: the edges of infected leaves turn yellow and dry out.

White mosaic

This is a viral disease that lives in the soil and remains viable for more than 10 years.. It affects cucumber tissue at the cellular level and leads to the destruction of chlorophyll. The virus inhibits the process of photosynthesis, which is why the plant cannot receive nutrients and dies.

White mosaic affects the plant at any stage of development. Diseased seedlings grow poorly and do not take root after transplanting into the ground.

Infected cucumber leaves become covered with yellow spots near the veins. As the disease progresses, the spots increase in size and merge. The plant stops growing, the leaves turn yellow and dry out.

If the disease appears during fruit ripening, some flowers die, and lumpiness appears on the surface of the cucumbers. Such fruits are suitable for consumption; the virus itself does not cause any harm to humans, but the plant may die within 2 weeks after infection.

Powdery mildew

For powdery mildew cucumbers are covered with a white coating that resembles flour. Over time, the spores infect the entire leaf, after which it withers and turns yellow. The leaves that are closest to the ground are the first to suffer. If not treated in a timely manner, the disease spreads, rising to the top and infecting the upper leaves, flowers and even fruits. The plant may die completely or significantly slow down in development.

The disease most often appears in early summerwhen the temperature is low and the humidity is high. Such an environment is most comfortable for reproduction by spores.

Causes of plant infection with powdery mildew:

• improper watering - using cold water at low air temperatures;
• lack of lighting in the greenhouse;
• draft;
• deficiency of essential microelements or excess of nitrogen fertilizers;
• violation of crop rotation - growing cucumbers in one area for several years in a row.

Spider mite

Lives in the soil and on plants, worsening the quality of growth and quantity of harvest. Ticks Overwinter on the walls of greenhouses, in the soil and fallen leaves. When the soil warms up, pests crawl out of the soil and attack young plants.

The main causes of ticks – high temperature and dry air. The insect can get onto cucumbers from other plants in the neighborhood in a gust of wind or by catching on clothing or on a watering can when watering.

Attention! Spider mites can infect cucumbers with gray rot spores.

The danger is that the tick feeds on sap from plant cells. The surface of infected leaves becomes covered with white spots and dense cobwebs. The plant loses nutrients and cannot resist infections.

What to do to save the harvest

By detecting the disease in time, you can save the crop. If the affected area is small, the infected leaves are removed and healthy ones are treated with a soap solution. But if parasites have damaged most of the plants, chemicals are used.

In the greenhouse

The humidity level is high, and for many parasites this environment is ideal for reproduction. Treatment for parasites in greenhouse conditions begins with ventilation. Watering is stopped for 1 week. When the humidity level decreases, cucumbers are treated with folk remedies:

• 1 liter of liquefied cow manure is mixed with water (25 liters) and add tbsp. l. urea, solution suitable for irrigation of leaves;
• spraying with a solution of potassium permanganate and copper sulfate helps in eliminating many diseases that develop due to fungi.

If the use of folk remedies does not produce results, plants are treated with chemicals - “Fundazol”, “Topaz”.

Important! Before use, be sure to read the instructions - some chemicals cannot be used in the greenhouse.

Check all plants if symptoms of disease appear., growing in the neighborhood. If the diseased bush cannot be saved, it is dug up and destroyed.

In the open ground

Infection most often occurs through soil or air. Treatment of diseases in the garden is identical to treatment in greenhouse conditions.

A diseased bush should not be watered for 4-5 days.. It is recommended to loosen the soil to normalize air flow and prevent root rot. In order for cucumbers to get stronger and be able to fight diseases, they need strong immunity. To do this, fertilize with fertilizers 5-6 times per season.

Severely damaged plants can be cured using chemicals. In open ground, the use of the drugs “Fundazol”, “Topaz” and “Zaslon” is allowed. To spray plants, 1 ampoule is diluted in 8 liters of water. It is recommended to apply chemicals in the evening so that they do not evaporate under the sun.

Attention! Because the disease spreads quickly, act quickly.

Prevention measures

Cucumber diseases are easier to prevent than to deal with their consequences. Prevention starts with the right soil preparation and greenhouses. To do this, in the fall, all plants are removed by the roots and burned. The soil is dug up and the holes are watered with a solution of potassium permanganate. The greenhouse is ventilated for 2-3 days.

It is recommended to treat the seeds before sowing. To do this, they are soaked in a solution of copper sulfate or potassium permanganate. Young shoots should be protected from temperature changes and watered properly.Weeding should be done regularly, as many pests spread through weeds.

Compliance with crop rotation – an important method for preventing diseases of cucumbers. The land on which cucumbers grew last season is not suitable for replanting, so this area should be used for cucumbers after 3-4 years.

To prevent viral diseases It is recommended to water the plant with a solution of copper sulfate mixed with ash. The presence of ash in the soil will protect the plant from many other pathogens.

Useful tips from experienced farmers

Every farmer uses his secrets to get a rich harvest. Tips from experienced gardeners will help you grow healthy cucumbers:

1. From the beginning of July, it is recommended to treat cucumbers with onion peel. To prepare 10 liters of boiling water, take 0.7 liters of onion peels, bring to a boil and leave for 24 hours. Dilute the resulting mixture with water in a ratio of 1:4. Spray the plant with the solution and water it 2-3 times a month.
2. During the flowering period, water the cucumbers with a mixture prepared from 2 liters of whey and 150 g of sugar.
3. To eliminate pests during growth, use a solution of iodine and laundry soap. To do this, dilute 30 drops of iodine in 10 liters of water, add 20 g of laundry soap and, if desired, 1 liter of milk. Spray once every 10 days.

Conclusion

Cucumbers are an unpretentious plant that grows well in open ground and greenhouse conditions. However, this crop is susceptible to pests and parasites. Prevention and timely treatment will help prevent the consequences of diseases and enjoy a rich harvest.