Many gardeners dream of getting a bountiful harvest of vegetables every year, but white spots on the leaves of cucumbers threaten the death of most plants. The presence of plaque indicates the appearance of diseases or pests on plants. The sooner the problem is identified and treatment is started, the higher the likelihood of saving the harvest.
Experts identify a number of diseases that are characterized by a white coating on plant leaves. The most common disease found in summer cottages is powdery mildew and mosaic.White spots on cucumber leaves indicate spider mite infestation.
Powdery mildew
A white coating on the leaves of cucumbers indicates that the plant is infected with powdery mildew. It appears first at the edges of the leaf blade, gradually covering the entire area. Then the disease spreads to the shoots and stems. A characteristic symptom is not only spots, but also a light-colored fluffy coating.
Infection of plants begins from the top of the face plate. The disease may appear on bushes located closer to open windows. If there is no fight against the disease, the bush begins to wither and the harvest is completely lost.
Reasons for appearance
If we talk about what causes powdery mildew, then pay attention to the conditions under which the cucumbers are kept. The prerequisites for the appearance of the disease in a greenhouse are:
- coolness and high humidity;
- increased density of plantings;
- increased nitrogen content in the soil;
- overdrying of the soil followed by overwatering of plants;
- excessive watering of plants;
Fighting methods
Powdery mildew responds well to treatment. When the first signs of plant damage appear, you need to start fighting it.
To cure powdery mildew you need:
- stop all types of spraying;
- eliminate the application of fertilizers;
- improve lighting in the greenhouse;
- thin out plantings;
- remove affected, old or weakened leaves;
- cut off flower stalks.
Treating plants with antiseptic compounds can directly combat stains. Chemical antifungal drugs and folk remedies are used in garden plots.
- Topaz. An antiviral drug with the active substance penconazole. To prepare the solution, use 1 ampoule per 10 liters of water.Plants are treated every two weeks until plaque stops appearing.
- Emulsion Tilt CE. An effective drug based on propiconazole. Is dangerous for bees and fish. Suitable for combating plaque and disease spores. Most effective at elevated temperatures.
In addition to Topaz and Emulsion, Sulfarid, Bayleton, Skor, Vitaros showed high efficiency. In the early stages, Bordeaux mixture and oxychloride are suitable for control. A folk remedy that helps remove powdery mildew is a soap-soda solution. What to do and what control methods to choose directly depends on the degree of damage and the spread of the disease.
White mosaic
White or cucumber mosaic is a viral disease. Cucumbers, tomatoes, cabbage and other vegetable crops are susceptible to it. The main development of the disease occurs in living plant cells. But the virus can be transmitted through a dry leaf. It persists in the soil and on equipment for a long time.
Features of manifestation
Cucumber mosaic falling onto a leaf healthy plant, leads to the destruction of chlorophylls. As a result, the level of carbohydrates in the plant decreases. Characteristic symptoms of white mosaic are light spots that initially have unclear contours. Their localization occurs in the vein area.
Gradually the spots increase in size. Cucumber leaves turn completely white or yellow. Plant growth is suppressed and productivity decreases.
White mosaic is a greenhouse problem. The reasons for its appearance include:
- high density of plantings;
- increased room temperature;
- sharp fluctuations in air temperature.
The disease often appears on cucumber seedlings that have just been transplanted into the ground.Young leaves and shoots of the plant are also susceptible to damage.
Fighting methods
If many white spots and signs of mosaic damage appear on the leaves of cucumbers, then it is necessary to begin the fight against the virus as early as possible. It should be understood that plant treatment is ineffective.
To cure the disease and prevent its occurrence, a number of rules must be followed.
- Normalization of temperature. In the room where the cucumbers are located, the temperature should be reduced and temperature changes should be avoided. Optimal conditions are temperatures below 30 degrees.
- Removing affected leaves. It is necessary to remove all leaves on which white spots appear. In some cases, entire cucumbers are removed.
- Inventory processing. All equipment with which the cucumbers came into contact must be treated with boiling water, an antiseptic solution or alcohol.
- Reducing planting density. Cucumbers should be thinned out and given more air and space.
To prevent the appearance of white spots on cucumbers is to use mosaic-resistant varieties, regularly weed the greenhouse and clean the room, and use only high-quality seeds for sowing seedlings.
Spider mite
Cucumbers grown in open ground are susceptible to spider mite infestation. It feeds on plant sap and causes the green mass to dry out. The cucumbers grow small and deformed. If you do not treat plants against the parasite in time, you can lose the harvest completely.
Features of manifestation
About the appearance spider mites on cucumbers indicates the presence of a number of signs:
- light dots on the leaf plate;
- a thin web on the back surface of the leaf;
- slowing down plant growth;
- yellowing of green mass.
Fighting methods
It is easier to prevent an emerging disease than to fight it when it has affected adult plants. As prevention methods before planting cucumbers, the following is carried out:
- digging up the soil;
- weed removal;
- alternation of planted crops.
If the leaf on the cucumbers turns white and signs of a mite appear, then it is necessary to treat the plants and carry out preventive work. To do this, all dry and infected leaves are removed and burned. The humidity in the greenhouse is increased to 70-80%. The tick does not tolerate humidity above 60%.
Disinfection with chemicals can completely cure the disease. The following have shown high effectiveness in the fight against ticks:
- Aktellik;
- Apollo;
- Neoron;
- Karbofos;
- Sunmite;
- Fitoverm.
Most drugs have a wide spectrum of action and belong to the budget category. If you are fighting diseases with traditional methods, then the following are considered effective:
- soap solution;
- garlic;
- alcohol solution;
- onion solution;
- decoction of Caucasian hogweed.
The fight against ticks should begin as soon as the first signs of damage are detected. If its spread is not prevented in the initial stages, all plants will become covered with white dots.
Ascochyta blight
White spots on cucumbers in a greenhouse may result from infection with ascochyta blight. The disease affects weakened bushes. The fungus is transmitted through the soil or carried in organic debris.
Features of manifestation
The disease appears as white or brown spots along the edges of the plant. Gradually the entire leaf becomes covered with spots. The affected area dries out. As a result of infection by the fungus, the cucumber stops growing. The appearance of copper exudate is noted on the stems.
A mutation occurs in the fruit. They become covered with black dots, resemble cooked vegetables, and are completely unsuitable for consumption.The disease is most active during the fruiting period.
If you understand why ascochyta blight appears on cucumber leaves, gardeners identify a number of reasons:
- weak plants;
- high indoor humidity;
- presence of fungus in the soil;
- non-compliance with crop rotation in the garden plot.
Fighting methods
White plaque on cucumbers can be prevented if you follow the rules for combating and preventing ascochyta blight.
- Cultural turnover. It is necessary to regularly change the places where crops are planted on the ridges.
- Mulching. To prevent the leaves from becoming stained, the surface of the soil after planting is covered with mulch or plastic film.
- Use of resistant varieties. The use of fungus-resistant varieties can prevent the development of ascochyta blight.
- Sowing sanitary crops on the site. Sowing green manure (rye, oats) allows for comprehensive soil sanitation.
- Antiseptic treatment. If the leaves become stained, then it is necessary to remove the affected areas and treat the plants with antiseptic solutions. Spraying with Bordeaux mixture or coating the stems with copper-chalk powder showed high effectiveness.
Most often, spots appear on the leaves of cucumbers in a greenhouse. This is due to increased temperature and humidity in the room. When choosing what to treat, it is necessary to rely not only on the experience of gardeners, but also on the type of disease that has affected the plants. Timely prevention and proper care of plantings can also prevent infection.
