Why did white spots appear on the leaves of cucumbers, what to do and how to treat
Many gardeners dream of getting a bountiful harvest of vegetables every year, but white spots on cucumber leaves threaten the death of most plants. The presence of plaque indicates the appearance of diseases or pests on the plants. The sooner the problem is identified and treatment is started, the higher the chances of saving the crop.
Experts identify a number of diseases that are characterized by a white bloom on the leaves of plants. The most common disease in suburban areas is powdery mildew, mosaic. On the leaves of cucumbers, white spots indicate a spider mite infection.
Powdery mildew
White bloom on the leaves of cucumbers indicates a plant infection with powdery mildew. It appears first at the edges of the leaf plate, gradually covering the entire area. Then the disease spreads to shoots and stems. A characteristic symptom is not only specks, but also a fluffy bloom of light color.
Plant infection starts from the top of the faceplate. The disease can appear on bushes located closer to the open vents. In the absence of a fight against the disease, the bush begins to wither, the harvest completely disappears.
Reasons for the appearance
If we talk about what powdery mildew can appear from, then they pay attention to the conditions for keeping cucumbers. The prerequisites for the appearance of a disease in a greenhouse are:
- coolness and high humidity;
- increased plant density;
- increased nitrogen content in the soil;
- overdrying of the soil with subsequent overflow of plants;
- excessive watering of plants;
Control methods
Powdery mildew responds well to treatment. When the first signs of plant damage appear, it is necessary to begin to deal with it.
To cure powdery mildew you need:
- stop all types of spraying;
- exclude fertilization;
- improve lighting in the greenhouse;
- thin out plantings;
- remove diseased, old or weakened leaves;
- cut off the peduncles.
Treatment of plants with antiseptic compounds allows you to fight directly with spots. In garden plots, chemical antifungal drugs and folk remedies are used.
- Topaz. Antiviral drug with an active substance - penconazole. To prepare the solution, 1 ampoule is used per 10 liters of water. Plants are processed every two weeks, until plaque stops appearing.
- Emulsion Tilt CE. An effective drug based on propiconazole. 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 liquid and oxychloride are suitable for the fight. With folk remedies, a soap-soda solution helps to remove powdery mildew. What to do and what methods of struggle 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 vegetables are susceptible to it. The main development of the disease occurs in the living cells of the plant. But the virus can be transmitted through a dry leaf. It persists in soil and inventory for a long time.
Features of manifestation
Cucumber mosaic falling on the leaf healthy plant, leads to the destruction of chlorophylls. As a result, the level of carbohydrates in the plant decreases. The characteristic symptoms of white mosaic are light spots, which at first have indistinct contours. Their localization occurs in the vein area.
The spots gradually increase in size. Cucumber leaves turn completely white or yellow. Plant growth is suppressed, yield 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 affected.
Control methods
If many white spots and signs of mosaic damage appear on the leaves of cucumbers, then it is necessary to start the fight against the virus as early as possible. It should be understood that the treatment of plants is ineffective.
To cure the disease and prevent its appearance, a number of rules should be followed.
- Normalization of temperature conditions. In the room where the cucumbers are located, the temperature should be reduced and its drops should be excluded. The optimal conditions are temperatures below 30 degrees.
- Removal of diseased leaves. It is necessary to remove all leaves on which white spots appear. In some cases, the whole cucumbers are removed.
- Inventory handling. All inventory that the cucumbers came into contact with must be treated with boiling water, an antiseptic solution or alcohol.
- Reduced plant density. The cucumbers should be thinned out and given more air and space.
Prevention of the appearance of white spots on cucumbers is the use of varieties that are resistant to mosaic, regular weeding of the greenhouse and cleaning the premises, using only high-quality seeds for sowing seedlings.
Spider mite
Outdoor cucumbers are susceptible to spider mite infestations. It feeds on plant sap and causes the green mass to dry out. Cucumbers grow small, deformed. If you do not treat the plants from the parasite in time, you can completely lose the crop.
Features of manifestation
About the appearance spider mites on cucumbers says the presence of a number of signs:
- light points on the sheet plate;
- thin cobweb on the back of the leaf;
- slowdown in plant growth;
- yellowing of green mass.
Control methods
An emerging disease is easier to prevent than to fight when it affects adult plants. As methods of prevention, before planting cucumbers, they carry out:
- digging up the soil;
- weed removal;
- alternation of planted crops.
If the leaf on the cucumbers turns white and signs of a tick appear, then it is necessary to process 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 mite does not tolerate moisture above 60%.
Disinfection with chemical preparations allows to completely cure the disease. High efficiency in the fight against mites was shown by:
- Actellik;
- Appolo;
- Neoron;
- Karbofos;
- Sunmight;
- Fitoverm.
Most drugs have a wide range of effects and belong to the budget category. If you are fighting diseases with folk methods, then the following are considered effective:
- soap solution;
- garlic;
- alcohol solution;
- onion solution;
- a decoction of the Caucasian hogweed.
The fight against the tick should be started as soon as the first signs of damage are found. If its spread is not prevented in the initial stages, all plants will be covered with white dots.
Ascochitosis
White spots on cucumbers in the greenhouse can result from infection with ascochitis. The disease affects weakened bushes. The fungus is transmitted through soil or carried in organic debris.
Features of manifestation
The disease manifests itself as white or brown spots around the edges of the plant. Gradually, the entire leaf becomes covered with spots. The affected area dries up. As a result of a fungal attack, the cucumber stops growing. The appearance of copper exudate is noted on the stems.
Fruit mutation occurs. They are covered with black dots, resemble cooked vegetables, and are completely unsuitable for human consumption. The disease manifests itself most actively during the fruiting period.
If you understand why ascochitosis appears on the leaves of cucumbers, then gardeners distinguish a number of reasons:
- weak plants;
- high humidity in the room;
- the presence of fungus in the soil;
- non-observance of culture rotation in the garden.
Control methods
White bloom on cucumbers can be prevented if you follow the rules for combating and preventing ascochitis.
- Culture turnover. It is necessary to regularly change the places of planting crops on the ridges.
- Mulching. To prevent the leaves from becoming stained, the surface of the soil after planting is covered with mulch or plastic wrap.
- The use of resistant varieties. The use of varieties resistant to the fungus allows to prevent the development of ascochitis.
- Sowing on the site of sanitary crops. Sowing siderates (rye, oats) allows for complex soil treatment.
- Antiseptic treatment. If the leaves are stained, then it is necessary to remove the affected areas and treat the plants with antiseptic solutions. Spraying with Bordeaux liquid or coating the stems with copper-chalk powder has shown high efficiency.
Most often, spots appear on the leaves of cucumbers in the greenhouse. This is due to the 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 affected the plants. Also, timely prevention and competent planting care allows to prevent infection.
