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One of the most common vegetable diseases is peronosporosis of cucumbers. Treatment of this disease should be carried out immediately after its onset. If this is not done, then over time, the yield of cucumbers will decrease and the plant will die.
Small oily spots of yellow color form on the leaves of plants that suffer from downy mildew. They are limited to veins and have a rounded shape. Over time, the lower part of the leaves is covered with a purple bloom. Gradually, the spots on the leaves begin to grow and merge. Because of this, they dry out, wrinkle and crumble. After the leaves die off, the development and setting of cucumbers slows down, the fruits lose their former juiciness and rich taste. If untreated, downy mildew on cucumbers can completely destroy the plant within a short period of time.
Peronosporosis is a rather dangerous disease, as it can harm not only cucumbers, but also other cultivated plants. Shrubs, trees, vegetables and even houseplants can become infected. The spread of the disease is facilitated by various insect pests - aphids or whiteflies. Therefore, if these pests were noticed on cucumbers, you need to immediately take measures to eliminate them.
Reasons for the appearance
To infect a plant with downy mildew, there must be certain conditions - heat and high humidity. There are also other factors that contribute to its appearance and development:
- regularly watering cucumbers with too cold water;
- poor ventilation system in the greenhouse;
- strong temperature drops;
- lingering showers, due to which the humidity of the air rises;
- a large number of weeds near the plants.
In dry weather, peronosporosis appears very rarely in cucumbers. It quickly infects the plant only under favorable conditions. Quite often because of this, another disease of cucumbers appears - bacteriosis.
There are various ways to protect cucumbers from the appearance and spread of downy mildew.
There are several basic recommendations that will help prevent cucumber downy mildew:
- You need to plant seeds in places where it will be quite difficult to become infected with downy mildew. Planting should be carried out in areas with pre-treated soil.
- After collecting the fruits, it is necessary to disinfect the soil and get rid of plant residues.
- During the growing season, it is necessary to monitor soil moisture.
- It is recommended to cultivate varieties that are resistant to downy mildew. These include the Zodiac, Debut, Idol, Rodnichok and Photon.
- When cultivating cucumbers in a greenhouse, you need to monitor the microclimate in it in order to avoid the occurrence of drip moisture on the leaves.
- The soil should be regularly fertilized with organic and mineral substances, which increase the resistance of cucumbers to various diseases.
- If some bushes have already become infected with peronosporosis, then they should be immediately destroyed. This will prevent the disease from spreading to other plants.
The site must be regularly cleaned of fallen leaves, in which zoospores can develop. Also, the earth must be periodically disinfected and dug up to a depth of about 35-40 cm. If the bushes were infected in the previous year, then it is better to repeat the digging in the spring.
Disinfection of the soil is carried out using a 1% solution of potassium permanganate and 3% solution of copper sulfate. It is necessary to use these mixtures very carefully, as they can harm not only the pathogenic, but also beneficial microflora.
In the garden, it is imperative to observe the crop rotation. The culture can be returned to its original place only after 4-5 years. If you plant cucumbers in the same place for several seasons, then an accumulation of bacteria and infections can occur. This increases the likelihood of contracting downy mildew.
For cucumbers to be more resistant to disease, they need to be properly planted. Before planting, you should do the disinfection of the seeds. This can be done using heat treatment. For this, the seeds are warmed up to 35-40 ° C within 15-20 minutes. You can process the seedlings of cucumbers with a weak 0.1% solution of potassium permanganate. In this case, its roots are dipped into the mixture for several hours.
During the growing season, it is necessary to monitor the spread of weeds. You also need to regularly get rid of plants that can no longer be cured of powdery mildew. They should be dug up first and then burned.
Preparations for peronosporosis
Chemical preparations are quite effective means of combating peronosporosis.
Used to treat and prevent disease. The composition of Acrobat MC contains two active substances that belong to cinnamic acid amides - dimethomorph and mancozeb. They have a local systemic action that protects the cucumbers inside and out.
Before using the drug, it is necessary to prepare a working solution. To do this, add 50 g of Acrobat MC to 10 liters of water. The first treatment can be carried out even in the absence of signs of peronosporosis in cucumbers.
This will be an excellent prophylaxis to protect the bushes from disease. The second spraying should be carried out two to three weeks after the first.
It is better to do the treatment in clear and calm weather, so that the drug evenly falls on the bushes and is not sprayed on neighboring plants.
It can be used to treat downy mildew and other fungal diseases. It also reduces soil toxicity after using hazardous chemicals and restores soil microflora.
To prepare a working solution for watering bushes, two tablets of the drug are added to 10 liters of water. When spraying cucumbers, use a different mixture. For its preparation, one Alirin B tablet should be added to each liter of water.
This product has excellent compatibility with other products, so it can be used together with growth regulators, fungicides and insecticides.
It is used during the prevention of bacterial and fungal diseases. The active ingredient of the drug is the mushroom culture of Trichoderma. When this substance enters the cells of the disease, it begins to dissolve them from the inside. This blocks the further development and spread of peronospora.
Glyocladin is not used for spraying bushes, but for treating the soil before planting cucumbers. The preparation should be placed in the upper layers of the soil, since this is where the best conditions for trichoderma are. When planting seeds, no more than two Glyocladin tablets should be added to the hole. It is recommended to use gloves while working with the preparation.
This systemic contact fungicide is excellent for protecting cucumbers against LMR. It destroys pathogens in all stages in the shortest possible time. Oxychom contains copper oxychloride, which kills all vital components of the cells of peronosporosis.
To prepare a working solution in 5 liters of water, add 15 g of the drug. The mixture should be applied to bushes in sunny and calm weather. You need to spray cucumber bushes at least three times per season. The interval between treatments is about 10-15 days.
Oxyhom cannot be used in parallel with other agents that should not come into contact with an alkaline environment.
The drug is available in powder form, which can be sold in packages weighing from 1 to 10 kg. The composition of this tool includes two active substances with which you can get rid of peronosporosis:
- cymoxanil - it slows down the synthesis of ribonucleic acids;
- copper oxychloride - disrupts the performance of the enzymatic system.
When processing cucumbers, it is recommended to use a 0.025% solution. To prepare it, add 25 g of the drug to 10 liters of water. You need to spray the bushes immediately after the first symptoms appear. It is impossible to store the working solution for a long time, as it quickly deteriorates.
Ordan is not recommended for use with drugs that contain alkalis. It can be combined with other fungicides and pesticides. However, they must be checked for compatibility before mixing. If they are not compatible, then a precipitate will appear in the solution.
When spraying the bushes, this agent gets on the leaf plate and protects it from pathogens. The main active substance of Quadris is azoxystrobin, with the help of which infectious agents are destroyed.
It is recommended to use 0.2% or 0.1% working solution for processing. In one season, you need to spray the bushes at least three times. It is necessary to do this in the evening or morning, when there is no strong wind.
In addition to the use of chemicals, there are other measures to combat downy mildew on cucumbers. You can get rid of this disease in cucumbers with various folk remedies.
To prepare a soda solution, you need to add 40 g of soda and 15 ml of liquid soap to 5 liters of boiled water. All components should be thoroughly mixed until they are completely dissolved. After that, you can start spraying the soil and bushes. The procedure must be carried out 4 times per season. The interval between treatments should be about one week.
To prepare a milk solution, 40 drops of iodine and 35 g of grated laundry soap are added to a liter of milk. You need to use this tool throughout the entire growth period of cucumbers. Spraying should be carried out regularly, every 10 days.
You can also make whey. To do this, several liters of milk are added to a bucket of water, after which the mixture is heated to a temperature of +25 degrees. Serum can be used not only to treat already infected bushes, but also healthy ones.
This medicine is very effective in the early stages of the disease. For its preparation, 500 g of husks are added to 10 liters of water. The resulting mixture is boiled over low heat and infused for several days. It is recommended to spray cucumbers several times a month.
Peronosporosis is a rather dangerous disease that can lead to the death of plants. You need to get rid of downy mildew on cucumbers immediately. To do this, it is enough to get acquainted with the most effective ways of dealing with it.