Powdery mildew (ashtray) is a plant disease caused by microscopic fungi, often causing damage to greenhouse cucumber crops and open ground. The fungus responsible for infecting this particular crop is Oidium erysiphoides. The mycelium usually develops in June, first affecting the leaves, then the stems and fruits. Timely treatment and preventive measures help preserve the harvest and collect fruits.
The causative agent of the disease
Powdery mildew is a dangerous disease characteristic of cucumbers. The urgency of the fight lies in the fact that the infection develops quickly and is transferred from bush to bush, while the yield drops by 40-50%.
On a note! The pathogenic fungus that provokes the development of powdery mildew can live dormant in the soil for up to 6 years.
The causative agents of the disease are powdery mildew fungi, which belong to the group of obligate parasites.
The most common 3 types of powdery mildew pathogens are:
- Erysiphe cichoracearum. A common pathogen that is more common in northern regions.
- Podosphaera fuliginea. A fungus that is most often found in the southern regions.
- Levelula taurici. Of the listed pathogens of powdery mildew, this species is the least common. Characteristic of Central Asian and southern CIS republics.
Fungal spores quickly settle in epithelial cells and spread throughout the above-ground part of the plant. Mycelium (white coating) is formed, which appears on all parts of the cucumber vine (stems, leaves, vegetables).
Varieties resistant to downy mildew
Thanks to successful breeding work, varieties have been developed that demonstrate resistance to downy mildew. These include:
- Early ripening variety "Boy Thumb". It tolerates dew and other unfavorable factors well. The first greens can be picked 37 days after germination of the seedlings.
- Resistance to downy mildew is demonstrated by the Pasadena variety. It is also able to resist some other diseases. It belongs to the group of mid-early varieties. Fruiting begins 45 days after the sprouts appear.
- The Octopus hybrid is not susceptible to infection with peronospora, olive spot and mosaic viruses. It can grow in a greenhouse or open ground. Fruiting begins 45 days after germination.
- The high-yielding variety “Golubchik” ripens 55 days after germination. It is not susceptible to peronosporosis and has an excellent taste.
- The “Nonashka” variety is resistant to true and downy mildew and root rot. After the sprouts appear, it is ready for harvest on the 43rd day. These cucumbers can grow in open ground or in a greenhouse.
The presented varieties resist downy mildew well, but are not completely protected from this disease. Downy mildew is dangerous for many varieties of this crop. Therefore, it is recommended to follow preventive measures to protect yourself.
Downy mildew is a dangerous, rapidly spreading disease. It can destroy an entire crop of cucumbers in a matter of days.
Therefore, when growing this crop, it is important to follow all the rules of agricultural technology and plant varieties that have increased resistance to the disease.
Conditions for the occurrence of the disease
The first symptoms of powdery mildew often occur at the beginning of the summer season. During this period, favorable conditions are observed for the development of fungus and the spread of spores (high humidity and optimal temperature conditions).
Favorable indicators for the development and reproduction of the fungus are:
- humidity level more than 50%;
- temperature value is 20-27 oC.
To protect cucumber plantings from a dangerous fungal disease, eliminate the main causes that provoke its appearance:
- crop rotation rules are not followed;
- lack of phosphorus and potassium in the soil;
- excess nitrogen;
- watering with cold water;
- insufficient lighting in the greenhouse and constant drafts;
- temperature changes and long periods of inclement weather.
On a note! Inspection of cucumber plantings is carried out every 3-4 days, since symptoms appear during this period.
Symptoms of powdery mildew
It is easy to recognize the appearance of the powdery mildew pathogen on cucumber leaves by the white coating. At first glance, it may seem that flour has been scattered throughout the greenhouse.
Initially, a white coating, similar to blotches, appears on all vegetative parts of the plant - leaves, stems, flowers. If left untreated, the fungus forms in all green areas of the crop, which leads to gradual drying out. White spots may change color to brown.
Photo: The disease can be identified by the white coating on the leaves
As the disease progresses, the foliage begins to curl. At an advanced stage, the parasite blocks the supply of nutrients and moisture to all parts of the plant, which leads to the death of the vine. The fruits will lose their correct shape and begin to crack right on the bush.
We recommend reading: Diseases of cucumbers.
Specimens planted near the windows and doors of greenhouses are most susceptible to powdery mildew.
How to distinguish true powdery mildew from downy mildew
Powdery mildew is often confused with another fungal disease - peronosporosis (downy mildew). Both diseases are dangerous. They infect plants planted in a greenhouse. Powdery mildew also occurs in open beds, while the false variety does not affect outdoor plantings.
| Signs | Powdery mildew | Downy mildew |
| Pathogen | Oidium mushroom | Downy mildew mushroom |
| Location dispute | On the front side of the sheet plate | From the underside of the leaves |
| Symptoms | A white coating forms on the top of the leaves | A white-violet coating appears on the reverse side, yellow spots form on top |
| Changes in leaves | May curl, but rarely fall off | The leaves gradually become completely covered with spots, turn black and fall off. |
| Localization | The first symptoms appear on leaves that are located near the ground, gradually the spores move to the top of the vine | The leaves of the upper tier are affected first, the disease descends from top to bottom |
| What amazes | Most often affects greenhouse cucumbers, but sometimes appears in open beds | It progresses exclusively in greenhouse conditions; in isolated cases, symptoms appear on plants planted in open ground |
| Conditions for reproduction | Frequent temperature changes | Regular precipitation, cold summers |
| Sources of damage | Infected soil, seeds, water, plant debris | Infected seeds, water, plant debris |
| How it spreads | Spores quickly fly between cucumber vines thanks to gusts of wind | By wind, untreated tools, insects |
Photo: Externally, downy mildew differs in the color of the spots (yellow) and the location of the spores (bottom)
. Since the diseases are different from each other, the drugs that are chosen for treatment are different.
Main manifestations of fungal infections
Powdery mildew is characterized by the appearance on the outer surface of leaves and, less commonly, stems, of small white spots - these are fungal spores. Over time, their number grows, spreading throughout the plant, moving to fruits and stems. Microscopic fungi grow through the entire leaf, dry it out and contribute to its death. Visually, at this time, the tops become wavy, curl into a tube and die. When the disease is advanced, oidia spread into the soil and other crops, for example, appear in zucchini. Cucumber fruits attacked by powdery mildew become:
- sluggish;
- rare;
- with poor taste and other characteristics.
Total defeat leads to rotting.
Downy mildew in cucumbers manifests itself on the inner surface of the leaves in the form of watery gray spots with a purple or brown edging. The speed of spread is quite high - 5-7 days. In a few weeks, the entire greenhouse crop can die. Like ashtray, downy mildew can affect large plantings of cucumbers and other crops.
Obvious manifestations of both diseases are observed after prolonged rains and repeated heavy morning dew.
Disease development cycle
The development cycle of powdery mildew is the same for all types of pathogen and consists of several stages.
- Cleistothecia is the stage of overwintering on plant debris.
- Primary spring infection of plants.
- The onset of favorable conditions that promote the proliferation of the fungus by sacspores.
On a note! The incubation period of the pathogen is very short - 3-4 days. 15 generations can hatch in a season. Spores are transmitted from the greenhouse to the open beds and back.
Control measures
The most important measure to protect cucumber plantings from powdery mildew is to purchase varieties and hybrids that are resistant to this disease. If damage does occur, then all possible treatment measures can be divided into groups:
- prevention of damage;
- use of chemical and biological agents;
- use of folk recipes.
The choice of a particular method depends on the extent and extent of the lesion, as well as on the period of detection of symptoms.
If in a neighboring area the beds with cucumbers are affected by powdery mildew, then it is advisable to carry out a number of preventive measures. At the initial stage, when the symptoms have just become noticeable, it is recommended to use traditional methods of control or biological agents. In case of massive damage, plants can only be saved by spraying with solutions prepared on the basis of chemicals.
Chemicals
The use of ready-made chemicals is recommended in rare cases when there is massive damage to cucumber plantings or the disease is in the last stages of development.
Photo: Modern specialized stores offer a large selection of chemicals to combat fungal diseases
Dignity:
- performance;
- long period of action and prevention of recurrence of symptoms.
But chemicals also have many disadvantages:
- toxins are absorbed by the plant and can have a negative effect on humans;
- failure to follow the instructions is dangerous;
- parasites get used to the components of the drugs and may not respond to them in the future.
On a note! After spraying cucumber vines with solutions of chemical substances, you can eat vegetables no earlier than 20 days later.
The most effective drugs:
- Topaz. High level of danger to humans; when processing, strict adherence to instructions and safety rules is necessary. Dilute 1 ampoule (2 ml) per 10 liters of water.
- Raek. A high-quality fungicide that destroys fungus on plants in a short period of time. Efficiency does not depend on weather conditions.
- Bayleton. The drug has a broad spectrum of action, protection begins 4 hours after spraying and continues for 2-8 weeks. The duration of exposure depends on weather conditions.
- Tilt CE. It has a depressing effect on the reproduction of spores; after spraying, a protective layer is formed on the leaves, which protects the cucumbers for 2 weeks. Consumption – 40 g per 10 liters of water.
- Oksikhom. The active ingredients are copper oxychloride and oxadixyl. Requires 3 treatments per season with an interval of 10-12 days. Add 30 grams to a bucket of water. drug.
- Fundazol. A systemic drug that disrupts the proliferation of fungal spores.
- Colloidal sulfur. The drug is safe for people and animals. It is recommended to carry out processing at high temperatures: +27-32 °C. Dissolve 20-30 grams in 10 liters of water. substances.
Regular use of the same chemical preparation to combat powdery mildew causes the fungal spores to become addictive, so the treatment preparations are changed. Each season, different fungicides are used.
Biological drugs
Their main advantage over chemicals is environmental friendliness and safety for humans. It is possible to process the green mass of cucumbers even during the fruiting period. Among the effective and most popular biofungicides are:
- Alerin;
- Gamair;
- Fitosporin-M;
- Pseudobacterin-2;
- Gliding.
Treatment with such bacterial agents is effective only in the early stages of development of powdery mildew. Their peculiarity is that to obtain a positive result, numerous planting treatments are required.
Their use is more justified for the purpose of prevention or pre-treatment of greenhouse soil, since such substances not only inhibit pathogenic microorganisms, but also enrich the soil composition with beneficial bacteria, making it loose and nutritious.
Folk remedies
Preparations for combating powdery mildew based on folk recipes have long proven their effectiveness and feasibility of use.
On a note! It is worth using traditional methods if the disease is detected at the initial stage of development and several bushes are affected.
Advantages:
- environmental Safety;
- many of them can be used during the fruiting period;
- after several treatments, the symptoms of the presence of parasites disappear;
- The ingredients needed to prepare medicinal solutions are available and available at home.
As a disadvantage of such control methods, they note the low effectiveness after the first treatment, as well as the duration of preparation of solutions. Some compositions need to be infused.
Copper sulfate
A universal remedy for combating fungal infections, which has been used since ancient times. It can be used at the stage of flowering and fruit set; during the fruiting period, the drug can accumulate inside vegetables and harm human health.
Initially dissolve 100 g in 10 liters of water. crushed laundry soap. It will ensure the adhesion of the main active component to the processed vegetative mass of cucumbers.
Add 7 grams to the prepared soap solution. copper sulfate. The composition is left for 2 hours and the plantings are treated. Duration of protection is 7-12 days. It all depends on the air temperature (at 25 oC - 12 days, at 15 oC - only 7) and the presence of precipitation (rains will quickly wash away the protective layer). The treatment can be repeated every 7 days until the signs of the disease disappear.
Pharmacy drugs
Some drugs that can be purchased at a regular pharmacy are effective in the early stages of development of powdery mildew:
- aspirin (4 tablets diluted per 1 liter of water);
- brilliant green (add 1 drop for each liter);
- iodine (add 10 ml of substance to 10 liters of water);
- potassium permanganate (5 grams of the drug per 10 liters of water).
Cucumber plantings are regularly sprayed with similar solutions. It is better to do this in the evening so that the plants do not get burned from the scorching sun.
Photo: An iodine-based solution will protect plants from many problems in the early stages of damage
Wood ash
Such a solution not only protects against pathogenic organisms, but it perfectly nourishes and strengthens the plant’s immunity.
To prepare the composition, 1.5 kg of wood ash is diluted in a bucket of water and 45 grams are added. crushed laundry soap. The bushes are watered at the rate of 0.7 liters per plant.
Soda Ash
To prepare the solution you will need to mix:
- 140 l of water;
- 40 gr. crushed laundry soap;
- 60 gr. soda ash.
The resulting product is thoroughly stirred and sprayed on the cucumber plantings. Treatment is carried out no more than 3 times with an interval of 10-12 days.
On a note! You can replace soda ash with regular baking soda.
Dairy products
You can protect cucumbers from pathogenic fungi, including powdery mildew, by treating them with solutions based on fermented milk products. To do this, add 1 liter of fresh whey, kefir or milk to a bucket of water (9 liters). Plants are sprayed at intervals of 10-14 days.
To enhance the effect of the medicinal composition, you can add 10-12 drops of iodine to a bucket of water.
Mustard
You can strengthen the immunity of plants and protect against fungus with root and foliar fertilizers based on mustard.
The water is preheated to 55 °C. Then add 2 tbsp. l. powder and dissolve thoroughly.
Horsetail decoction
To prepare the medicinal composition you will need 100 grams. dry or 1 kg of fresh horsetail and 10 liters of water. First, the mixture is infused for a day, and then boiled for 2 hours over low heat.
The broth is filtered. For every 5 liters of water add 1 liter of the resulting product. Cucumber lashes are processed at intervals of 7 days.
Infusion of marigolds
If marigolds are planted on the site, they can be used to protect cucumbers from powdery mildew and other fungal diseases. You will need to collect 0.5 buckets of flowers.
The raw materials are poured with warm water and left to infuse for 2 days. The resulting mass is filtered, 50 grams are added. crushed laundry soap and spray the cucumbers at intervals of 14 days.
Photo: To process cucumber lashes, it is advisable to use marigold infusion
Marigolds planted next to cucumber beds will also protect the plants from various insects.
On a note! It is advisable to start spraying with compositions prepared according to folk recipes when the weather outside is cloudy and rainy for several days. Under such conditions, you should not wait for the first symptoms; it is better to carry out preventive treatments.
Traditional methods
The fungal disease powdery mildew can appear on cucumbers and other crops. When the first signs appear, you should quickly begin to treat the disease to prevent further spread. Folk remedies include:
- Soap and wood ash. The solution should be prepared as follows: grate household laundry, mix with ash in an amount of 200 g. Pour the mixture with heated water, stir until the soap dissolves. Process cucumbers in 3 approaches per week.
- Soda. Prepare a solution per 10 liters of liquid: soda - 100 g, vitriol - 75 g. Mix thoroughly, it is advisable to treat only the leaf mass with the solution.
- Garlic. Grind the garlic cloves with their herbs, add liquid. Infuse the product for half a day. Water the cucumber growing areas with the solution. Spray cucumbers for 14 days.
- Mullein. Dissolve in water in a ratio of 1:3. Leave the solution for 3 days. The treatment is carried out among cucumbers in ordinary beds and in greenhouses.
- Kefir. Kefir that has expired will also work. Water the leaves every 3 days.
- Potassium permanganate. Prepare a solution: 2 g of potassium permanganate per 10 liters of heated water. Spray all cucumber plantings with the product for 2 weeks or more (depending on the disappearance of signs of the disease).
It is recommended to purchase cucumber hybrids marked F1. Disease-resistant species:
- Hybrid Princess with improved taste.
- Early ripening variety Arctic, fruiting begins a month after planting.
- The hybrid Amurchonok was bred from Avangrad.
- The climbing indeterminate variety Thumbelina does not require pollination.
- Grandfather's granddaughter, the fruits of which are covered with white fluff.
- Chinese disease-resistant - has long fruits.
- The baby ripens quickly and has large fruits.
- Lenara, resistant to various weather conditions.
- Pasadena, harvests appear 1.5 months after planting the seeds.
Prevention
If you purchase varieties of cucumbers that are resistant to fungal diseases, and also carry out simple preventive measures annually, you will not have to fight the infection.
- For planting, only high-quality material is used and before sowing it must be treated with special disinfectants and growth stimulants.
- Don't plant cucumbers too early. By the time seedlings or seeds are planted, the soil should warm up to +16 °C.
- Plant the crop in properly prepared soil. It is necessary to dig up, remove all plant remains, and apply fertilizer.
- The development of powdery mildew can be triggered by an excess or lack of mineral fertilizers, so fertilizing should be balanced, timely and moderate.
- Water the cucumbers with warm, settled water.
- Follow the rules of crop rotation. The crop is not planted in the same place for two years in a row. If signs of disease are noticed on cucumbers, then the next season plants that are resistant to powdery mildew and other cucumber infections are planted in this place.
- In greenhouses, it is necessary to control the temperature and humidity of the air and ventilate it regularly.
- Before planting, it is important to disinfect the soil.
- If powdery mildew appears every year, then remove the top layer to a depth of 10 cm, and pour new soil on top.
- Plantings should not be too dense.
Photo: Watering with cold water can trigger the development of powdery mildew.
Such simple, effective measures are sometimes more effective than chemical treatments.
Greenhouse treatment after powdery mildew
After growing cucumbers in a greenhouse, it is necessary to treat the greenhouse at the end of the season, especially if there were traces of powdery mildew on the plants. There are many effective ways.
Photo: After growing cucumbers in a greenhouse, it is important to process and disinfect it
- Fumigation with a sulfur bomb. When it burns, sulfur dioxide is released into the air, which kills all viruses and bacteria. But the disadvantage of this option is that not only pathogenic microorganisms are killed, but also beneficial ones. The soil completely loses its fertility.
- Treatment with copper-containing preparations (copper sulfate, Khom, Bordeaux mixture).
- Since fungal spores will not live and develop on the walls of the greenhouse, they prefer organic matter in the soil, the structure itself can simply be washed with a weak solution of potassium permanganate. More attention is paid to soil disinfection.
- To cultivate the soil in a greenhouse, it is better to use biological preparations (Trichodermin, Sporobacterin, Fitosporin). They inhibit fungal spores and other pathogenic microorganisms, but at the same time enrich and improve the soil structure. They cannot be used together; an interval of at least a week must be maintained.
If there is mulch left in the greenhouse, it must be removed outside the shelter and burned.
How to get rid of clubroot on cabbage
Calcium nitrate is effectively used to combat clubroot in cabbage crops. When planting seedlings, add it to the hole one tablespoon at a time, then pour at least a liter of water into the hole. You will need to water cabbage or other crops at the roots two or three more times per season with a solution of calcium nitrate - 3 tablespoons per 10 liters of water.
Clubroot develops only on acidic soils; if you constantly maintain a slightly alkaline reaction of the soil, that is, deoxidize it in a timely and correct manner, you will get rid of clubroot.
Plants infected with clubroot usually droop at noon, but rise in the evening, they are retarded in growth and development, and have poor foliage with a bluish tint. Diseased plants should be dug up and burned. Under no circumstances should roots with clubroot growths or even small thickenings on the roots be placed in compost, since the spores of this fungus do not die in the compost and are then spread along with it throughout the entire area. Clubroot spores can live in the soil for 4–5 years, so you should not plant cruciferous crops for 4 years in the place where clubroot was found.
The clubroot pathogen does not like horseradish. You can plant horseradish in this place, you can simply water it with infusion of horseradish leaves (400 g of green crushed leaves per 10 liters of water, cover, leave for 4 hours, strain, squeeze and water over the soil).
As soon as you find a plant with clubroot, remove it immediately and pour the rest with milk of lime: a glass of lime per 10 liters of water. Pour a liter jar of milk under the root of each plant. Repeat after two weeks. It is useful to add vermicomposts to the holes when planting.
