White rot (sclerotinia) of cucumbers in a greenhouse: treatment, photo, fight

White rot on cucumbers is a dangerous fungal disease that can lead to significant crop loss. Especially often appears on bushes that are grown in greenhouse conditions. The main preventive measures are loose planting, compliance with watering norms and regular ventilation of the greenhouse. Treatment is carried out with drugs or folk remedies.

Causes of appearance

White rot is a dangerous disease of cucumbers and other plants. This is an infectious pathology that is spread by marsupial sclerotia fungi (Sclerotinia sclerotiorum). Therefore, it is also called sclerotinia. Since sclerotia are found almost everywhere, it is impossible to completely exclude the possibility of the onset of the disease.

There are several factors that provoke the development of white rot of cucumbers:

1. Wind – it is he who spreads spores over long distances.
2. Adding new soil – there may be spores and mycelium of white rot, as well as other fungi.
3. High humidity – this factor is especially dangerous when growing cucumbers in a greenhouse.
4. Night cold snaps, temperature changes weaken the plant and make it vulnerable to various diseases, including white rot.
5. The use of cold water, especially in hot weather – it is in such conditions that fungal spores germinate well.
6. Thickened plantings of cucumbers increase moisture. It also creates a favorable environment for white rot.
7. Sowing dill, parsley and other crops to cucumbers, which also increase planting density and, accordingly, provoke the spread of the disease.

Symptoms of the disease

White rot affects all parts of the cucumber, except for the roots. The main signs of the disease are:

1. Numerous white spots on different parts of the stem, fruits and leaves: they look like cotton wool.
2. The tissues of the plant soften and become loose.
3. Mucous growths appear, from which drops flow.
4. A white coating forms on the affected parts.
5. The tops of cucumbers die off and wither.
6. Black sclerotia are formed – fungal spores that begin to spread further with the wind.

Cucumber stem affected by white rot

As a result, the affected parts turn yellow and rot. They dry up, the fruits do not develop and die. All affected tissues begin to soften, which can lead to the death of the bush.

What is dangerous disease

The main danger of white rot is that it affects cucumbers very quickly. As soon as the spore gets on the surface of the plant, it multiplies, parasitizing on it. As a result, leaves and fruits are massively covered with white spots.

Another risk factor is the exceptional fertility of the fungus. Even one spore is enough for the pest to begin to multiply. Therefore, the probability of defeat always remains quite high.

White rot spores are able to penetrate cucumber tissues through the pistil. Even if the cucumber bush does not have mechanical damage (breaks, scratches), it still risks suffering from the disease. Since white spots cover the fruit, they quickly deteriorate. Spores spread to neighboring plants, which threatens to lose most of the crop.

How to treat and how to process white rot on cucumbers in a greenhouse

You can eliminate white rot, but you should start processing as soon as possible. The infection spreads very quickly. For treatment, chemicals, biological fungicides and folk remedies are used.

Ordan and other fungicides are used to fight the infection.

Chemical fungicides

Chemicals are highly effective, but they are often toxic to humans, animals, soil bacteria, and beneficial insects. Therefore, treatment with such drugs is carried out only in advanced cases, as well as for prevention (it is enough to spray once). The main preparations against white rot of cucumbers are:

1. “Ordan” is a low-toxic agent (hazard class 3 for humans) of universal action. Helps to cope with white rot and other fungal infections of cucumbers. From the moment of the last treatment to harvest, at least five days must pass, the maximum allowable number of sprays per season is three.
2. “Abika-Peak” – a drug against white rot, low toxicity to humans and bees (hazard class – 3). The waiting period from the last processing to harvesting cucumbers is at least 20 days. Three sprayings can also be done per season.

   

3. “Bordeaux mixture” – a universal preparation for white rot based on calcium hydroxide and copper sulfate. It is highly effective – it destroys fungal spores, including those in a dormant state. Toxic to humans (grade 2). The waiting period before harvesting cucumbers is 15 days. The number of sprayings is a maximum of three per season.

   

4. “Oxyhom” is a low-toxic fungicide against white rot of cucumbers (hazard class for humans and bees – 3). It has a short waiting time – 5 days. At the same time, the maximum number of sprayings per season is also three times.

   

Processing is carried out 2-3 times with an interval of 10 days. Spraying is best done in the late evening. If cucumbers grow outdoors, the event should be scheduled on days when the weather is dry and calm.

Biological method of treatment

During the fruiting period of cucumbers, it is better to use not chemical agents, but biological fungicides to combat white rot. They contain colonies of bacteria that effectively destroy fungi. At the same time, such preparations are safe for plants, animals, beneficial insects.

Cucumbers are best processed late in the evening.

Biofungicides include:

1. “Gamair” is a non-toxic drug against white rot (hazard class 4 for humans). Processing can be carried out up to 3 times per season, while there is no waiting period – the crop can be harvested immediately.

   

2. Alirin-B is another non-toxic drug with similar characteristics. There is no waiting period, the number of treatments is up to 3 per season.

   

3. “Planriz” is a bacterial preparation that is safe for humans, bees, and fish. There is no waiting period.

   

Treatment of white rot on cucumbers with folk remedies

Folk remedies for white rot of cucumbers show their effectiveness if the disease has not yet been started. For processing, a paste is prepared to lubricate the affected stems, or a solution that is sprayed on all bushes (including healthy ones for prevention). The recipes are:

1. Shavings of household or tar soap (3 tablespoons) are mixed with the same amount of wood ash. The result is a paste that is smeared on the affected stems. In this case, the leaves are treated with other solutions. If they are badly hurt, they just cut off.
2. Another method of treating white rot on cucumbers in a greenhouse is whey treatment. To do this, you can take both milk (1 l) and an alcohol solution of iodine (10 ml) per 10 l of water. It is also recommended to add 2-3 tbsp. l. laundry or liquid soap.
3. A solution of baking soda with potassium permanganate. Both powders are measured in 8 tbsp. l., dissolved in 1 liter of water, add 1 tbsp. l. shavings of laundry soap and begin processing.
4. Damaged cucumber stems are smeared with a mixture based on chalk, water (1: 1) and fungicide.

Agrotechnical events

Agrotechnical measures also prevent the development of white rot in cucumbers. It is recommended to choose varieties that are resistant to this disease: Sportresisting, Improved Telegraph, Connie, Zozulya, Claudia.

At the same time, individual varieties, on the contrary, are vulnerable to sclerotinia. We are talking about varieties such as Farmer, Swallowtail, Regia, Graceful, Emerald and others.

Zozulya is one of the varieties resistant to white rot.

Other agrotechnical measures include:

1. Thinning plantings – cucumbers are placed at a distance of at least 40 cm from each other. And if the growing method is horizontal (without tying a thread to the ceiling of the greenhouse and without installing supports), then the distance is taken with a margin – at least 60 cm.
2. Timely destruction of rotten parts of cucumbers, including fruits. If the cucumber bush has suffered significantly, it must be dug up, carried away and burned.
3. To prevent white rot, crop rotation should be observed – cucumbers should not be planted in beds where parsley or celery grew. These plants are vulnerable to sclerotinia.
4. Creating optimal conditions for cucumbers – normal moistening, constant ventilation of the greenhouse, mandatory preventive treatment of cucumbers with fungicides or folk remedies.

preventive measures

It is easier to prevent the development of an infection than to treat cucumbers. To do this, experienced gardeners recommend taking several measures:

1. Periodically ventilate the greenhouse, especially in hot weather when it rains (high humidity).
2. Water cucumbers only with settled water (at least 12 hours).
3. When growing cucumbers in a greenhouse, the upper part of the soil 20 cm deep should be changed periodically. Moreover, before laying the new soil, it is watered with a solution of a fungicide or potassium permanganate (concentration 1%). After a few weeks, it should be treated with “Azotobacterin” or other bacterial fertilizer to restore the natural microflora.
4. Follow the watering rate. Cucumbers require good hydration, but you should not get carried away with water either. Watering is carried out every 4-5 days. In order for the soil to retain moisture longer, plantings are mulched with hay, sawdust, peat or other material.
5. Also, to prevent white rot, seedlings of cucumbers after transplanting into the ground should be treated with fungicides. Spraying is carried out in a week, and then – as needed.

Conclusion

White rot on cucumbers spreads quickly, but it can be dealt with, especially if the spots are noticed at an early stage. If symptoms are detected, not only the affected bushes, but also neighboring plants should be treated.