Late blight or late blight, as this scourge is popularly called, is a very dangerous disease that, without exaggeration, in a few days can nullify all the efforts spent on growing a crop.
Late blight is the worst enemy of nightshades, especially tomatoes and potatoes. And if, when potatoes are damaged, the yield is simply significantly reduced, then tomatoes can die completely literally overnight. But this does not mean that the disease came so quickly.
Late blight fungus spores previously accumulated in plant debris and soil, awaiting their finest hour. To prevent the disease from spreading, special attention should be paid to soil treatment after harvesting plants damaged by late blight.
What it is?
Late blight is a fungal disease that affects plants . The causative agent is the fungus “phytophthora”, which in Latin means infectious plant eater. The genus Phytophthora is a mycelial parasitic organism that often leads a saprotrophic lifestyle. To date, more than 70 species of this fungus have been described, but, according to experts, another 500 varieties have not yet been fully studied.
Reference! Late blight infection occurs when the pathogen enters the plant, through damage to the leaf blade or the most unprotected place - the stomata. This is a place on the surface of the leaf that is involved in the process of gas exchange and evaporation of liquid.
But for the fungus to get inside without hindrance, water is required ; when combined in it, the spore enters the body. And how unfortunate it is, but after this the plant will die.
Take measures against late blight
The problem with late blight does not go away on its own. Without our intervention, an epidemic begins. Fungal spores are tenacious, do not die in the cold and will last for 7 years. With the onset of spring, they begin to develop and lead to repeated destruction of the crop.
The earth is infected with late blight, what should I do? You can defeat the disease in your area by creating unbearable conditions for the development of the disease. The main steps are to disinfect the ground. You can cure the infected area in different ways:
- plant green manure;
- fumigate greenhouses with sulfur bombs;
- spill the soil with bactericidal solutions.
Inaction is unacceptable. Particular attention should be paid to infected tops and tubers, as this is a source of infection. They must be taken away from the territory, or doused with kerosene and burned.
Rotten tubers and collected tops must be immediately removed from the site or burned, otherwise the pathogen will develop further when it gets warmer
Do not bury diseased stems - this is a breeding ground for pathogenic organisms. Once opened, the infection will spread through the air and the problem will remain.
Photo
Check out the photos of late blight below:
Soil disinfection
In the first year, I shed the soil twice: in the fall, after cleaning the greenhouse (with copper sulfate, out of fear) and in the spring, 2-3 weeks before planting the seedlings. Then only in the spring. For disinfection I now use only peracetic acid. I make it myself, it’s very simple - to 1 liter of 9% table vinegar I add 200 ml of 3% hydrogen peroxide, and put the mixture in a warm, dark place for 7-10 days. I use it in the proportion of 1 glass per bucket of water. Six liters of acid is enough for me to spill 6 beds in two greenhouses. In monetary terms, the product costs approximately 200-250 rubles (5 liters of vinegar + 1 liter of hydrogen peroxide).
Why did I choose this particular method of soil disinfection? Peracetic acid is an organic acid that does not accumulate in the soil and, under the influence of the environment, decomposes into acetic acid, water and oxygen within two weeks. I use it in a fairly weak concentration, so the product does not acidify the soil. However, despite all this, peracetic acid is a very powerful disinfectant; it is effective against a huge number of microorganisms. At the same time, it acts much softer than copper sulfate. It can be used in the range from 0 to 40°C. For me, this is the most optimal means for shedding soil.
Related article: Bicol for potatoes against Colorado potato beetles: instructions
After disinfection, I cover the beds with a transparent film, as a result of which a greenhouse effect is created, since the sun's rays hit the ground without obstacles, while the moisture does not evaporate and the ground warms up much faster
A week after disinfection, I repopulate the soil with Trichoderma. By the way, I do this throughout the season approximately once every 3-4 weeks.
Regarding Trichoderma. I grow it myself, so I am confident in the quality and know that it really works. Today there are many drugs on the market based on this fungus, but, as it turned out in practice, not all of them are of high quality (for example, I could not grow the fungus from the drug Glyokladin brand “Oktyabrina Aprelevna”).
Where and when is it formed?
Pathogenic microelements are stored in affected tubers of vegetables left in the ground after harvesting, in compost heaps along with the tops of diseased plants, in the soil, on the walls and roof of the greenhouse, in seeds, and on gardening tools. The main task of the gardener is to prevent the spread of harmful microflora. Late blight prefers:
- soils with a lot of lime;
- dense plantings, this happens in greenhouses where there is no access to air for ventilation, high humidity and temperature are maintained;
- sudden temperature changes, which result in the formation of dew - an additional source of moisture;
- plants with weakened immune systems;
- excess nitrogen fertilizers in the soil.
Attention! With the arrival of spring, harmful organisms begin to actively develop.
The trigger is suitable conditions: ambient temperature above +10°C; humidity 75%, which last for several days. Together with raindrops, spores fall into the ground or infect the vegetative areas of young plants through wounds, leaves, tubers, and stems.
Actions in case of infection in a greenhouse
Late blight is a disease that cannot be completely cured. Agricultural crops can be protected from it by suppressing the activity of harmful microflora. The means for treating plants planted in a greenhouse and in an open area are the same. In any case, there should be several sessions, otherwise the beneficial effects of chemical compounds and folk methods are unlikely to manifest themselves.
It should be noted that when destroying late blight in a greenhouse, the risk of poisoning is much higher than when carrying out treatment in the fresh air. To avoid this, the gardener must take all precautions.
Why is it dangerous?
The harmfulness of this disease lies in the fact that, despite the long period of ripening of the pathogen, it is able to infect the entire crop, for example tomatoes, in a matter of days. Gray spots appear on vegetables, around which there is a white coating .
Hence the second name of the disease – “gray rot”. The plants rot, and the fruits, accordingly, lose their marketable appearance and deteriorate during transportation or storage.
The fungal pathogen is resilient and does not die even from winter cold. Phytophthora also causes loss of crop quality, infects seed materials, and affects plant resistance to other diseases.
Green manure against late blight
Proponents of organic farming, who use green manure to improve soil health and increase its fertility, recommend using their special properties. Disinfectant plants that help cope with fungal spores in the soil include oilseed radish, white mustard, calendula and phacelia. Oil radish is sown in autumn, the rest - in spring.
The sowing time is determined by counting: 30 days for seed germination and growth of root and green mass, 10-15 days for rotting of cut greens and roots. When a warm spring is imminent, the formation of green manure buds often begins earlier than expected; this is closely monitored. At the budding stage, the disinfectant properties of herbs are reduced, so the grass is cut off earlier.
Calendula is a well-known medicinal plant. To use it for medicinal purposes, including for soil, hybrid varieties are not used, since they are of little use.
The fight against late blight should not stop for a minute. From the first warm days of spring until harvest, summer residents need to vigilantly monitor the planting of nightshades and strawberries. It is not enough to cultivate the soil in the spring, because no means have yet been invented that can kill oomycetes once and for all. Whatever drugs are used, they can only reduce the number of pathogens. Therefore, it is necessary to protect the garden from the disease in a comprehensive manner, using all available means and possibilities - from preventive tillage in the spring to pre-winter harvesting of plant residues and their disposal - as well as strictly observing the rules of crop rotation and agrotechnical subtleties of growing crops.
What crops does it affect?
First of all, the disease late blight affects the nightshade family , which causes significant harm to gardeners. As already mentioned, this disease is extremely terrible:
- for nightshades, affects peppers, tomatoes, eggplants, potatoes;
- cucumbers, zucchini, squash;
- citrus fruits;
- strawberries, strawberries;
- grapes, currants;
- buckwheat;
- castor bean and other plants.
How to “drive away” late blight from a site forever – the successful experience of our reader
Adding an article to a new collection
At the mention of late blight, many gardeners and gardeners look sadly towards their plantings, followed by a heavy sigh. Do not despair! Let's give a worthy rebuff to the insidious disease that is already “taking an eye” on your potatoes and tomatoes.
Our reader from Nizhny Novgorod shared her personal experience of successfully combating late blight.
A little background. In the first year of gardening in a new place, I simply did not know about the high background of soil contamination with late blight. Therefore, of course, I was not ready and used only Fitosporin, which was familiar to me at that time. The result, naturally, was deplorable - my tomato bushes “burned out” already at the end of July. As it turned out, this picture was common in our village. After crying over my tomatoes, I decided not to put up with it, like my neighbors did.
The winter was fruitful - tons of sources were studied. By spring, a prevention and control plan was ready. I met the second season fully prepared, and it was quite successful. My tomatoes still got sick, of course, but I was able to “stretch” them in the greenhouse until October and they looked pretty decent. The harvest was also pleasing, and not a single tomato went to the landfill. Over the next couple of years, my plan underwent a slight correction, and now I am no longer afraid that one day, when I come to the greenhouse, I will see black tomato bushes.
I want to share my plan to combat late blight, I think it can be useful to many of us. The article is devoted to methods of processing soil and greenhouses, as well as methods and frequency of processing tomatoes.
How to detect?
The first signs appear a week after infection.
Main symptoms: brown or brown spots surrounded by a white border are noticeable on the lower leaves, which spread quickly. These spots are foci of the disease, which in later stages can cover the entire plant. Late blight causes severe damage specifically to tomatoes and potatoes .
On tomatoes
When late blight appears on tomatoes, dark, moist, round areas appear on the stems. After rain, a white coating can be seen on the underside of the leaf blade. Brown spots also appear on tomato fruits, which quickly increase in size and can spread to healthy vegetables.
Therefore, it is important to immediately throw away damaged tomatoes and not leave them on the bush. But it happens that the signs of the disease change, becoming in the form of circles with yellow and brown stripes, dark rings with a yellow border, or like oily, depressed inclusions.
On potatoes
The appearance of this disease is noted on tubers, trunks, and leaves. The development of potato late blight begins during the flowering period. You can see brown leaves at the bottom of the bush, then the spores spread and damage the upper parts of the young shoots. The foliage turns black, withers and dries out.
Important! If the disease is not stopped, the plant will subsequently die completely.
What does it come from?
Damage to plants during late blight is caused by oomycetes, which until recently were classified as fungi, but are now classified as a separate group of special mycelial organisms. Phytophthora specializes in nightshade representatives, so potatoes, eggplants, tomatoes, peppers and physalis become their victims in garden beds.
Oomycetes spend most of their life cycle in the spore phase, located in the soil and the remains of diseased plants. Only with the onset of favorable conditions do they begin active life activities, the purpose of which is to leave offspring. When the air is heated to a temperature of +25 - +30 ° C, spores in dew drops can germinate and infect the plant within an hour.
Late blight is especially active during sudden changes in daily temperature, when the heat of the day gives way to rather cool nights, which contributes to frequent fogs and heavy dew. Frequent rains in late July and early August also contribute to its spread. But dry weather, as well as heat above +30 °C or cold weather down to +10 °C and below, lead to an almost complete freeze of the pest’s vital processes.
Late blight affects almost all parts of plants: gray-brown spots appear on leaves, fruits or stems. At the same time, in rainy weather, diseased plants rot, and in dry weather, they dry out and break. Spores from them are washed into the ground, and are also actively spread around by drops of water and gusts of wind.
Penetrating quite deeply into the soil, late blight spores successfully survive winter frosts and again begin to attack nightshade crops in the summer. They can also overwinter quite safely in the remains of infected plants abandoned in the garden.
How to get rid of late blight?
Unfortunately, a universal way of fighting has not been found. To eliminate it, you should resort to agrotechnical measures and treatment with chemicals.
How to treat the soil?
Many gardeners and vegetable gardeners are wondering: how to treat the soil against late blight in the spring? To destroy late blight spores in the ground, it is necessary to use fungicides , as well as microbiological substances. In the spring, a month before planting seedlings or other seeds, fungicides are applied to the soil. For these purposes the following is used:
Fitosporin-M;- copper sulfate;
- burgundy mixture;
- Ordan.
Soil disinfection works like this::
- Dilute a 2-3% solution of copper sulfate.
- We cultivate the ground with the resulting mixture.
- Then we dig up the area.
- We water the soil with a solution of Fitosporin, which is pre-prepared as follows: 1 tablespoon is diluted in 10 liters of water. This mixture is enough to water 10 m2 of area.
- Flower beds are treated with Ordan solution.
Microbiological agents can be used not only in spring , but throughout the year. Just exclude the period of flowering of crops, because treatment at this time can provoke the death of bees.
Disinfection of a greenhouse in spring
In order to prevent and prevent further infection by fungal infections, greenhouses need to be disinfected. If it is not removable, then all the walls inside must be washed with a soda solution (200 g of soda is needed for 10 liters of water). Afterwards, rinse everything with water under pressure, preferably from a hose.
Also, in early spring or late autumn, you should set fire to sulfur bombs in the greenhouse or light a piece of woolen fabric. In this case, the doors must be tightly closed for 24 hours to prevent air from entering. There is another method - dusting the greenhouse , mix wood ash with tobacco dust in a ratio of 1:2, respectively. Rub the surface of the greenhouse with this mixture and sprinkle the soil.
Reference! You can treat the entire greenhouse from the inside with a solution of Fitosporin or Baikal EM. In winter, it is advisable to remove the doors to kill the infection with frost.
Folk remedies
Many gardeners do not want to use chemicals to treat vegetable and fruit crops. Therefore, they use their own prepared preparations.
- Stir 1.5 cups of chopped garlic cloves in 10 liters of water and leave for 2-3 days. Then strain and add 2g of potassium permanganate. Spray the fruit ovaries with this infusion and repeat the procedure after 10 days. Thus, plants should be treated every 2 weeks for a positive result.
- All row spacing is powdered with wood ash before watering. The first procedure is carried out when the seedlings are planted, and the second procedure is carried out during the process of plant formation.
- Take 0.5 liters of skim milk and add 7-8 drops of iodine. And they also spray the crops every 2 weeks.
- 1 liter of fermented kefir is diluted in 10 liters of water and the plant is treated.
Preventive measures in the greenhouse
To ensure that the plants in the shelter do not suffer from this disease, the gardener must monitor the temperature and humidity of the air.
The list of recommended measures also includes:
- Disinfection of equipment and premises before planting. At this stage, you can use sulfur bombs. Processing must be carried out in full compliance with safety regulations.
- Compliance with agrotechnical requirements. Watering should be rare, but plentiful.
Neglecting them can lead to the death of the entire crop. Regular preventative treatment minimizes the risk of late blight infection.
Protection
To protect the crop from negative parasitic microorganisms in the garden or garden, plants should be treated with chemicals.
In fact, there are a huge number of similar substances, but the infection easily adapts to them, so it is recommended to alternate fungicides.
During the growing season, it is better to use: 1% Bordeaux mixture, copper oxychloride suspension (2g per 5 liters of water), Ditan (1g per 5 liters). These drugs have a more gentle effect . However, systemic fungicides are more suitable for treatment, which, penetrating the plant, kill the infection from the inside, thereby completely blocking its spread throughout the plant.
How to cultivate the land without using drugs
If there is no desire or opportunity to use ready-made products, gardeners advise hot tillage. There are two ways:
- Pour boiling water over the soil to a depth of at least 15 cm. The chances of getting rid of late blight will increase if you add a weak solution of potassium permanganate or copper sulfate (2 g per 1 liter) to the watering can.
- Burn the ground, observing safety precautions. The branches are laid out on the required area, watered with oil (can be waste machine oil or vegetable oil) and set on fire. If the soil is alkaline, the ashes should be removed from the garden bed; if the soil is acidic, the soil should be dug up with it.
The second method is not used in greenhouses.
Planting green manure
As long as the infection eats growing plants, green manure will not help you. Their sowing for the prevention and improvement of soil from late blight is effective in the fall. The most effective plant in this case will be mustard - white or yellow. And gardeners even call its combination with radish and rapeseed heavy artillery against late blight. The method of combating pathogenic microflora using green manure is called biofumigation.
For better biofumigation, mustard plants should be cut as finely as possible with a trimmer, and then immediately embedded in the soil.
It is based on the fact that when the plant is damaged (when the grown mustard is cut, crushed and embedded in the soil) it releases glucosinolate substances that come into contact with enzymes in moist soil. As a result, a gas is released that kills pathogenic microorganisms. Sowing is done twice. The first is at the end of summer or at the very beginning of autumn, when the harvest has already been harvested. When the grass grows, it must be mowed and buried in the ground. The second sowing is done before winter so that spring seedlings destroy the remains of harmful spores in the soil. However, not all experts agree with this method. It is considered effective for minor infestations or as a preventive measure.
Biofumigation is now a fashionable word among progressive summer residents who are keen on organic farming. I heard stories from them about the miracle of biofumigation specifically against late blight. But late blight doesn’t happen every year, because it doesn’t exist in hot and dry summers. But against the backdrop of a steady cooling and rains, I personally would not rely only on biofumigation, but would also keep synthetic medicines in reserve.
Andrey Chuikov, tomato grower
https://www.agroxxi.ru/zhurnal-agromir-xxi/stati-rastenievodstvo/sideraty-dlja-tomatov-kak-na-samom-dele-ozdorovit-pochvu-i-povysit-urozhainost.html
Prevention
- Seeds that are resistant to late blight should be planted.
- It is important to space nightshade beds away from each other.
- Remove fruits and plants affected by the disease from the site and burn them.
- Avoid overgrowing the beds, thin out the plantings and eliminate weeds.
- Protect seedlings from sudden temperature changes. It is better to plant plants after the end of night frosts or cover them with agrofibre.
- The soil should be fertilized moderately, especially with nitrogen fertilizers.
- If possible, use traditional methods of treatment as much as possible; they are more environmentally friendly and will definitely not harm human health.
- Ventilate greenhouses regularly.
The fight and treatment of the dangerous disease late blight often involves the use of toxic chemicals. Therefore, for safety reasons, use personal protective equipment. But it is better to use potent substances only when absolutely necessary.
Tilling the soil against late blight: effective means for the prevention and destruction of fungus
Late blight is one of the most dangerous diseases, which is very difficult to cure if it has already appeared on plants. Treating the soil against late blight is a mandatory measure, whether it is open ground or a greenhouse. The fungus overwinters well in the soil, as well as in plant debris. A rainy spring only contributes to its rapid spread. At a temperature of just a couple of degrees Celsius, the pathogen begins to actively develop. Late blight can completely deprive you of your harvest, so it is better to carry out prevention. It can be done using folk remedies or special preparations.
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After harvesting, it is imperative to remove and burn the tops, which can serve as a source of infection. In regions with cold winters, where the layer of soil in which crops grow freezes, the spores most often die. But if the winter is warm, the fungus overwinters well and survives. In any case, it is better to carry out preventive soil treatment than to then unsuccessfully fight the disease on the plants.
Late blight on different crops
We told you about how late blight behaves on tomatoes and potatoes, but the fungus affects not only these crops. Late blight of plants of the Solanaceae family also affects eggplants and peppers. We have described the signs of the disease, and they are not much different in other species of the family, and the methods for preventing and treating late blight are the same as for tomatoes.
However, to combat late blight on eggplants, it is better to use the preparations Consento, Antrakol and Quadris. The first treatment is carried out with Antrakol or Quadris 8-10 days after planting the seedlings in the ground, and subsequently the sessions are repeated after 12-14 days, alternating fungicides so that the fungus does not get used to the drugs.
To combat late blight on peppers, the preparations Oxychom and Barrier are used, although other fungicides can also be used. The main thing is that you do not treat plants two or three times with the same preparation.
Sometimes, in greenhouse conditions, cucumbers can also get late blight, but they can only be treated with folk remedies, which we will talk about a little later.
Fungicide help
A similar no less effective method is perfect for treating a polycarbonate greenhouse against late blight, but you need to choose a chemical product, then this liquid will also saturate the substrate.
The presence of dangerous components in the composition requires compliance with safety rules, which can be found by carefully reading the instructions for use. It is worth highlighting several of the most common names of fungicides:
- Virocide.
- Oksikhom.
- Abiga-pik.
Spraying is carried out in the morning or evening, but you need to create a suitable temperature in the room; experts believe that the optimal indicators will be 10-25 degrees.
