What is late blight, how does it appear on tomato seedlings and how to get rid of it?

The taste and beneficial properties of tomatoes have been known for a long time. They improve your mood and even have healing properties. But what if the plant itself gets sick - its leaves begin to become covered with dark small spots, turn brown, dry out and fall off, and the stems and fruits turn black? What kind of disease is this? Let's try to understand the problem, find out methods of prevention and ways to combat the disease.

What it is?

Late blight (lat. Phytophthora) is a fungal disease of vegetables of the nightshade family (tomatoes, eggplants, potatoes and others). Science knows more than a hundred species of this fungus, which spreads by spores on the ground and through the air. Infection can be everywhere - in the soil, in plant organs, in seeds, even on gardening tools.

The fungus infects all vegetables and fruits growing in a garden or greenhouse. It penetrates everywhere, infecting household items and household utensils.

Phytophthora is a frost-resistant fungus that persists in the ground for several years, causing damage to vegetable crops and destroying them.

How does the disease manifest itself on tomatoes?

The harvest can only be saved in the early stages if signs are noticed on the stems. If leaves and fruits are affected, the plant must be eliminated. What symptoms are used to recognize the disease?

• Brownness appears on the stems;
• The leaves become covered with brown spots. Then they begin to dry out and subsequently fall off;
• The inflorescences turn yellow, then darken, dry out and fall off;
• The fruits are also covered with brownness, which spreads, causing the fruits to rot and smell unpleasantly;
• If it rains outside, the affected tomato leaves are covered with an oily film.

Photo

Next in the photo you can see what late blight looks like on tomato seedlings.

Reasons for appearance on tomatoes

The pathogenic fungus is a very viable organism and lives everywhere:

• on the ground;
• in the air;
• on the roofs, walls of greenhouses and country houses.

It appears on tomatoes for a number of reasons:

1. a sharp change in weather conditions (in summer it is hot during the day, cool at night, and dew forms in the morning);
2. poor evaporation (due to dense bushes and cramped beds);
3. proximity of tomatoes to other vegetable crops infected with fungus (potatoes, peppers, eggplants);
4. lack of air movement, poor ventilation (this applies to greenhouses and greenhouses);
5. the presence of a large amount of nitrogen fertilizers in the soil;
6. lack of useful microelements;
7. the presence of lime in the area where tomatoes ripen;
8. cloudy, rainy weather;
9. frost resistance of late blight, which retains its viability on the harvested crop until spring.

Causes and favorable factors for the development of the disease

Phytophthora spores are extremely resistant to changes in external conditions, therefore they remain viable even under extremely unfavorable factors.

Late blight is diagnosed more in young plants, due to a number of reasons:

• Phytophthora spores begin to show activity already at a temperature of +10°C;
• high humidity, characteristic of growing seedlings in greenhouses, is a favorable environment for fungus;
• a related factor is the difference in night and day temperatures, as well as short daylight hours.

Violation of the rules of agricultural technology also leads to late blight: thickening of crops and untimely picking, non-compliance with ventilation and watering regimes, insufficient lighting of seedlings, an imbalance of micro and macroelements in the soil.

Signs of illness

Late blight disease looks like rot. This is explained by the fact that the infection develops under the influence of moisture.

Tomato disease is determined by the following characteristics:

• the presence of a whitish coating;
• dark brown spots on leaves, fruits, stems;
• withering and drying of the entire vegetable crop;
• unpleasant smell of vegetables;
• unsuitable for consumption.

Read on to learn how the disease develops and spreads.

Video: effective remedies for late blight

But it is much easier to fight late blight in a greenhouse than in the open air. Because there we ourselves can create a certain microclimate, but in open ground this is impossible. In a greenhouse, for example, from the moment the fruits are filled, we can reduce watering, thereby reducing humidity and blocking the path of late blight. If the fruits are already large and they just have to ripen, you need to gradually cut off all the leaves from bottom to top, thereby improving ventilation in the greenhouse and opening the sun to the fruits.

Treatment of tomatoes against late blight should be carried out using biological means whenever possible, otherwise the fruits will be saturated with chemicals. And we can buy such fruits in the store.

How does the disease develop?

1. A light coating appears on the back of the sheet.
2. Then yellow spots with darkened areas form, increasing in size, they destroy the leaf, which turns black and falls off.
3. Next, the tomato fruits begin to turn black on the bottom - most of the moisture collects there, and then they become soft, emit an unpleasant odor, and become unsuitable for eating.
4. The same thing happens to the stem of a tomato - a coating appears, the stem turns black and withers.

The disease spreads within 7-10 days. Crops growing in the area become infected with spores of the pathogenic fungus and die. Please note that late blight disease has no cure. The best way out is to remove the diseased tomato from the garden and give healthy vegetables preventive treatment.

Methods for processing tomatoes

To combat late blight of tomatoes, various treatment methods are used. They are used at different stages of development of tomato bushes - during pre-sowing seed treatment, when transplanting grown seedlings to a permanent place, as well as when identifying the first signs.

1. Seed treatment - for pre-soaking seeds, you can use Fitosporin or other fungicidal preparations, as well as a solution of potassium permanganate or hydrogen peroxide.
2. Processing of seedlings - when planting tomato seedlings in a permanent place, they can be sprinkled with wood ash or tobacco dust. This will protect against the development of fungal microorganisms and additionally feed the seedlings.
3. Watering – Fitosporin solution can be used to treat the soil on the site. It not only effectively destroys fungal spores, but also improves the structure and composition of the soil. You can also use a hydrogen peroxide solution for this purpose.

Regardless of the method used for processing tomato beds, you need to remember that watering or spraying the plants is carried out only in dry and windless weather. Best time is early morning or late evening. The sun's rays can cause burns on wet tomato foliage and stems.

How to fight, how to treat seedlings?

To combat the disease of tomatoes - late blight, there are many folk remedies and chemicals. The adaptability of the fungus to different drugs suggests that the means to combat it need to be changed more often.

Folk remedies

Not all owners of dachas, vegetable gardens, and farms want to use chemicals. Many people prefer to get rid of pathogenic fungus using traditional methods. Such compositions for treating seedlings and treating tomato diseases are environmentally friendly and consist of natural products.

Garlic infusion

1. Garlic (leaves, arrows, roots) - grind 100 grams in a meat grinder, add water (250 grams), leave for a day.
2. Next, strain the infusion through cheesecloth, dilute it with water (10 liters), add potassium permanganate (potassium permanganate) - 1 gram.

It is necessary to treat tomatoes with garlic infusion every 10-15 days.

Milk serum

Dilute the serum with water in equal proportions. The plant can be treated with this solution once a week starting in July.

Infusion of straw or hay

1. Fill rotted hay or straw with water in the amount of 10 liters.
2. Add a little 46% nitrogen and leave for 3 to 4 days.
3. Strain the solution and spray the tomatoes after two weeks.

Milk with iodine

Dilute low-fat milk (1 liter) with 10 liters of water, add iodine (15 drops). Spray the resulting liquid over the tomatoes 2 times a month.

Salt

Add 1 glass of salt to 10 liters of water and stir. Treat with this liquid once a month.

Copper sulfate solution

Dilute 2 tablespoons of copper sulfate in 10 liters of water. Spray vegetable seedlings.

Yeast

At the first signs of late blight, treat the tomatoes with a yeast solution - dilute 100 grams of yeast in 10 liters of water.

Treatment with specialized preparations

Before sowing, seeds must be treated with special chemicals designed to combat fungal plant diseases within 7-10 days.

When planting seedlings in the ground or greenhouse, parts of plants damaged by late blight must be cut off, and in case of severe damage, it is better to throw away the entire bush if treating the plant is useless. Treat the remaining crops with chemicals.

In the store you can find several drugs to combat fungus at an early stage of plant growth. Available for sale:

• Fitosporin-m - 60 rubles per package weighing 200 grams.
• Alirin-B - 20 tablets costing 70 rubles.
• Ordan fungicide - 25 grams for 50 rubles.
• Baikal EM1 - costs 110 rubles. for 500 ml.
• Radiance Em1 - concentrate for 3,000 liters costing 450 rubles.
• Bordeaux mixture - 250 grams costing 51 rubles.
• Previkur-Energy - bottle (60 ml) for 360 rubles and others.

All drugs are used strictly following the instructions. The entire process of tomato growth and temperature conditions in the greenhouse must be controlled, because This disease manifests itself only under certain conditions and develops very quickly.

You should not forget to fertilize the soil with phosphorus and potassium, but do not overuse nitrogen.

Other methods

1. In the fight against late blight, it is proposed to use Trichopolum tablets, which are sold in every pharmacy at a price of 87 rubles. For treatment, you need to dissolve 1 tablet in a liter of water.
2. A good remedy for treating seedlings is bleach.
3. To disinfect with a sulfur bomb, it is necessary to caulk all the cracks so that when fumigating the room, smoke does not escape from the greenhouse. The number of tablets used depends on the volume of the building. The saber burns for several hours, but this drug lasts for three days.
4. Another way to protect a plant from fungus is to sprinkle the seedlings, after planting in the ground, with ash between the rows before watering. This treatment is repeated when the inflorescences form fruits.
5. Copper wire with a diameter of 1 mm helps in the fight against fungal infection - it must be cut into strips up to 2 cm long, then inserted into the stem of the plant.

Means to combat late blight

The fight against late blight on tomatoes includes disease prevention and direct treatment. Prevention of late blight on tomatoes includes firstly , the correct planned placement of crops in the garden, that is, the proximity of nightshade crops, namely potatoes and tomatoes, is not recommended. Secondly , timely destruction of plant debris affected by late blight. Thirdly, correct agricultural technology for growing tomatoes, since its violation also increases the risk of late blight - namely, the impact of dense plantings, mutual shading of plants and insufficient pruning of leaves.

It is best if onions, garlic, basil or savory grow along with the tomatoes. And in the neighboring beds there will be beans, cabbage, lettuce or radish.

Tomatoes are more prone to infection if the soil is oversaturated with nitrogen fertilizers, and, conversely, the plant’s immunity is higher if there is a sufficient amount of potassium and phosphorus in the soil.

Protection against late blight also includes seed treatment, since very often the disease enters the beds precisely from seeds obtained from a diseased fruit.

Treatment of late blight includes a set of measures to restore the plant when it is already infected. Next, we will consider specific effective measures to combat late blight in tomatoes.

Prevention measures

Prevention of tomato diseases from late blight must begin in advance - in the fall of the previous year.

1. At the end of the harvest, remove all remaining plants to prevent fungus.
2. Thoroughly disinfect all garden equipment.
3. On a cleared area of ​​land, plow through and place nettles in the depressions in a layer of 5-10 cm.
4. Plant plants to improve the soil structure and prevent the growth of weeds (mustard, peas).
5. At the seedling stage, begin to strengthen the immunity of the vegetable crop.
6. Rotate locations for different vegetables every year.
7. It is necessary to water the tomatoes with a small amount of water in the morning so that moisture does not collect on the ground and tomatoes.
8. Avoid drafts and air stagnation.
9. Plant the plants further apart from each other, without creating crowding and without causing stagnation of moisture.
10. Feed tomatoes with essential microelements to strengthen the plant’s immunity. For example: zircon, humate and others.

Preventive measures

Prevention of late blight on tomato bushes involves eliminating unfavorable conditions for the development of the fungus. For this:

• Choose sunny places for planting tomatoes;
• Do not thicken the beds: air should circulate well between the bushes;
• Water only at the roots (water should not get on the leaves and stems);
• Avoid excessive application of nitrogen fertilizers.

ATTENTION! In a greenhouse, late blight rarely affects tomatoes, because it is warm inside and there are no sudden temperature changes. But sometimes tomato bushes become infected. Therefore, we must not forget about ventilating the greenhouse to combat excess air humidity - tomatoes do not like it.

Selection of resistant varieties

In order not to think about how to get rid of late blight on tomatoes, it is better to plant varieties that are recognized as the most resistant to the fungus:

1. Pickling miracle (mid-season). The bushes bear fruit abundantly with good feeding. Tomatoes weighing 100 g are ideal when salted;
2. The Little Prince (early). Tomatoes weighing up to 45 g are good in salads and canned food;
3. Lights of Moscow (early). The bushes do not require pinching. The fruits, weighing no more than 200 g, are dense, lightweight, and transportable. They have good taste;
4. Academician Sakharov (mid-season). Tall bushes produce tasty tomatoes up to 300 g, which are good for salads;
5. Orange giant (mid-season). Tomatoes contain a lot of carotene and weigh at least 350 g, and individual specimens reach 700 g. Good in salad;
6. Heart of America (mid-season). Another giant that can produce kilogram fruits in the shape of a red heart.

ATTENTION! The resistance of a tomato variety to late blight does not mean that the attack will not affect you 100%. This statement from the breeder only gives you a good chance of avoiding a fungal infection on your tomatoes. To increase them, we suggest you pay attention to other preventive measures.

Tillage

One of the preventive measures for late blight on tomatoes is soil preparation, which helps kill dormant spores of the fungus. To do this, in the fall, the remaining leaves and stems are removed from the garden. Since they can be infectious, it is better to burn them. But do not throw the tops into the compost heap - otherwise, with future fertilizing, you will spread the infection throughout the entire area.

Phytophthora spores reach tomatoes either from the air, by transfer from a potato field, or from contaminated soil. The pathogen lives at a depth of no more than 10 cm. Therefore, deep digging in the spring can destroy them. Treatment with Fitosporin will also help prevent the onset of the disease. It can be replaced with Bordeaux mixture.

Tomato seed treatment

Since tomato fruits infected with late blight without obvious signs of disease are sometimes left for seed collection, it would be dangerous to leave them untreated. To destroy fungal spores, you need:

1. Pour water at a temperature of 60 degrees into a container;
2. Place the seeds in it for 2 hours;
3. Add water during this time so that the temperature does not drop below 50 degrees;
4. Remove the seed material and dry it.

ATTENTION! It is very important to observe the temperature regime. For this you need a special thermometer: you cannot measure it accurately with your hand. If the temperature is below 50 degrees, late blight will remain on the tomato seeds. If it is more than 60 degrees, the embryos will die, and you will no longer get seedlings from such material.

Processing of seedlings

Although treating tomato seedlings against late blight will not provide a 100% guarantee of healthy tomatoes, it is necessary because:

• Increases immunity to fungal diseases;
• Strengthens the bushes, which will subsequently produce more fruit.

Fertilizing with mineral fertilizers containing phosphorus and potassium helps prevent late blight on tomato seedlings. Excess nitrogen is unacceptable - otherwise the fungus will have a good environment for development. Before planting in a permanent place, it is recommended to treat the seedlings with Bordeaux mixture (1% solution).

Compliance with crop rotation

Crop rotation is an annual change of places for cultivating vegetable crops to prevent late blight and other infectious diseases. Important for tomatoes:

• So that the bushes return to the place where the tomatoes grew no earlier than after 4 years;
• So that a lot of organic matter is introduced under the predecessors (to avoid applying nitrogen fertilizers and to prevent its excess).

Since spores of the fungal disease late blight can spread to tomatoes from neighboring nightshade crops, they need to be planted as far apart as possible. Potatoes are especially dangerous. But you shouldn’t sow peppers, eggplants or physalis next to each other. They themselves suffer from brown rot less often, but they transfer the infection to other plants very well.

Are there varieties resistant to this disease?

Tomatoes that are resistant to this infection will help you avoid late blight. These tomatoes include:

• “Lark F1”.
• “La-la-fa F1.”
• “Soyuz 8 F1”.
• "Tatiana".
• "Black".
• “Blagovest”.
• “Budenovka”.
• "Tsar Peter"
• "Dwarf".
• “Blizzard.”

But even when using tomato varieties with increased resistance to late blight, preventive measures and agricultural practices should not be neglected.

So, to prevent tomatoes from getting late blight, it is necessary to regularly take preventive measures to improve the health of the area in which they grow. For prevention and treatment, use chemicals and folk remedies. When growing tomatoes resistant to late blight, do not neglect the measures taken to prevent and spread fungal infection.

Under what conditions does fungal disease develop?

Phytophthora fungus can spread through water, air, and even through gardening tools. But the main factor contributing to its appearance is high humidity, so if the summer turns out to be damp and rainy, late blight begins to spread rapidly.

High humidity is not the only reason for the spread of fungus. You should not plant tomatoes next to potatoes: this crop is one of the first to become infected with late blight.

Heavy dew in the morning, dense plantings, cold summers, strong differences between day and night temperatures, excessive watering, as well as an excess of nitrogen or a lack of potassium, iodine, copper or manganese - all this can also be attributed to the causes of fungal disease in tomatoes.