Phytosporosis is one of the most common fungal diseases of nightshade crops. It is impossible to completely get rid of late blight on tomatoes; the spores are always present in the soil, on tools, covering material, the surface of the greenhouse, trellises and garter ropes.
In rainy weather and sudden temperature changes, late blight affects plants: the leaves turn black and curl, and the disease begins to actively spread through the air. In two to three days, the fungus can destroy the entire crop.
Even when collecting green fruits, it cannot be preserved. Only a small part of the tomatoes reaches the required ripeness; the rest have to be thrown away.
How to recognize late blight
A characteristic manifestation of the fungus is darkening of the tops. It is affected much earlier than the fruits. Main signs of the disease:
- Individual dark brown uneven spots appear on the foliage;
- the affected greenery dries out, the edges curl;
- waxy ripe fruits become covered with brown spots;
- filamentous white mold appears on plants in affected areas;
- when cutting a tomato, a rotten core is revealed;
- the trunks become covered with black spots, begin to rot, and the bush dies.
How does tomato disease begin?
The onset of the disease due to uneven spore damage may not be noticeable. At the early stage of infection, the lower part of the leaves becomes covered with a white coating that is difficult to detect, so the onset of the epidemic is very easy to miss. Gradually, the plaque spreads to the upper part of the leaves in the form of brown spots. Following the leaves, the inflorescences are affected, and then the fruits.
Late blight quickly spreads throughout the plantation, infecting not only tomato bushes, but also other vegetables. Within three days, the leaves will be covered with black spots, and the harvest will be lost.
Prevention measures
The source of infection can be affected potatoes and eggplants. These crops should not be adjacent to tomatoes. To disinfect the soil after harvesting tomatoes, rye is sown. In spring, sprouts of winter cereals are embedded in the soil.
When night temperatures drop to +10°C, preventive treatment of tomatoes against late blight with biological preparations and folk remedies is carried out. It is recommended to treat only affected tomatoes with chemicals and antifungal solutions.
Mass pruning of leaves and shoots is carried out. Plantings are thinned out as much as possible to provide the plants with the necessary ventilation. The soil is cleared of weeds, mulched with dry peat or covered with straw. When morning dew appears, reduce watering.
In open ground, the soil near the trunks is covered with old newspapers to absorb excess moisture. Stop organic and mineral fertilizing.
Methods for treating tomatoes from late blight
There are two types of treatment for late blight: chemical and folk.
Chemicals used to treat fungus include:
- home;
- furatsilin;
- phytosporin;
- trichopolum;
- Metronidazole.
How to treat:
- Khom is a contact fungicide containing copper oxychloride. Hom can be treated 3-5 times a season in the morning or evening, but no later than twenty days before harvest. It lasts for about two weeks and is easily washed off with water or rain. The solution is prepared from 40 grams of reagent per 10 liters of water; it is not suitable for storage. When preparing the solution, you must wear protective clothing.
- Copper oxychloride acts on the surface of the fruit and foliage without penetrating inside. But it is more suitable for preventive actions. It does not have a cumulative effect, so it is not addictive to fungi.
- Furacilin is an antibacterial drug, so its solution can be stored throughout the season. To prepare, you need to crush and dissolve 10 tablets in 10 liters of water. Spraying with furatsilin is carried out 3 times: before flowering, when the ovary appears and when the fruits ripen.
- Fitosporin is a pesticide containing bacteria and is biologically safe. This drug is able to penetrate inside the plant, thereby killing all harmful bacteria. For the solution, you need to mix 2 teaspoons in 10 liters of warm (no more than 35 degrees) water in a plastic bucket, metal is not suitable, and let it sit in the sun to activate the bacteria. Treat with phytospirin every 10 days or after rain.
- Trichopolum and metronidazole are antimicrobial and antifungal drugs. The solution requires 2 tablets. Apply once every ten days and after rain.
Folk remedies include whey, kefir, vinegar, salt, soda, garlic or toothpaste.
Fighting the disease
When the spread of fungal spores could not be avoided, the question arises: how to spray tomatoes against late blight. Drugs are divided into three groups:
- biological – harmless to insects and humans;
- chemical – artificially created fungicides; infusions of plants containing poisons (celandine, cherry and others);
- non-traditional - the use of medications that have an aseptic effect as a protective measure; medicinal antifungal tablets.
Reasons for the development of late blight
Even if late blight treatment was carried out successfully, it will arise again next year if the reasons why its active spread begins are not eliminated. The main reasons are:
- Close proximity of bushes and, as a result, disruption of free air flow;
- Neighborhood with potatoes;
- Lack of heat and differences in night and day temperatures;
- Increased precipitation;
- Excessive fertilization with nitrogen substances;
- Excess lime in the soil;
- Watering is carried out not under the bush, but on the leaves;
- Lack of beneficial microelements, resulting in weak immunity in plants.
How to properly process
After treatment, the fruits will remain toxic for 5 to 12 days, so all ripe and partially unripe tomatoes are collected before spraying.
Basic rules for spraying plants:
- glassware is used to prepare solutions;
- treatment of plants is carried out in dry, windless weather, in the evening, to avoid burns;
- personal protective equipment must be used: gloves, masks, goggles; contact of chemicals with mucous membranes is especially dangerous: eyes, nose, upper respiratory tract
- treatment of tomatoes against late blight in open ground is carried out in a targeted manner to avoid contact of solutions with neighboring crops;
- in greenhouse conditions, in addition to plants, all surfaces are treated: glass, doors, visible foundation frame, trellises, soil;
- frequency of treatment is no more than once a week.
Late blight resistant varieties
There are tomato varieties that are naturally resistant to phytosporosis. It’s easy to choose the option that is most suitable for the greenhouse or beds. Among them there are giant varieties, with massive branches, and miniature, compact ones. The shape of the fruit can be fantastically beautiful or very practical. They will add confusion if you already have a favorite variety. They will become the wind of change. They will allow you to take a break from stereotypes. These include:
- Tomato Top Ten. A low-growing hybrid with exotic yellow fruits, early ripening. Used for preparing salads and canning, it has an excellent taste.
- Grape. Mid-season variety with small red tomatoes, bush height up to 2 m. The clusters are spectacular, reminiscent of an ear.
- Lady fingers. A very popular option. Tomatoes are similar to berries. The bush is undersized. Refers to unpretentious varieties.
- Dietary big man. An original variety with large orange fruits, branches up to 1.5 m in height. High-yielding, early ripening.
- Zhigalo. The height of the bush is up to 0.5 m. The color of the fruit is red.
- Asvon. The bush is miniature. Doesn't need tying. It grows no more than 45 cm in height. The fruits are small, red in color, and ripen 95-100 days after planting.
- Compact Kakadu variety with large red fruits and early harvest.
- Leningradsky early ripening. It bears fruit 85-100 days after completion of planting. The tomatoes are small, red, juicy.
Many other varieties have high levels of late blight resistance. By choosing one of them, you can forget about this trouble. However, if potatoes or another crop that is attractive to a harmful microorganism grows nearby, problems still cannot be avoided. The tomato plantation will survive, but the potato plantation will not.
It is important to carry out preventive spraying in a timely manner. Cut infected leaves, tubers, and rhizomes must be burned and the compost treated with copper sulfate or similar preparations. It is advisable to grow companion plants nearby, green manure. The country and every family needs food supplies. Tomatoes are one of the main products in the human diet. These measures will save you from losses and unnecessary expenses.
Biological drugs
Fitosporin has a broad spectrum of action, contains bacteria that reproduce on phytosporosis spores.
Baktofit is a less effective fungicide (65-70%), used for preventive treatment.
Baikal-Em increases resistance to phytosporosis and has a beneficial effect on beneficial microorganisms.
Planriz or rhizoplan is effective against all types of rot.
Alirin-B is a tablet analogue of phytosporin. Contains strains of active bacteria.
Where does late blight come from: causes of the disease
Late blight of tomatoes occurs when the plant is infected with the oomycete (fungus-like organism) Phytophthora infestans. Infection occurs through spores that are dispersed by the wind from diseased plant tissues to healthy ones.
This process becomes rapid under conditions of high humidity and moderate temperatures (15-22°C). Also, the disease often starts at high daytime temperatures (30-35°C), if conditions are very humid, and night temperatures are moderate (15-22°C). Similar weather in our country often occurs in late July-August. This period is precisely when late blight disease peaks.
It is known that the late blight pathogen does not live directly in the ground, but can overwinter in plant debris, including unharvested potato tubers. Tomato seeds may also be initially contaminated.
Often late blight “flies” onto tomatoes from infected potato plantings if they are located nearby (closer than 500 m). And if by this time the plantings are not protected with an appropriate fungicide, the weather is favorable for the development of the pathogen, and there is a lot of drip moisture on the leaf, then the rapid development of infection cannot be avoided.
Note!
In addition to tomatoes and potatoes, other nightshades are susceptible to late blight: peppers, eggplants, nightshade, petunia. Grapes, strawberries, and cucumbers are less commonly affected. Plantings of these plants can also serve as a source of late blight infection.
Chemical remedies
This group of fungicides has a suppressive effect on phytosporosis spores and limits the spread of the disease.
Khom contains copper chloride and retains toxicity for 5-7 days. Often used for preventive purposes.
Ordan is a synthesized oil-based fungicide, highly toxic.
Quadris is a new generation drug with a wide spectrum of action and moderate toxicity.
What is late blight and what does it look like on tomatoes?
- Late blight first appears on the lower, older leaves in the form of gray-green watery spots without a clear outline. These spots quickly become brown, dry, often with a light green border of withering tissue. Gradually, the affected areas spread over all leaves.
- As the disease matures, a white coating of millions of spores forms on infected tissues.
- Dark brown spots develop on the stems and petioles, and a white fungal coating also forms on them. If the petioles are damaged, the leaf may fall apart into fragments.
- Dark brown “greasy” spots appear on affected tomato fruits. Initially, they are harder than the rest of the tissue, but they can also become soft and rotting - when putrefactive bacteria are connected.
- In rainy, cool weather, entire fields of tomatoes become brown and dry, as if after frost.
This is what late blight looks like on tomatoes (the photos below show lesions caused by late blight: spots, fungal plaque, spoiled fruit):
Lesions of tomato leaves due to late blight: brown spots with a gray-green border, spore growth is observed on the underside of the leaves under humid conditions
Black spots appear on the stems of tomatoes; in humid conditions they become covered with a white fluffy coating
Dark “greasy” spots appear on tomato fruits
Note!
Tomato fruits begin to rot quickly when affected by late blight. However, any unaffected part of the fruit is safe to eat, as the late blight pathogen does not produce a toxin.
Many of these symptoms are somewhat similar to other diseases that often affect tomatoes. And here it is very important to see the differences.
- For example, with Alternaria blight, dark spots are smaller in size and have a characteristic pattern in the form of concentric rings or a target.
- With septoria, the spots are small, often with a lighter center.
- Drought stress can also masquerade as late blight, producing large areas of dried tissue on the leaves. However, symptoms of drought stress always extend from the edge of the leaf, they lack the light green border of wilted tissue, and there is no white coating. In addition, no symptoms appear on the stems or fruits.
The difference in leaf damage with late blight (photo on the left) and Alternaria (photo on the right)
As a rule, all these “copycat” diseases affect only the tops or cause minor damage to the fruit. Although they may reduce the yield, they do not cause total loss. While late blight in just a few days can lead to the death of the entire plant, along with the fruits and the long-awaited harvest. This is a serious threat to both individual gardeners and commercial growers.
Unconventional methods
Many gardeners use folk remedies for late blight on tomatoes. They have been tested in practice and are quite effective.
Antiseptics: iodine, furatsilin, hydrogen peroxide provide a disinfectant. The solutions are used to wipe the fruits removed from the affected plants.
Antifungal medications are diluted in a concentration of 1 tablet per liter of water. This method has become popular recently.
Wood ash, soda, and fermented whey change the acidity level. Soap is added to these solutions for better adhesion: 2 tablespoons per bucket of water.
Reviews from gardeners
Valentin Konstantinovich:
Late blight is a complex disease that is not easy to treat, especially in open ground. After I first noticed it on tomatoes, I was unable to completely save the crop. Therefore, I began to prepare for the next season in the fall. He removed and burned all the leaves, weeded the garden, and watered it with copper sulfate. The next year, in the spring, I repeated the cultivation of the land. Then I sprayed the seedlings and as a result the late blight receded.
Varvara:
I recommend using only folk remedies, since they do not poison the human body, but help get rid of it just as well. I used garlic solution and sour milk. Of course, you need to spray regularly, but the result is worth it - all the bushes are green, and the fruits do not rot.
