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Late blight is a fungus that can infect potato, peppers, eggplants and, of course, tomatoes, causing a disease such as late blight. Phytophthora spores can travel through the air with the wind or be contained in soil. In a “dormant” state, they fall on the leaves of plants and rest there until favorable conditions arise, after which they actively reproduce, causing harm to tomatoes.
More often you can find late blight on tomatoes in open ground in autumn, during prolonged cold spells or after heavy rains. Fungi develop very quickly; tomatoes become infected within a few hours. That is why it is necessary to use and know preventive measures to combat the disease. The appearance of external signs of late blight infection on the leaves and trunks of tomatoes indicates an active stage of fungal proliferation. At this stage, various chemicals and improvised means can be used to save tomatoes.
Causes of infection
Strong, healthy tomatoes in conditions with optimal temperature and humidity, regular, moderately abundant watering have sufficient immunity to resist late blight. And the fungi themselves cannot reproduce in such conditions. Their active division and distribution occurs in an environment with high humidity and relatively low temperature. Such conditions are typical for the autumn period, but can overtake the gardener in the summer.
The following circumstances can provoke the division of late blight fungi:
- weather conditions with prolonged rains and cold temperatures;
- frequent and sudden changes in temperature;
- lack of micronutrients in the soil;
- frequent, abundant watering;
- high concentration of nitrogen in the soil;
- growing tomatoes in wetlands;
- growing tomatoes in close proximity to other nightshade crops;
- dense planting of tomatoes without observing the recommended distances;
- growing tomatoes in soils with neutral acidity or a high concentration of lime in the soil.
Of course, growing tomatoes in open ground, the gardener cannot influence the weather conditions in any way, but provide some protection from late blight for tomatoes, it is still possible by choosing sunny, windless areas of land for cultivation, where groundwater is located far from the surface. Distances between bushes When planting seedlings, there should be enough space to ensure normal air circulation. Condensed plantings contribute to the rapid spread of fungal diseases through contact of tomato leaves and fruits.Particular attention must be paid to the choice of “neighbors” for tomatoes: peppers, potatoes or eggplants should not be planted close to tomatoes; it is better if it is, for example, garlic. In addition to the above growing conditions, there are other preventive methods for protecting tomatoes from late blight.
Prevention of late blight
Some tomato seed manufacturers offer varieties resistant to late blightHowever, you should not rely on such a “trick”. There are no varieties with absolute protection against late blight. When purchasing seeds, you must independently take care of protecting the tomatoes and the future harvest at the stage of sowing seeds for seedlings:
- Phytophthora spores can be destroyed from the surface of grains by soaking them in a special antifungal solution, for example, a solution of the drug “Fitodoctor” or “Fitosporin”;
- Phytophthora spores can also be contained in the soil for growing seedlings, so before sowing seeds it must be disinfected with boiling water. Heating in the oven or over an open fire is also effective;
- containers repeatedly used for growing seedlings must be treated with a solution of copper sulfate.
If you follow these simple growing rules, tomato seedlings are reliably protected from disease, however, when planted in open ground, the likelihood of infection with late blight fungi increases, which means you need to resort to additional preventive measures to protect tomatoes.
Outdoor protection methods
Before planting tomatoes in the soil, the holes should be spilled with a solution of boiling water with the addition of potassium permanganate. Prevention of late blight on tomatoes in open ground may involve treating the bushes with special biological products or folk remedies.Among the biological products, the most effective are “Zircon” and “Fitosporin”. These biological products should be diluted with water in accordance with the instructions, for example, for preventive spraying of tomatoes, you need to add 2-3 tablespoons of “Fitosporin” to a bucket of water. This volume should be sufficient for processing tomatoes per 100m2.
Experienced gardeners often resort to traditional methods of protecting tomatoes from late blight:
- Spraying with saline solution. You can prepare it by adding 1 cup of table salt to a bucket of water. After mixing, the solution is sprayed onto the tomatoes, as a result of which the salt covers the tomato leaves with a thick film, preventing late blight spores from penetrating their surface.
- Spraying with ash infusion. Ash is not only a microelement fertilizer for tomatoes, but also an effective means of protection against late blight. You can prepare an ash solution by adding 5 liters of this substance to a bucket of water. After mixing, the product is infused for 3 days, then 40-50 g of grated laundry soap are added to it. Ash, like saline solution, protects tomatoes by covering the leaves of the plants with a film.
- Treatment with fermented kefir or whey. These products are diluted with water in a ratio of 1:9 and used to spray tomatoes.
In addition to the above methods for open ground, there are other ways to protect tomatoes, based on the use of garlic, copper wire, and iodine. An example of using folk remedies for late blight on tomatoes can be seen in the video:
However, it is worth understanding that such products can protect tomatoes from late blight, but cannot cure an already damaged plant. Therefore, they should be used regularly for prevention once every 10 days.
Rules for caring for tomatoes
The risk of late blight infection of tomatoes can be reduced by following certain rules for growing and caring for plants:
- It is impossible to grow tomatoes for two seasons in a row in the same place. In the place where nightshade crops previously grew, it is possible to grow tomatoes only after 2-3 years. It is better to plant tomatoes in places where cauliflower, beets, carrots, onions, and cucumbers previously grew.
- It is necessary to water tomatoes early in the morning or after sunset exclusively at the root, since the accumulation of water in the axils of the plant provokes the development of late blight.
- On days with high air humidity, it is recommended to refrain from watering and only loosen the soil. It is worth noting that mulching, which helps retain moisture in the soil, is also considered a preventive measure in the fight against late blight.
- Healthy tomatoes have a certain immunity to late blight, so it is necessary to regularly monitor their balanced diet, fertilize them with phosphorus and potassium. The use of fresh manure and other fertilizers with a high nitrogen content for tomatoes is undesirable.
- By correctly forming tomato bushes and pinching, you can avoid dense plantings and improve air circulation between the fruits and leaves of tomatoes.
Thus, by following simple rules for caring for tomatoes and periodically carrying out preventive treatment with biological products or folk remedies, you can reliably protect plants and successfully fight late blight even in weather conditions favorable for its development.
Signs of late blight
Many gardeners know the signs of late blight, but, unfortunately, they are the visible result of already active fungal activity. In the early stages of infection, it is almost impossible to detect signs of late blight on tomatoes.
Symptoms of late blight appear a few days after infection. So, you can understand that tomatoes are infected by the following signs:
- Small spots appear on the inside of the leaf. Over time, they appear through the entire thickness of the leaf plate and acquire a dark, brown tint. As late blight develops, the leaves dry out and fall off;
- Dark and then black spots appear on the main trunk and shoots of the tomato. The affected areas begin to dry out;
- Tomato ovaries turn black and fall off;
- Dark spots appear on the fruits, which subsequently turn into wet, rotten spots.
An attentive owner should regularly inspect tomato plantings in order to detect and eliminate the problem in the early stages. In this case, it is worth paying attention to the factors that provoke the disease: cold rains, sudden changes in weather conditions, and others. It is after such changes that we can expect the development of late blight, which means that it would be useful to treat the bushes with preventive protection products.
Treatment of tomatoes for late blight
If preventive measures to protect tomatoes from late blight were not carried out or did not give the expected result and signs of the disease appeared on the leaves and trunks of the plant, then it is necessary to begin treating the plants as quickly as possible. To do this, you can use special chemicals or some available substances.
Chemicals
There are various chemical preparations for late blight with high effectiveness. Among them, Infinito, Metalaxyl, Ecopin, Ditan M45 and some others should be highlighted. These substances are diluted in water according to the instructions and used to spray tomatoes.
It is worth noting that all these substances are dangerous to human health, which is why it is preferable to use them before the fruit ripens. If chemicals were used during the ripening of vegetables, the fruits should be eaten no earlier than 3 weeks later. During this time, the drugs cease their activity.
Handy means of protection
In the fight against late blight, especially during fruit ripening, it is recommended to use traditional but effective methods for treating tomatoes:
- Antifungal and antiviral medications, such as “Metronidazole” and “Trichopol” have long been used to combat late blight. Tablets are easy to find in any pharmacy, their cost is affordable. Prepare a solution of these antibiotics by dissolving 20 tablets in 10 liters of water.
- Copper sulfate can be used as a preventative remedy and for treating tomatoes against late blight. It is used in the form of an aqueous solution by adding 2 tablespoons of the substance to a bucket of water. This remedy is effective, but it cannot be used often.
- Based on boric acid You can prepare a remedy for treating tomatoes against late blight. The substance is diluted in water in a ratio of 1 teaspoon per bucket of water.
- Spraying infected tomatoes 1% potassium chloride solution can overcome the disease. You can find the substance at the pharmacy.
The above methods for treating tomatoes are quite effective. However, chemicals must be used with extreme caution; the fruits after such treatment should be kept on the bush for at least 3 weeks and washed thoroughly before use. The means at hand do not pose a danger to humans, but to achieve high efficiency they must be used several times with an interval of 7-10 days.
Actions with damaged tomatoes
When the treatment of tomatoes infected with late blight has been carried out, care must be taken to preserve the still unripe tomatoes and the already ripening harvest:
- Remove and burn affected tomato leaves;
- Ripe but blackened tomatoes will most likely have to be thrown away or damaged parts of the fruit should be cut off and “clean” tomatoes used for canning;
- Unripe tomatoes, but damaged by late blight, should be removed from the bush and heated in water at a temperature of 600C. To do this, you need to pour heated liquid into a basin or bucket and lower the tomatoes into it. As the water cools, change to warm. After complete heating, the late blight fungus in the fruits dies, which means they can be placed in a dark place for ripening without fear of the development of rot. Also, unripe tomatoes, after trimming the damaged parts, can be used for canning;
- It is impossible to put tops damaged by late blight on compost, this will contribute to the preservation of the fungus and infection of plants next year;
- It is possible to collect seeds from infected tomatoes for sowing next year only if they are treated with antifungal drugs before sowing in the ground.
Let's sum it up
Thus, it is better to fight late blight at the “distant approaches”, treating seeds and soil before sowing crops, properly caring for plants planted in open ground and regularly carrying out preventive measures to protect plants from this disease. In case of infection, it is very important to detect the problem in a timely manner and remove damaged leaves and fruits of tomatoes and treat the bushes with special substances. Vegetables that have been hit by late blight should not be immediately thrown away, since with proper subsequent processing they can be partially eaten in canned or even fresh form. In general, the fight against late blight requires attention and knowledge that will help defeat the “enemy.”
