Late blight is a real scourge of plants in the nightshade family. Late blight of tomatoes begins on separate bushes and quickly covers all plants. This is one of the most unpleasant phenomena, which almost every year brings a lot of inconvenience to summer residents and gardeners. If you do not process each bush in advance, then you can forget about homemade tomatoes. Blown tomatoes are gradually covered with brown spots. First, the leaves suffer, then the stems, the fruits. In just a few days, the entire crop dies.
Photo of a tomato affected by late blight:
Signs of tomato late blight
Phytophthora spores, spreading to the plant and soil, spread rapidly. Within 3-16 days, the development of the disease begins.
Since plants are affected at different time intervals and unevenly, the initial stage of late blight can go unnoticed.
Over time, dark spots of brown or grayish-brown hue appear on the leaves and stems, which quickly spread.
In conditions of high humidity on the underside of the affected leaves, a white fluffy coating appears on the stems.
Dark blurry spots form on the fruits, which can merge with each other, gradually spreading over the entire surface. The fruits are often deformed, acquiring an irregular shape.
At first, the fruits are solid, but with the development of the disease soften - decay begins. As a result, the fruit rots completely, acquires a characteristic sharp unpleasant odor.
Late blight can also occur during ripening (maturation in storages) of green fruits collected before the onset of symptoms of late blight. Damage to crops without the use of fungicides, depending on conditions, can exceed 70%.
Blight is usually transmitted to tomatoes from closely spaced potato plantings: spores are washed off with water into the soil and they spread to the surrounding territories. Or tomatoes become infected from infected tubers left in the ground after a previous crop susceptible to late blight. If late blight of potatoes is detected late blight, within 2-3 weeks it also occurs in tomatoes.
As a rule, the development of late blight is provoked by prolonged rains (longer than 2-3 days) with a concomitant decrease in night temperature. The difference between day and night temperature is 8-12 degrees. Such differences contribute to abundant dew, which further increases humidity, including directly on plants. The combination of all these factors creates the most comfortable conditions for the propagation of phytophthora spores.
Favorable conditions for the development of the fungus are high humidity, low air temperature, fogs. In conditions of dry sunny weather late blight does not develop at all.
In order to keep the plants healthy for as long as possible, it is necessary to maintain large intervals between them when planting, avoiding thickening the rows, periodically remove the lower coarsened leaves, and mulch the soil with rotted hay. It is best to water plants of the nightshade family under the root so that they do not get completely wet.
Prevention and treatment of tomato late blight
I subtitled words about the treatment of tomatoes for late blight. But I must admit that it practically does not respond to treatment. You can only delay, slow down its development, or prevent its appearance. That is, the main thing here is preventive measures.
In the event that late blight is clearly visible to the naked eye, most of the crop, alas, will die, so you need to constantly monitor the weather forecast. As soon as the air temperature drops below 15 degrees Celsius, it rains more often, you immediately need to spray.
After detecting the first signs, it is necessary to remove the affected leaves in a timely manner, burn them, remove the fruits in green for ripening, rinsing them thoroughly, disinfecting in water at a temperature of 60 ° C for 2-4 minutes. Spraying should be carried out regularly with anti-late blight drugs. This can save a certain part of the crop.
Fungicides help prevent or delay the development of late blight - these are chemical or biological drugs to combat fungal diseases. Biological - Fitosporin (5 g per 10 liters of water), Ecosil (15 drops per 3 liters of water). Chemicals - Bordeaux liquid, Ridomil Gold MTs, Tatu, Quadris, others.
Using chemicals, pay attention to the waiting period written in the instructions, after which the effect of the chemical product is neutralized - the fruits can be eaten.
To prevent late blight, you can immediately sprinkle it with milk serum immediately after transplanting the seedlings into the greenhouse or open ground. The serum contains lactic acid, lactic acid bacteria that inhibit the growth, reproduction of fungal spores of late blight. But you need to do this regularly - every 7-10 days. There is evidence of many gardeners that one whey, without the use of chemical protective agents, has been saving their tomatoes from late blight for several years.
I want to warn you that homemade or market whey with a high fat content should be diluted with clean water. The fatter the whey, the more water you need to add. Milk fat clogs the pores of plants, they have nothing to breathe. Sometimes it is enough to dilute 1: 3, sometimes 1: 1.
The same applies to homemade whey obtained from long-sour milk - it contains a lot of acid - you can get an acid burn of leaves.
I use a convenience store, sometimes I buy cottage cheese from sellers in the market. I try the store taste - if not acidic, and the percentage of fat content is not more than 1%, then I do not dilute it.
By the way, whey contains trace elements necessary for the development of tomatoes. This is an excellent top dressing.
About two times per season - once for seedlings and once during the flowering period - I add a few drops of iodine to the serum for spraying. The calculation is: 10 drops of iodine per 10 liters of serum. Iodine will not protect tomatoes from late blight, but will help more abundant, friendly fruit setting.
Summer residents, gardeners with experience recommend processing the bushes every 2 weeks. And during frequent rains at least once a week. Spraying should be done in the evening after sunset, or early in the morning. In addition to leaves, stems, fruits, it is advisable to water the soil under the plant with fungicide, so that the fungi living in the ground die, do not multiply, do not develop.
The risk of tomato disease with late blight increases if crops are planted in soil with a high nitrogen content. In such cases, it is recommended to additionally apply fertilizers with the addition of potassium and phosphorus, which enhance immunity. Eggplant and pepper are sometimes affected by late blight, so they should also be processed, like tomatoes.
It is worth considering that phytophthora has the property of adapting to chemicals, which is why you have to alternate at least 2 drugs, which are based on various active substances.
They say that tomatoes can be protected from late blight by a copper wire entwined around the plant. Or a copper wire ring stretched through a stalk. But I myself did not do this, since I doubt that the punctures of the stem for the plant will be harmless.
When late blight has already infected tomato leaves by 60-70% - the fruits urgently need to be saved - treat them with a solution of sodium chloride (1 kg per 10 liters of water). But this is the most extreme measure. Used to save the fruits. Salt will kill all infected and healthy leaves - late blight will not pass on to the fruit. And those who managed to get involved by this time will be able to ripen.
Since the fight against already infected plants is ineffective, the damage to the crop can usually only be partially reduced, and maximum attention should be paid to preventive measures.
To ensure maximum protection of the culture from late blight, a number of agrotechnical measures should be carried out:
- Choose for planting late blight resistant tomato varieties.
- Observe the conditions for proper crop rotation: crops subject to the same diseases should be planted in the same place no sooner than after 3-5 years.
- Observe the spatial isolation of crops susceptible to late blight.
- Observe the required distance between the holes when planting seedlings: for early compact varieties, at least 30 cm; for later - 40-50 cm; the distance between the rows is not less than 70 cm.
- To prevent late blight of greenhouse tomatoes, do not plant open ground plants near greenhouses.
- With an increased level of humidity in the greenhouse, provide the plants with ventilation, remove excess shoots, lower leaves in time.
- Use only healthy seed for seedlings.
- If signs of late blight are detected, potato tops should be treated with special fungicides for planting tomatoes.
- Treat with fungicides tomato planting before the start of the lingering rainy season.
- Time to remove weeds, lower leaves, conduct pinching.
- Do not exceed the norm of nitrogen fertilizers for tomatoes, since an excess of nitrogen reduces the resistance to late blight disease.
- Watering is done early in the morning under the wells, to prevent moisture from entering the plants.
- Timely make fertilizers containing phosphorus, potassium to increase the resistance of tomatoes to the disease.
- Choose for planting early, early ripening varieties of tomatoes that ripen before the rainy season and, accordingly, until favorable conditions arise for the development of late blight.
- In regions with high humidity, carry out early spraying of tomatoes with systemic contact fungicides, which can significantly reduce the risk of late blight.
Fungicide Strobi will help protect tomatoes
Every gardener, a lover of tomatoes, knows how much rain and cold dew do at the end of summer, like plants in the open ground, also in the greenhouse.
Since tomatoes are my favorite garden crop, I plant a lot of them, at least 100 bushes. In recent years I have used various protective equipment, so I want to share my opinion, experience with the use of the Strobi fungicide.
I must say right away that this tool is strong, effective. Of the shortcomings, it can be noted that the Strobi drug is toxic. Before that I used and still apply, Fitosporin - I was also pleased. But I like to experiment, so I decided to try Strobi this year. The beginning of the garden year was very wet, I was afraid that my tomatoes would not stand the coolness, frequent rains, they would get late blight. But nothing happened. Applied Strobi only once - late blight.
Of course, I cut off all the leaves on the tomatoes that I did not like, with spots, dry tips. I didn’t even regret some of the fruits.
Now I’ll tell you how I prepared the solution. The Strobi bag contains small granules - almost powder. One bag (2 g) is enough for a bucket of water. This solution is enough for me to spray 100 adult bushes of tomatoes.
First, a film appears on the surface of the water when preparing the solution, but with constant stirring, it disappears.
The instruction warns of safety measures when preparing the solution - because it is toxic. I cooked it with gloves and glasses to avoid accidentally dropping drops on the skin, mucous membranes.
The duration of the protective action of the Strob is 10-14 days. The substance decomposes well in the soil and has minimal toxicity to animals. This is good, because in the garden I have free walking hedgehogs, neighbor cats who like to relax between the beds in the shade in the summer heat.
I try to spray not only the upper surface of the leaves, but also the lower.
The biggest advantage of Strobi is that it is effective at low temperatures - it can be sprayed even on leaves wet from rain. Moreover, it will be useful both at the beginning of the disease, as well as in its midst. But just cold, humid weather creates the conditions for the development of late blight. I do not know other drugs with such properties. It is hoped that this drug will be able to defeat late blight.
Strobi is also used on other plants: apple, grapes, pears, flowers (especially roses). But for now, I only saved them tomatoes. And I did it.
And the minus of this drug is only one - after all, it is chemical.