Spots on tomatoes - cladosporium and late blight: how to distinguish and cure
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SPOTS ON TOMATOES - REASONS, PHOTOS, DIFFERENCE, NAME AND DESCRIPTION OF THE FIGHT
I will go into the greenhouse and admire my tomatoes: emerald greens, flowering brushes, ripening fruits - what a joy for a gardener! However, you should not relax, along with the ripening harvest, various diseases "ripen". The most common ones are - cladosporium and late blight... And it is desirable to know them "by sight".
CLADOSPORIOSIS (brown spot) appears approximately in the middle of the garden season, and even earlier in cold and rainy summers. The disease develops rapidly in high humidity. And it is not always possible to notice it in time. Initially, a whitish, mildew-like coating appears on the underside of the leaf. It later turns brown. This mushroom does not affect the fruits, photosynthesis is greatly weakened, the plants stop developing.
Without protection, sooner or later all plants in the greenhouse will be affected. True, to varying degrees, there are some varieties and hybrids that are more resistant to the disease. How can the spread of the disease be slowed down? Removing diseased leaves. Plants are better ventilated, less over-airing each other.
Do I need to remove the lower leaves from a tomato if they are healthy? Yes, but this must be done carefully and in a timely manner. When green fruits have formed on the first lower brush and have reached (if the characteristics of the variety or hybrid allow) the size of a chicken egg, it is time for an artistic shearing of plants, no more than 2-3 leaves can be removed per week. If you cut off all unnecessary at once, the plant will experience stress and instead of laying new brushes and pouring fruits, it will begin to actively grow new leaves and stepsons. It also happens that a variety that, before removing the leaves, laid flower brushes after 1-2 knots, after execution can lay another brush only after 3-4 knots. Time will be lost, harvest reduced.
Left: Sporulation spots of cladosporiosis appear fluffy. Right: Late blight on tomato leaves
When the fruits are formed on the second brush, the leaves are removed before it - also gradually, and over time - up to the third brush, etc. As a result, by autumn the plants have greenery only on the "crown", they are well ventilated, and the tomatoes continue to ripen.
In the second half of summer, a more dangerous disease for tomatoes appears in our area - late blight (there are no varieties and hybrids resistant to this disease, although there are tolerant ones. - Ed.). As a rule, potatoes in the open field are the first to get sick. This means that the time is coming for tomatoes too.
Phytophthorosis first "burns" the leaves, and then the fruits. On the leaves noticeable black rounded spots are formed, and on the fruits - barely noticeable foci reminiscent of “cellulite”, small tubercles, colored a little lighter than the rest of the fruit. Then the affected area darkens and grows throughout the tomato. Such fruits will no longer ripen, and they cannot be used for food.
I noticed that tomatoes powdered with dry ash are much less likely to be affected by late blight. And before eating, the ash can be easily washed off the fruit. But nevertheless, if the disease has begun, then the insidious disease will quickly destroy a significant part of the crop. Therefore, at the first signs of late blight, I remove green fruits, laying them out for ripening in the house. I preheat the fruits - immerse them for 1-2 minutes in water heated to 60 °, and then immediately transfer them to a bucket of cold water for 5-10 minutes. This can significantly reduce the number of late blight spores. After drying, I put the tomatoes on the boxes in one layer. Despite the fact that after warming up they rot less often than without it, I regularly inspect the stocks and remove spoiled fruits. You can't compost them, I bury them deep under the bushes (or even better, burn them.
PHYTOFLUORA ON TOMATO FRUIT
SPOTS ON FRUITS can also appear with sunburn. But in this case, the leaves are healthy, and on the fruits that have reached technical ripeness, watery light spots are formed on the sunny side, drying out and sinking over time. Not only low-leafed varieties are prone to burns, but also those with a lot of foliage. It is enough only to remove a significant amount of leaves at a time. Sometimes burns appear on plants that have fallen under the weight of the fruit. A secondary infection may develop in the affected areas.
Sunburn prevention measures are logical and simple. When feeding and watering the plants, it is important to provide them with optimal conditions for the development of green mass, and the leaves must be cut off one by one. In the southern regions, they do it simply: they shade the plantings.
See also: Tomato-cladosporiosis or brown spotting - resistant varieties and control
7 STEPS OF PROTECTION AGAINST CLADOSPORIOSIS AND PHYTOFLUOROSIS
Since both cladosporium and late blight develop at high air humidity, I use such techniques to reduce it.
1. With the onset of stable heat (in our country - from mid-June), when the threat of frost has passed, I do not close the doors of the greenhouse at night. This prevents condensation from forming on the walls of the greenhouse and the air is constantly circulating. The neighbors are very sorry for my plants, they say, they are cold at night. However, in their greenhouse, which they carefully close every evening, diseases start much earlier and run more violently.
2. A non-woven fabric stretched under the "roof" of the greenhouse gives a very good effect. It traps condensation drops. And the water on the leaves is what is needed for the development of diseases. That is why it is categorically unacceptable to water tomato bushes with sprinkling (from a watering can to a bush). If the tomatoes grow in open ground, I cover them in arcs with a film, making a roof impervious to water. From the end sides (and better from the sides) I leave the greenhouse open - for ventilation. Non-woven material in such a situation is less effective - in part it still allows moisture to pass through, which is highly undesirable in case of prolonged cold rains.
IT IS NECESSARY TO REMOVE THE LEAVES gradually, 2-3 PER WEEK IN ORDER TO INCLUDE STRESS IN THE TOMATOES
Sometimes, entering the greenhouse early in the morning, you can see that a drop of liquid hangs on each leaf. This phenomenon is called guttation. The root system of a tomato is powerful and can extract moisture from great depths. Abundant watering, especially in the evening, promotes the active absorption of water by the roots. At night, the evaporation of water from the leaves is reduced, and droplets of moisture (sometimes with an excess of salts) are released through the stomata of the leaves. Is guttation harmful? Probably not. This is a natural phenomenon. However, having noticed a similar symptom, you can water the plants a little less often. Just try not to allow sharp fluctuations in humidity: the fruits may crack and will no longer be stored.
H. For watering, I use plastic bottles dug into the ground with a volume of 1,5-2 liters. I cut off their bottoms, make holes along the walls, and close the neck with a cork. I bury the resulting funnels in the soil, leaving 3-4 cm above the surface. Thus, when watering, all moisture and fertilizers go directly to the roots of the plants. I mulch the garden with dry grass.
4. It is important not to thicken the planting. Adequate illumination, coupled with free air circulation, is only beneficial for plants. I plant tomatoes in a staggered pattern at a distance of 50 cm from each other. I lead in two trunks (no more) and be sure to remove the stepsons.
IN THE OPEN SOIL OF PHYTOFLUORA ON TOMATOES ARISES EARLIER AND DEVELOPES FASTER
5. Plants weaken under heavy load of fruits. To keep them in good shape, I use feeding and stimulants. Before planting, I fill the soil with vegetable-peat compost (but without fanaticism, otherwise the plants will fatten). In principle, I don't use manure compost here. Periodically I feed the plants with infusions of nettle, onion husks, ash and humates. From time to time I spray the leaves with succinic acid and microfertilizer, which improves tying, containing magnesium, boron and calcium.
Tomatoes need calcium! With its deficiency (as well as with soil drought), the fruits can get sick with apical rot. The disease is non-infectious, but it is quite capable of depriving you of your first harvest. Varieties with elongated and plum-shaped fruits are especially often affected. And with an excess of potassium, top rot can appear even at the end of summer.
To protect against diseases, tomatoes have been sprayed with biological products since the end of June. They have no healing effect, but they can prevent infection. Chemical preparations give a more visible effect in the treatment of already diseased plants, however, they are also more toxic for the harvest, and a waiting period must be observed when the fruits cannot be harvested and consumed.
6. When signs of late blight appear on the potatoes, I tighten the window of the greenhouse with tomatoes with a non-woven material. I close the doors at night, and the window remains open, but with a "curtain".
7. Every autumn I always remove all plant residues from the greenhouse, change the topsoil and wash the walls of the greenhouse with the addition of washing powder. I even burn the ropes that were used to tie up the tomatoes. After all, fungal spores can also persist on them.
Note: Synthetic detergents negatively affect the acidity of the soil. have a detrimental effect on the soil mesofauna and can contribute to the accumulation of heavy metals and nitrates in crop products. Therefore, to wash the walls of the greenhouse, it is better to use not washing powder, but a solution of household or green soap, and for disinfection - a solution of copper sulfate or phytosporin, and then rinse with clean water.
It is justified to use sulfur checkers only after severe outbreaks of disease and in no case should they be abused. Indeed, during combustion, sulfurous anhydride is formed, which penetrates everywhere (which is why sulfuric acid is considered the most effective way of disinfecting greenhouses and cellars). But the anhydride, combining with water vapor, turns into an unstable compound - sulfurous acid. It eats away at the zinc coating of greenhouses, leading to the rapid appearance of rust on all metal structures. There were cases when polycarbonate after processing became darker.
Reference by topic: Stains on cucumbers - causes and struggle (photo)
SPOTS ON TOMATOES - VIDEO
© Author: O. MELNIKOVA Arkhangelsk region
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We have been fighting tomato cladosporiosis for several years. The harvest is poor, most of the tomatoes can be harvested (they are not affected), but there are a lot of spoiled ones. I heard that it is useless to apply spraying or any other methods of treatment, since the pathogen remains in the ground for many years. Is it so?
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For many years it has not been possible to protect tomatoes from late blight. I tried to process both Ridomil and HOM - it does not help. As a physician, I know that fungal infections are afraid of acid. Maybe you can spray the diseased bushes with a vinegar solution? If so, how do you do it?
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- I do not recommend using vinegar in the fight against late blight: it is a rather aggressive agent that can destroy plants. And there are no other remedies that could completely cure the disease. Therefore, do not wait for the first signs of late blight to appear, but regularly treat the plantings with drugs against the disease or folk remedies. The first time is usually sprayed with preparations of contact action no later than 14 days after planting the seedlings.
Then the bushes are treated with fungicides or biologicals every two weeks. Chemicals to combat late blight are no longer used 3 weeks before the expected harvest. At this time, you can use Eco-sil (15 drops per 3 liters of water), a solution of skim milk (100 ml per 1 liter of water) with the addition of one or two drops of iodine, a solution of milk whey (1 liters per 5 liters of water) with adding 10 tsp. iodine. In addition, Furacilin (1 tablets per 10 liters of water), as well as Trichopolum, Metronidazole (10 tablet per 1 liter of water) are popular among gardeners.
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I perfectly understand your concern about cladosporiosis in greenhouse tomatoes, because I have been trying to cope with this problem for many years in the same way. And in the same way, I went the only way that experts advise - I found varieties resistant to this disease on the Internet.
I went to the seed store with the list and was so glad that there were as many as eight varieties! Of these, three varieties of tomatoes passed the test perfectly: Eupator, Raspberry Elephant and Ural-Super.
Unfortunately, you do not write which varieties of tomatoes, according to your results, have confirmed their resistance to cladosporiosis. But now I will still look for them further, because there is no other way.