Fungal infections can destroy all the work of a gardener. But tomato cladosporiosis, control methods and drugs against which are known and available, can be prevented or cured when the first signs appear. The disease spreads in the second half of summer, and in Russia it mainly affects greenhouse tomato plantings.
Ideal conditions for fungal development are found in a greenhouse or a warm, humid climate. The causative agent of brown spot, as cladosporiosis is otherwise called, requires a humidity of about 80% or higher, and the air temperature must reach +25°C. The fungus remains in the greenhouse or on the plantation where nightshade varieties that are not resistant to infection were grown.
Spores of a pathogenic fungus can be transferred with irrigation water, on the clothing of a vegetable grower caring for plants, and even with the help of air flow in a draft. On a diseased plant, peculiar bodies - conidia - are formed. They are filled with spores and can persist for 10 months.
If the cleaning of the greenhouse in the fall was carried out without special care, and the room was not disinfected, then the spores are quite capable of overwintering safely and awakening when conditions favorable for them occur.
The fungus has the ability to change. Therefore, even some varieties that have genetic resistance are sometimes affected by new strains of the infectious agent. Plants that do not have immunity to the disease suffer from infection every year, creating the basis for the persistence of spores on the site.
Signs of brown spot disease
Tomato cladosporiosis, or brown leaf spot, affects tomato bushes approximately in the middle of the growing season, when they bloom and begin to bear fruit.
Symptoms of the disease are easy to notice with the naked eye:
- Small yellow-green spots of irregular shape, with blurred edges, appear on the surface of the leaves. This symptom usually does not cause concern for an inexperienced summer resident. On the underside of such a leaf you can see a light coating, which is a colony of microscopic fungi.
- As the disease develops, the spot turns yellow and then turns brown, the reverse side of the leaf also acquires a similar shade, and the colony of fungi becomes velvety. At this time, new spores are released, which infect surrounding plants and spread throughout the plantation.
- The leaves begin to lose shape, curl, turn yellow and dry out. Affected foliage falls off the tomato bush, leaving bare stems.
Brown spot of tomatoes practically does not affect fruits and stems. Only the smallest ovaries can suffer from this disease, but its danger lies in something else. Due to the loss of leaves, the process of photosynthesis in tomatoes practically stops. Under these conditions, both flowers and already formed green fruits die. The gardener will be able to harvest only those fruits that had time to ripen before the disease spread.
In order not to lose the harvest, you need to take preventive measures, plant tomatoes resistant to cladosporiosis, or treat infected bushes as soon as the first signs of the disease become visible on them. For this purpose, fungicidal preparations have been developed that destroy the fungus. At the initial stage of the disease, proven folk remedies can also help.
How to treat and prevent the spread of cladosporiosis?
Traditional methods of combating the disease are relatively harmless to the owner of the site, but do not always have the desired effect. When using them, you can simply waste time during which the fungus has time to spread, and it will be more difficult to treat the disease.
For processing plantations using traditional methods, we can recommend the following:
- 15-20 drops of pharmaceutical tincture of iodine are diluted in 0.5 liters of milk. The liquid is mixed with water (5 l), the resulting solution is used to spray plants. Treatment is carried out every 2-3 days until signs of the disease completely disappear. The method helps only at the very early stage of the disease, when light spots appear on the surface of the leaf.
- Dissolve potassium chloride (30 g) in 10 liters of water, add 40 drops of pharmaceutical tincture of iodine. Spray the soil and tomato bushes generously with the solution 2 times a day (morning and evening) until the condition of the plants returns to normal.
- Sift the wood ash, take 300 g of powder and dilute it with 1 liter of water. Boil for 10-15 minutes, strain. Mix the resulting liquid with 10 liters of water and use the solution to spray tomato bushes and the soil around them.
- A good disinfectant is potassium permanganate. For spraying, prepare a pink solution. Treatment can be carried out 1-2 times a day if conditions are favorable for the development of fungus.
When using folk remedies, you need to monitor the condition of the tomato bushes: if the signs of the disease on the tomatoes do not disappear, you should worry about purchasing modern chemical and biological preparations and learn how to fight the infection using modern methods. The chemicals may be harmful to humans, but they are highly active against infection. By processing tomatoes according to the instructions, observing the timing of the use of drugs and personal safety measures, the gardener does not risk his health at all.
Among the broad-spectrum fungicides that are used not only against cladosporiosis of tomatoes, drugs such as Bravo, Captan, HOM, PolyHOM, etc. are used to treat the disease. After the first treatment of plants with these drugs, another spraying is carried out after 2 weeks to destroy the remaining spores mushroom.
At home, you can prepare a solution of copper sulfate and colloidal sulfur (sold in gardening stores). For 10 liters add 1 tbsp. l. vitriol and 3 tbsp. l colloidal sulfur. Both the plants and the soil around them are sprayed. The treatment is repeated after 5-7 days. The drugs are toxic, so you need to follow safety precautions:
- carry out spraying in special clothing;
- protect hands with gloves, and respiratory organs with a respirator or gauze bandage;
- if there is a draft, get rid of it or spray the product so that the air current carries the drops away from the person.
After processing the tomatoes, change clothes, wash your face and hands with soap, where drops of drugs may have gotten in. Pesticides cannot be used at the moment of ripening of tomatoes and 15 days before that.
In addition to fungicides, there are other drugs that can successfully fight fungi. They are practically harmless to people, but they must be used in accordance with the instructions:
- Fitosporin solution is prepared at the rate of 5 g of the drug per 10 liters of water. Treat the greenhouse 2-3 times with a gap of 2 weeks between sprayings.
- Fitolavin-300 is diluted in a ratio of 20 ml per 10 liters of water. Used for spraying.
- The modern drug Pseudobacterin-2 is prepared according to the instructions attached to it. The drug is able to fight various infections of garden crops.
The use of agricultural chemicals in case of plant diseases helps to quickly and reliably cope with the infection. But any disease is easier to prevent.
Prevention
The main preventive measure in a greenhouse is cleaning and disinfecting the premises in the fall. You can’t leave the stems of last year’s plants until spring. For disinfection, use Bordeaux mixture and a solution of vitriol, Fitosporin, freshly slaked lime, a hot strong solution of potassium permanganate and other means. They wash glass or plastic, spray or whiten wooden parts of equipment.
Other measures are also applied:
- the soil in greenhouse ridges needs to be changed once every 1-2 years;
- When growing tomatoes, ventilate the greenhouse more often;
- remove leaves from the bottom of the plants;
- When signs of disease appear, try to reduce the humidity (by airing) and prevent water from getting on the green parts of the tomatoes.
A good means of prevention is to grow tomato varieties that are resistant to brown spot. In 2018, you can plant hybrids Vologda and Bohema, Ural, Spartak, Olya, etc. These are modern productive varieties, specially bred by breeders.
To avoid introducing fungus into the greenhouse, it is recommended to grow seedlings yourself. Before sowing, seeds are treated by soaking in a solution of Fitosporin or potassium permanganate. By following simple rules of prevention, it is possible to completely protect plants from the disease.
The correct name for this disease is cladosporiosis, but almost no one uses this term in everyday life. Agree, the popular name “brown spot” is much easier to pronounce. The causative agents of this disease that is destructive to tomatoes are conidia.
These microorganisms are a type of fungus, but they are fundamentally different from it. Conidia, unlike simple fungal spores, grow directly on the mycelium and are almost weightless. They are easily carried around the site even by a light breeze. This is why the infection spreads so quickly from diseased tomato bushes to healthy ones.
Brown spot rarely occurs on tomatoes grown in greenhouses with an artificial microclimate. In ordinary greenhouses and garden beds, the fungus often affects tomatoes.
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Conidia of brown olive spot spread to tomatoes by air, through working equipment, watering, and with the help of insects and birds.
Conidia are extremely tenacious. They easily survive frosty winters and long droughts.
But it is not the causative agent of the fungus, but the fungus itself that affects tomatoes. He loves high ambient humidity and high temperatures. Here are the reasons why brown spots form on tomato leaves.
Manifestation of the disease and its consequences
Cladosporiosis on tomatoes usually appears before flowering. At this time, tomatoes accumulate strength for flowering and fruit set. A sign of the appearance of brown spotting is yellow plates on the upper side of the leaves.
Later, white spots appear in the form of plaque on the underside of the tomato leaves. These spots then begin to darken, and when the fungus has developed sufficiently, they turn brown. In addition, they turn into growths with a velvety surface.
As brown spot develops, the color and appearance of tomato leaves changes. They become lighter, and their shape becomes deformed. Then they turn yellow and fall off. The weakened leaves die first, and then the healthy leaves die under the onslaught of the brown spot fungus.
The loss of some foliage entails a lack of nutrients obtained by tomatoes from the soil. This, in turn, leads to weak flowering of tomatoes, which means a meager harvest.
Treatment options
Brown spot appears on tomatoes (see photo), how to deal with it? Cladosporiosis of tomatoes is treatable, but it must be started immediately as soon as the first symptoms of the disease appear. Among the ways to combat tomato cladosporiosis are chemicals or environmentally friendly folk recipes.
The most effective are such folk remedies for combating brown spot.
Garlic infusion with the addition of laundry or tar soap, you can spray not only tomato bushes that have white spots on the leaves, but also healthy ones. For the former, this remedy will have a therapeutic effect, and for the latter, it will have a preventive effect.
A weak solution of potassium permanganate For preventive purposes, tomatoes are sprayed or watered.
Tomato processing wood ash decoction alternate with watering with a manganese solution.
Please note that treatment with folk remedies is effective only if you detect brown spot on tomato leaves in time. If a tomato plantation is severely affected by brown spot, then it will be possible to save at least part of the crop only by using chemicals to combat the disease. Tomato cladosporiosis can be successfully treated with fungicides.
Protective equipment from the Bravo series Treat tomato bushes at intervals of at least seven, and preferably ten days.
Fitolavin Experienced gardeners use it only when there is significant leaf spot damage on tomato leaves. In greenhouses this product should be used no more than twice, and in beds 3-4 times
After treating tomato bushes with chemicals, the fruits can be eaten no earlier than 3 weeks after the last spraying.
Disease prevention
Even if you know how to deal with tomato cladosporiosis, the disease is easier to prevent. Nowadays, effective means have been invented to prevent fungal diseases of plants. Experienced gardeners advise using phytosporin, since he has proven himself to be the best. Water the soil with a solution of this product before planting tomato seedlings in the ground, so that later white spots do not appear on the leaves of the tomatoes. Spraying tomato bushes with a phytosporin solution is done at intervals of two weeks.
Yeast solution is also used to prevent the appearance of yellow spots on tomatoes.
Compliance with farming practices and the use of agrotechnical protective measures is an excellent prevention of the appearance of fungal diseases on tomatoes. Follow the rules of crop rotation in each area of your garden. It is necessary to alternate sowing crops on the site in accordance with agronomy recommendations.
- After harvesting, remove plant debris from the garden.
- When growing tomatoes in greenhouses, do not allow the air humidity in them to rise above 60-70%, and the temperature above 28 degrees.
- Try to plant tomato varieties in your garden that are highly resistant to fungal diseases.
- After harvesting, uproot all tomato bushes and burn them.
- Spray the empty beds with a solution of copper sulfate.
- It is impossible to grow tomatoes in one place for two years in a row, since brown spot spores remain viable for 10 months.
- Immediately tear off all tomato leaves with silver spots from the bushes and burn them.
- Water tomato bushes infrequently, but generously.
Tomato varieties resistant to brown spot
Treating brown spot of tomatoes is a bit of a hassle. You can grow varieties resistant to this disease that are not threatened by cladosporiosis of tomatoes, especially if they are planted in open ground. Breeders have developed quite a lot of such varieties.
Summer residents say that the varieties “Nasha Masha F1” and “Paradise Delight” have the most delicious fruits. The tomatoes of these varieties are very large, dense enough to be transported over long distances. In addition, Nasha Masha tomatoes are easy to care for. The variety bears fruit even if the bushes are in the shade of trees for most of the daylight hours. The “Paradise Delight” variety, on the contrary, requires careful care. Even if all the rules are strictly followed, the yield of this variety wants to be higher.
Stone fruit trees are mainly susceptible to brown spot disease. The disease is provoked by a humid environment and poor destruction of infected plant debris. Unlike white spotting, with brown leaf spotting, the focal areas of the lesions do not lighten, and through holes do not appear on them. When affected by the disease, the leaves simply wither and fall off.
Brown spotting of stone fruits appears on the leaves of plums and cherries in the form of small spots, the color of which can vary, as it depends on the type of fungus that has infected the plant. Spots on the leaves can be brown, yellow, framed by a dark border. Over time, small black dots - fungal spores - form on the spots on both sides of the leaf.
When cucumbers are affected, it is typical that first single, and then numerous brown spots of angular-round shape appear on its leaves.
In the middle, each spot has a characteristic light zone. Over time, a light transparent border forms around the spot on the leaf, which is clearly visible if you look at the leaf against the light. , grown in protected soil at high humidity.
Look at the photo: With brown spotting of a tomato, yellowish spots appear on the upper side of the leaf, under which a dark brown coating forms on the lower side. The spots can cover the entire tomato leaf, which leads to its further death. The spread of the disease is facilitated by high air humidity. The fungus overwinters on plant debris.
How to deal with brown leaf spot
To combat brown spot of tomato, it is necessary to promptly remove all plant debris from the garden beds and disinfect the greenhouses. It is important to maintain normal air humidity in greenhouses by conducting regular ventilation.
To combat brown leaf spot of stone fruits, it is necessary to remove the affected branches. Damage on young branches should be cleaned, disinfected with a 1% solution of copper sulfate (100 g per 10 liters of water), rubbed with fresh sorrel leaves and covered with garden varnish. Spraying with copper sulfate is recommended before the buds open.
Another way to combat brown spot is to spray trees with Bordeaux mixture (100 g per 10 liters of water) during the period of bud break.
It is necessary to remove all fallen leaves under and dig up the soil in the tree trunk circle, since this is where fungal spores overwinter. All affected leaves remaining on the trees must be destroyed.
When treating brown spot on cucumbers, it is necessary to maintain normal air humidity by regularly ventilating greenhouses. Sick plants must be removed promptly.
One of the most dangerous diseases. The causative agents of the disease are two species of fungi, similar in morphology and biology, but strictly belonging to their host plant. The causative agent of pear scab develops only on the pear, and the causative agent of apple scab develops only on the apple tree.
Fungi infect leaves, fruits, and less often shoots. Vague oily spots form on the leaves. Later they acquire a gray color and are covered with a greenish-brown velvety coating of sporulation. Severely damaged leaves dry out and fall off. The same spots appear on the fruits, but sharply limited, often with cracks. With early damage, the fruits become one-sided. On the shoots, especially pears, spots form on which the diseased bark then swells, cracks and peels off.
Scab pathogens overwinter in fallen leaves, and on young damaged shoots. In spring, the fungus forms black spherical fruiting bodies in which sacspores ripen. After rain, heavy dew or fog, sacspores are ejected from the fruiting bodies and carried by air currents. The ejection of sacspores occurs repeatedly and coincides with the period from the separation of buds to the end of flowering. Once on young leaves (or pear shoots), the spores germinate, forming a mycelium that penetrates the tissue of the leaves (or pear shoots). These are primary infections. A necessary condition for the germination of sacspores and their infection of plants is the presence of droplet-liquid moisture, so the disease develops more intensively in years when there is frequent rain, dew or fog in the spring. Young growing trees are most susceptible to scab. The first signs of scab appear before flowering or shortly after it.
On the affected green leaves, the fungus forms conidiophores, invisible to the eye, with conidiospores on them. Conidiospores are carried by the wind and infect healthy leaves and fruits (secondary infections). During the summer, the mushroom develops in several generations.
The following are severely affected by scab: Renet Simirenko, Delicious, Starkrimson, Korey, Melba, Borovinka, Mikentosh. Moderately resistant varieties: Jonathan, Idared, Pepin Litovskiy, Superprekos, Red Delicious. The following varieties are slightly affected: Winter golden Parmen, Snowy Calvil, Spartak, Janared, Kuban anise, Welsey, Wagner. Of the pear varieties, Winter Michurina is resistant to scab; Forest Beauty and Tonko-vetka are strongly affected.
Scab control measures
- Collecting and burning, composting or burying leaves in the fall after leaf fall. Spores do not form in leaves covered with soil. It is recommended to dig up the soil in the fall and carefully cover the fallen leaves.
- Thinning the thickened tree crown. Good crown ventilation is unfavorable for scab development.
- It is effective to spray apple and pear trees at the beginning of bud break (along the “green cone”) with 3-4% Bordeaux mixture or during the bud release phase with 1% Bordeaux mixture. After flowering, the trees are sprayed with 1% Bordeaux mixture or its substitutes (copper chloride, polychome). 18-20 days after flowering, the apple trees are again sprayed with copper oxychloride, polychome, Vectra or speed preparations.
Fruit rot, or moniliosis of apple and pear trees
It affects fruits, inflorescences and shoots of apple and pear trees.
The fungus overwinters in mummified (dried) fruits on the surface of the soil or on tree branches, in affected shoots and branches. In spring, spores form on such fruits. They are carried by the wind, causing primary infections. Brown spots (rot) form on the affected fruits, eventually affecting the entire fruit. White spore pads develop on the spots, arranged in concentric circles. Spores carried by the wind infect healthy fruits (secondary infection). By autumn, the affected fruits mummify, most of them fall off, and some remain on the branches. Affected flowers and leaves turn brown and wither, but do not fall off. In wet weather, grayish spore pads also form on them. The tops of the affected shoots dry out, the bark in the affected areas turns brown, shrinks, and cracks.
Over the summer, the mushroom develops in several generations. High humidity favors spore germination. Fruits that have mechanical damage (for example, leaf rollers, weevils, etc.) are more often affected. Once in a wound on the fruit, the spores germinate even without the presence of drip-liquid moisture.
Measures to combat fruit rot
- Cutting out and burning affected shoots after flowering.
- Regular collection and destruction of fallen affected fruits.
- Collecting from branches in autumn or winter and destroying mummified fruits.
- It is not recommended to store fruits with mechanical damage.
- Trees are sprayed with the same preparations and at the same time as against scab.
The fungus attacks the leaves, shoots, flowers and fruits of apple trees and sometimes pears.
The disease appears soon after the buds open.
The mycelium overwinters in the buds, on affected branches, and sometimes on leaves. In spring, the mycelium moves from the buds to the budding leaves, flowers, and shoots, where it forms conidia that are distributed by the wind. In the fruiting bodies (perithecia) that have overwintered on the branches, sacspores develop, which are released after rain and infect other plants.
A white felt coating of mycelium with numerous black dots of fruiting bodies appears on the affected parts of plants. Affected shoots are stunted in growth, their tops dry out, leaves curl and die. Diseased fruits are stunted in growth, often fall off, and rusty mesh and cracks appear on their skin.
Dry and hot weather contributes to the development of the disease. In winter, at a temperature of -20... -23“ C, the mycelium dies. Varieties susceptible to the disease: Renet Simirenko, Jonathan, Mekintosh.
Measures to combat powdery mildew
- Pruning and destroying affected shoots in autumn or early spring.
- Timely watering and tillage.
- The gardener should avoid applying large doses of nitrogen fertilizers.
- It is recommended to spray plants with azocene or colloidal sulfur.
- If the disease develops significantly, spraying is carried out at least three times: during the separation of buds, immediately after flowering (75% of the petals fall off), the third - two weeks after the second.
Fungal disease of the bark of branches and trunks of apple, pear, apricot and other fruit crops. A brown spot first appears on the bark, its edges thicken. Then the bark in this place dies, cracks and peels off, exposing the wood. Dead bark and wood turn black, and black tubercles of fruiting fungus appear on them. Leaves and fruits are also affected.
The fungus overwinters in the affected bark. Its spores disperse and infect trees throughout the warm period of the year. Infection is favored by the presence of cracks and mechanical damage to the bark. Older and weakened trees that do not receive proper care are more often affected.
Measures to combat black cancer
- First of all, pruning and burning of affected branches, uprooting and burning of trees that died from black cancer.
- Digging the soil, applying fertilizers, and timely watering promote the growth of trees and increase their resistance to disease.
- It is very important to protect trees from mechanical damage, as well as treat wounds by stripping diseased bark and wood to healthy tissue, followed by disinfecting the wounds with a solution of copper sulfate and sealing them with garden varnish.