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Powdery mildew is a disease from which the vast majority of horticultural crops are not immune. Tomatoes also suffer from it. The disease is quite easily recognized by the symptoms; in the early stages of development, it can be successfully fought with folk remedies. In severe cases, powdery mildew on tomatoes can be treated with biologics and chemicals with fungicidal properties. But, of course, it is better to prevent infection – agricultural practices and preventive measures will help in this.
What is this disease
Powdery mildew on tomatoes is a disease also known as white or ash. It is caused by a group of marsupial fungi. It develops quite quickly, the incubation period between the ingress of spores on the plant and the appearance of characteristic symptoms is about a week.
Tomatoes are not immune from infection with powdery mildew either in open ground, or in a greenhouse, or at home.
Causes of appearance
The spores of the fungus that causes powdery mildew are very easily moved over long distances with the help of gusts of wind. They are also carried by insects. Often, the gardener himself contributes to the infection. It “transfers” pathogens from diseased bushes to healthy ones when watering, as well as in the process of gardening, neglecting the disinfection of gloves, tools, and equipment.
The “risk factors” that increase the likelihood of powdery mildew infestation of tomatoes include:
- rainy weather that has been established for a long time, combined with large differences in day and night temperatures;
- excessive density of landings;
- neglect of weeding;
- excess nitrogen in the soil;
- irrigation errors.
With this method of watering, fungal spores are very easily transferred from diseased bushes to healthy ones.
Signs of infection
The earliest symptom of powdery mildew on tomatoes is small pale green or yellowish round spots on the underside of the lower leaves. Gradually, they “blur”, increasing in size, their surface is covered with a layer of grayish or whitish powdery or “hairy” coating, resembling spilled flour. Drops of a cloudy liquid – exudate ooze from infected tissues. Then the plaque becomes denser and darker, changing the shade to gray-violet.
Tissues under a layer of plaque subsequently die off – dry out or rot
If nothing is done, powdery mildew gradually “rises” higher on the leaves, passes to their front side. At the same time, it “spreads” on the stems and fruits of tomatoes. Shoots lose their tone and droop, stop growing. Buds and ovaries wither, dry and fall off. In ripening tomatoes, the skin is covered with “wrinkles” and dark “weeping” spots, they crack and rot.
At an early stage of development, powdery mildew on tomatoes looks relatively harmless.
What is dangerous disease
If within 3-4 days after the discovery of the first symptoms indicating powdery mildew damage to tomatoes, they are not provided with competent treatment, the process of tissue necrosis begins. This means “failures” in all vital processes for the plant, including photosynthesis and metabolism. As a result, the bushes practically stop in development, flowering and the formation of ovaries stop. Already existing buds and tomatoes dry up and fall off.
Tomato fruits with signs of powdery mildew are inedible; Pets and livestock should not be given either.
Control measures for powdery mildew on tomatoes
If the defeat of tomatoes with powdery mildew is noticed in the initial stage, the bushes can be saved with the help of folk remedies. They are also used for preventive treatments. When time is lost, “heavy artillery” is used in the form of fungicides of chemical and biological origin.
Agrotechnical methods
Often, the gardener himself is to blame for the infection of tomatoes with powdery mildew, making mistakes in care or simply “abandoning” plantings. The following agrotechnical methods will help protect them from the disease:
- dressing seeds in a solution of a fungicide or a folk remedy with antifungal properties;
- weeding tomatoes as needed;
- pest control, which are carriers of powdery mildew spores;
- loosening the soil in the garden;
- gradual “denudation” of the stem by removing the lower leaves;
- proper watering;
- application of nitrogen fertilizers only at the beginning of the growing season, when tomatoes are actively growing green mass;
Only seeds already treated with fungicide by the manufacturer do not need dressing
Folk remedies
Folk remedies against powdery mildew are completely safe for plants and future crops. They can be applied at any time. The main disadvantage is the short-term effect.
Solutions with antifungal properties (per 10 liters of water):
- food or soda ash (2 tablespoons);
- whey or kefir (1 l) and iodine (12-15 drops);
- potassium permanganate (1,5-2 g, until a bright pink shade).
Also prepare infusions:
- wood ash (0,5 l jar) is poured with boiling water (3 l), left for 5-6 days in a dark, warm place;
- garlic or onions (chopped heads or “arrows”) are poured with warm water in a ratio of about 1: 2, insist 3-4 days.
To protect against powdery mildew, tomatoes should be sprayed every 10-15 days.
Chemicals
Agrochemicals are the most potent treatment for powdery mildew on tomatoes. They are used in strict accordance with the instructions, otherwise, you can harm the plants themselves, the environment and your own health by eating tomatoes from improperly processed bushes.
Since each fungicide has its own “waiting period”, it is recommended to apply them before flowering. Then it is better to manage with biological products and folk remedies.
To combat powdery mildew on tomatoes, use:
- Quadris;
- Topaz;
- Baileton;
- Acrobat MC;
- Horus;
- Speed;
- Privent;
- Ridomil-Gold;
- Abiga Peak.
To work with agrochemicals, wear clothes and shoes that minimize the risk of contact with the solution on the skin
Biopreparations
The effectiveness of biological products against powdery mildew on tomatoes is due to the presence in the composition of strains of bacteria or fungi, for which the pathogen is food or a “natural enemy”. They do not begin to act immediately, but they “work” softer than chemicals and have a minimum “waiting period”.
Tomatoes with signs of powdery mildew damage can be treated:
- Phytosporin;
- Fitolavin;
- Phytocide;
- by Gamair;
- Maxim;
- Alirin-B;
- Planrhizoma;
- Baktofit.
In severe cases, biological products only slow down the development of the fungus, but the plants do not completely “cure”
How to get rid of powdery mildew on tomatoes in a greenhouse
High humidity and “stuffiness” of the air are factors favorable for the development of powdery mildew fungus. Therefore, tomatoes in greenhouses suffer from this disease more often than in “street” beds. To protect them from powdery mildew, the greenhouse must be regularly ventilated.
Since in most cases the bushes “pick up” the fungus from the ground, the lower leaves of the tomatoes are gradually removed over the course of time. For fruit ripening, a stem leafy in the upper third is quite enough. The bottom two thirds are left bare.
Also in the greenhouse, “preventive” treatments with fungicides are practiced at intervals of 15-20 days. Before flowering, it is quite possible to use agrochemicals, after which they switch to biological products.
Tomatoes do not like cold drafts very much: they negatively affect the plant’s immunity, “facilitating the work” of the pathogen
Prevention of powdery mildew on tomatoes
The following simple preventive measures will help to significantly reduce the risk of infection of tomatoes with powdery mildew:
- Compliance with the rules of crop rotation. In the same place, tomatoes can be planted at intervals of 3-4 seasons. Other Solanaceae at this time are also not recommended to be placed in the garden. If you neglect the rules of crop rotation, pathogens that are dangerous to the crop accumulate in the soil, including a fungus that causes powdery mildew.
- Landing planning on site. The “neighborhood” of tomatoes with other Solanaceae is a bad idea. If one of the crops “picks up” powdery mildew, there is a high probability that others will quickly become infected.
- Compliance with the landing plan. For each variety or hybrid of tomatoes, the seed producer determines it, depending on the size of the bush. With the “crowding” of plantings, favorable conditions are created for the activation of the powdery mildew fungus and other pathogens.
- Regular site inspections. If you make a “bypass” every 5-7 days, you can notice powdery mildew on tomatoes at an early stage, when it is easier to deal with.
- Quality care. Competent agricultural technology has a positive effect on the overall endurance, “stress resistance” and immunity of tomatoes. They are more successful in resisting any pathogens, including powdery mildew.
- Disinfection of tools, inventory, gloves every time after work. This applies not only to care for adult plants, but also for tomato seedlings. By the way, before sowing seeds, the substrate and soil also need to be disinfected.
- Autumn cleaning. At the end of the season, all plant debris is removed from the tomato garden and burned. The soil is dug up or at least deeply loosened. This deprives the spores of the powdery mildew fungus of the chances of a successful wintering.
In the greenhouse in autumn, it is advisable to partially replace the soil or disinfect it, treat all surfaces with an antiseptic
Sustainable varieties
Resistance to powdery mildew, as a rule, “comes in a set” with the general endurance of a variety or hybrid of tomatoes, the presence of good immunity in general. These properties are:
- Marmande;
- Roma;
- Scarlet candles;
- Battanya;
- hospitable;
- Pink honey;
- Giant;
- Charisma F1;
- Vologda;
- Ural F1;
- Firebird F1;
- Bohemia F1;
- Flash;
- Koenigsberg;
- Chio-chio-san;
- Yablonka of Our Country;
- Pot-bellied house;
- Waterfall;
- Geisha;
- Ilyich F1;
- Crimson Giant.
Conclusion
Powdery mildew on tomatoes is a disease leading to quite serious crop losses. If characteristic symptoms are detected in time, it is quite possible to minimize damage to plants by using folk remedies. When the process of disease development has already gone far, you will have to use biological products, agrochemicals and, possibly, get rid of badly affected bushes.
