Contents
With the beginning of the second half of summer, when a lot of dew falls in the morning and the rainy season sets in, nightshades are subjected to a merciless attack by phytophthora, also known as brown rot. This extremely insidious pest attacks plants during fruit ripening and is able to destroy the lion’s share of the crop. Therefore, it is necessary to fight the disease energetically and systematically, correctly choosing the strategy of “war”.
What does it come from
Damage to plants during late blight is caused by oomycetes, which until recently were classified as fungi, and now they have been identified as a separate group of special mycelial organisms. Phytophthora specializes in nightshade representatives, so potatoes, eggplants, tomatoes, peppers and physalis become their victims in the beds.
Oomycetes spend most of their life cycle in the spore phase, located in the soil and the remains of diseased plants. Only with the onset of favorable conditions do they move on to active life, the purpose of which is to leave offspring. When the air is heated to a temperature of +25 – +30 ° C, spores in dew drops can germinate and infect the plant within an hour.
Phytophthora is especially active during sudden changes in daily temperature, when the heat of the day is replaced by rather cool nights, which contributes to frequent fogs and heavy dew. Also contribute to its spread and frequent rains in late July and early August. But dry weather, as well as heat above +30 ° C or cooling down to +10 ° C and below, lead to the almost complete fading of the vital processes of the pest.
Phytophthora affects almost all parts of plants: gray-brown spots appear on leaves, fruits or stems. At the same time, in rainy weather, diseased plants rot, and in dry weather, they dry out and crack. From them, spores are washed off into the ground, and are also actively carried around by drops of water and gusts of wind.
Penetrating quite deep into the soil, phytophthora spores successfully endure winter frosts and in summer they again begin to attack nightshade crops. They can also quite safely overwinter in the remains of infected plants abandoned in the garden.
Is it dangerous for the crop
At the initial stage, gray-brown spots form on the leaves of infected plants. Then the leaves turn brown and die. Phytophthora first affects the leaves near the soil, and then the disease spreads upwards. Juicy, not yet strong young shoots also suffer greatly from pests, on which dark brownish stripes form, which dry out in dry weather and rot in damp weather. The tops and lateral processes of the shoots die off, and the inflorescences located on them turn black and dry out.
However, the most unpleasant thing for a gardener is the appearance of late blight spots on fruits. First, brownish or gray-green spots appear on them, which grow both on the surface and in depth. After this, the stage of hardening begins and decay begins. In the tubers of diseased potatoes, sunken gray spots form on the surface, and inside the reddish color, the affected tissues reach the center. With a strong infection of nightshade crops with this insidious pest, up to 80% of the crop can be lost.
How to treat
Unfortunately, at the moment there are no such effective chemical or biological preparations with which it would be possible to completely disinfect the territory from phytophthora.
The proposed substances can significantly suppress the development of pathogenic microorganisms, but the soil will not be completely freed from them. Also, there is no way to cure a plant after being hit by a disease.
In the fight against the pest, chemical preparations containing copper have proven themselves quite well. The easiest way is to shed the soil for planting nightshade crops with a 1 – 3% solution of copper sulfate, after which the site should be dug up and additionally treated with such a microbiological preparation as Fitosporin-M. You can also use the copper-containing fungicide Ordan.
Among gardeners, it is a fairly common belief that an effective way to deal with this pest is the introduction of chlorine. However, it is unlikely that this substance will be able to destroy the spores, but it will be possible to harm the humus for sure. Neither the soil nor the plants will benefit from this.
Chemicals suppress not only pathogenic microorganisms, but also harm useful fungi in the soil. Unlike them, microbiological preparations act more selectively, since they contain colonies of microorganisms for which pest spores serve as food. The earth is not exposed to harmful influences.
To prevent outbreaks of late blight, it is effective to use such microbiological preparations as Fitosporin-M, Mikosan or Shine. During the summer they should be applied three times. For the soil in those places where it is planned to plant flowers or strawberries, you can use Alirin, which is similar in composition and effect to Fitosporin. If these preparations are not available, then the soil can be treated with Bordeaux liquid.
Prevention
It is very difficult to get rid of late blight that has appeared on the site. However, the implementation of preventive measures allows you to minimize its spread and collect an excellent harvest. Since the main source of infection is the earth, the lion’s share of efforts is directed to it.
Fungicides and microbiological preparations are used to destroy spores in the soil. Since chemicals decompose for a rather long time, after they are introduced, vegetables can only be eaten after a month. Therefore, treatment with copper-containing substances is carried out in early spring. The introduction of microbiological preparations into the soil is allowed at any time, with the exception of the flowering period, when they can harm the nectar-gathering bees.
Phytophthora spores enter plants from the soil through moist air streams ascending from the heated earth. In order to effectively prevent this process, mulching is used. Covering the ground in spring with a layer of mulch a few centimeters thick becomes a reliable barrier against many diseases, the sources of which are spores of pathogenic fungi hibernating in the soil.
It is also important not to plant solanaceous crops densely in the ground. In addition to the fact that the plants in this case lack light and are poorly ventilated, phytophthora will easily move around the beds and infect large areas.
Autumn cleaning and burning of all waste outside the site helps to effectively get rid of spores remaining in the ground parts of plants. After that, the soil should be deeply dug.
A good result is the use of a drip irrigation system for plants. At the same time, the soil is not waterlogged, and the plants receive the optimal amount of moisture for their growth and development. A good way to prevent is the use of crop rotation. Solanaceae should be planted on the same plots of soil at intervals of three to four years.
Another option to avoid damage to plants by late blight is the cultivation of certain varieties of nightshade. These can be either particularly pest-resistant varieties or early-ripening ones, the ripening of which occurs at the time when late blight begins to actively multiply.
Video “Processing ground tomatoes from late blight”
On the record, a woman talks about the method of processing nightshade plants from a disease such as late blight.
