Black leg - protection of seedlings from disease

Black leg is the most common disease of seedlings, it most often affects seedlings of such crops as tomatoes, bell peppers, eggplants, cucumbers, various types of cabbage, radishes, lettuce, and from flowering plants - petunias and others grown through seedlings.

What is a black seedling leg?

Black leg - this is what gardeners who grow seedlings for personal plots or for sale usually call root rot of the neck of seedlings. The disease is fungal, with active development it causes seedlings to lay down and die.

You can understand that your seedling has been affected by a black leg if you carefully examine the base of the seedling stem, there you will be able to see a change in the color of the tissue, that is, its blackening, and with the active development of this fungal disease, the rotting of the plant tissue at the location of the root neck.

Usually, the black leg is most actively manifested from the moment when the sprouts of the hatched seeds just appear above the surface of the soil and until the moment when the seedling forms two or three real leaves.

Why is a black leg formed and developed?

There are quite a few reasons for the formation and active development of such a disease as the black leg of seedlings, it can be:

• soil infected with black leg fungus;
• excessively thickened crops, when moisture stagnates for a long time at the base of the seedlings, which, in combination with plus temperature, creates prerequisites for the development of the disease;
• excessive moistening of the soil, when moisture simply does not have time to evaporate and be used by plants;
• lack of fresh air - when the gardener, fearing a draft, does not ventilate the room at all;
• an excessive amount of moisture in the soil, combined with a lot of heat, are ideal conditions for the rapid development of black leg;
• sharp temperature drops - when the gardener, on the contrary, is overly enthusiastic about airing the room, which sometimes leads to temperature fluctuations of five or more degrees.

If one or more similar conditions occur, sometimes only seven days are enough from the beginning of the development of the black leg to the complete blackening of the seedling stems and the death of the seedlings. If you take such seedlings in your hands, you can feel with your fingers how the stems are very softened or, on the contrary, they are characterized by increased fragility.

Fungi belonging to the genera Olpidium (Olpidium), Pythium (Pythium), or Rhizoctonia (Rhizoctonia) cause the development of black leg. All these harmful fungi live in the upper layer of the soil and feed on dead plant tissue. At high humidity, fungi stop feeding on dead tissues and start feeding on living tissues, or they can feed on these and other tissues at the same time. So, it is the root neck of the seedling that is at risk during this period.

Preventive measures against the black leg of seedlings

To begin with, you should always buy high-quality seeds of modern varieties and reliable manufacturers with a date written, not stamped, on the seed package. At the same time, try to give preference to seeds with a proven reputation, that is, reviews of which already exist, and you can compare this or that variety with the description from the manufacturer. And of course, try to buy varieties that are either tolerant or immune to this disease.

If you are not sure about the seed material, then before sowing, we recommend keeping them in a light pink solution of potassium permanganate for a quarter of an hour, then rinse them in running water.
For prevention, it is also recommended to soak the seeds in a solution of the Sporomax™ B preparation, which can be used as a prevention of the appearance of black leg before and after diving the seedlings, and a day after the diving of the seedlings, carefully process the soil around the seedlings. The main thing when processing is to barely moisten the soil with a solution of the drug, you cannot "pour" the seedlings with it.

Always observe the optimal time of sowing seeds. For this or that variety, for this or that culture, the seed sowing time is always indicated on the package.

You should also not be in too much of a hurry to sow the seeds, the room may not be warm enough, there may be snow outside the window and it may be quite cold, and the cold from the window will only slow down the development of the seedlings, make it difficult for excess moisture to evaporate and allow the black leg to actively develop on your seedlings.

Provide plants with sufficient lighting depending on the seedlings of which crop you are growing. When there is a lack of light, the processes of photosynthesis slow down, the evaporation of moisture is reduced, the immunity of plants decreases, as a result, a black leg appears.

When growing seedlings, try not to use banal wooden boxes and plastic dishes, but peat briquettes or peat-humus pots. These fairly modern "devices" will avoid the appearance of a black leg or reduce the risk of its appearance several times. In addition, seedlings do not need to be removed from peat-humus cups, for example - they can be planted directly in the soil of the greenhouse or in open soil, without injuring the root system at all.

It is important to take care of the soil before planting seeds there. For example, the soil in which you do not have any experience

foreignness, can be etched. The most optimal option is a banal dark pink solution of potassium permanganate. It is prepared as follows: it is necessary to dissolve three grams of potassium permanganate in a bucket of soft (that is, melt or rain) water. Treatment with Sporomax™ B + Sporomax™ T biofungicides also helps to disinfect the soil and rid it of black leg.

After the soil is disinfected in one way or another, let it "breathe" for three days, and then you can start sowing.

After sowing, most gardeners cover the general container with seedlings with food-grade or regular polyethylene film or glass. So, it is possible and even necessary to do this: it creates the appearance of a greenhouse, but every day the air in such a greenhouse must be ventilated by lifting the film and spraying the soil with a sprayer if it starts to dry out, in order to prevent the earth lump from drying out.

Protecting seedlings from the desease

If the black leg was noticed late and part of the seedlings is already affected by the disease, the first thing to do is to prevent the spread of the fungus, that is, to remove the diseased seedlings. Ideally, the remaining seedlings should be transplanted into new, clean soil, but if they are very small, then you can treat the places where sick seedlings and seedlings without signs of infection grew with a solution of biofungicide Sporomax™ B. At the same time, the prepared solution should be watered exclusively under the root system healthy plants. If the disease affected the seedlings, when the plants had already managed to form a pair of real leaves, then Sporomax B solution can be used to treat all the plants as a whole, getting on the leaves, stems and soil.

Alternative methods of combating blackleg are preparations based on copper (copper sulfate, copper oxide, Bordeaux liquid, etc.), but we do not recommend them, since it is enough to disturb the concentration even a little and the plants will die and "burn".

In that case, if the damage is severe and you have both a place and soil at your disposal to transplant healthy seedlings there, it is better to pack them in separate cups, using only disinfected soil to fill them. But even after that, it is still advisable to pour Sporomax™ B into the soil. After planting plants in such soil, they usually do not get sick and develop normally.

Before planting seedlings in open ground, it is also necessary to prepare the area. In order to prevent infection of seedlings with black leg from the soil, it is necessary to take the preparations Sporomax™ B (10 g/10 l of water/1 acre) + Sporomax™ T (30 g/10 l of water/1 acre), spray the soil and cultivate it (cultivation , milling, digging). After that, you can plant seedlings.