What diseases seedlings suffer from: 10 most common problems

Seedling diseases can be infectious and non-infectious. The former are caused by pathogenic agents, develop quickly and are easily transmitted from plant to plant. Depending on the type of pathogen, diseases can be fungal, viral or bacterial. Non-infectious diseases are most often caused by violations of agricultural practices. Problems can arise at any stage of seedling cultivation – both immediately after emergence and after transplanting seedlings to the garden bed.

What diseases most often affect seedlings and how to combat them – we will analyze in this review.

Brown (olive) spot

The scientific name of this disease is cladosporiosis, and it is caused by parasitic fungi of the same species Cladosporium, which can affect vegetable (tomatoes, cucumbers, melons, squash) and ornamental crops.

The first symptom is single small yellowish-gray or light green spots, sometimes with a yellow border, which darken over time. On the back of the leaf, these spots are covered with a light-gray coating, similar to a web, and as the disease progresses, holes appear in their place. Then the affected leaves curl, dry out and fall off.

Fungal spores can overwinter on infected surfaces and tools, are easily carried by air, and can also get into the soil with irrigation water. Preventing the development of the disease and curing seedlings at an early stage can be done by treating seeds and young plants with a biofungicide solution: Alirin-B, Gamair, Sporobacterin, Trichoplant, Fitosporin-M. In case of severe damage, you will have to resort to more powerful fungicides: Abiga-Peak, Bravo, Consento.

Verticillary wilting

Verticillium wilt is a fungal disease, and its main symptom is loss of turgor, which usually begins with the top or individual leaves of the plant. It may seem that the seedlings are wilting from the heat, but after the night, the turgor is not restored. In addition, yellowish-brown spots and interveinal necrosis may appear on the leaves. With insufficient watering, such leaves dry out and fall off over time. The infection progresses slowly and can become chronic.

The fungus gets into the soil from infected plant debris and can live there for a long time. It penetrates plant tissue through minor damage to roots and root hairs. The disease develops most quickly at high temperatures (above 24°C) and frequent changes in soil moisture.

Verticillium wilt control involves proper pre-sowing seed treatment, soil disinfection and proper care. If you still can’t save the seedlings, then fungicide treatment (Previkur Energy, Maxim Dachnik) will help to cope with the disease.

Damping off seedlings

If most of the seeds did not sprout, and the sprouts that appeared died, barely hatching, it means that the conditions for them were unsuitable, and as a result, excessive humidity, lack of oxygen and too high a temperature led to the sprouts rotting. This often happens if you did not remove the film or lid from the mini-greenhouse in time.

This problem is entirely the responsibility of the gardener. To prevent such an outcome, it is important to monitor the humidity inside the greenhouse, regularly ventilate the plantings and remove condensation from the shelter, as well as remove it in time.

Root rot

Root rot, or rhizoctonia rot, affects the root system of plants, penetrating it from the soil. It develops at high temperatures and humidity coupled with a lack of light. First, a rusty coating appears on the roots, then they rot, and signs of the disease become visible on the above-ground part: the stem under the cotyledon leaves darkens, softens and thins, the leaves acquire a bluish-green color, and wet spots appear on them.

Seedlings with a significant degree of damage die – they need to be removed, and the remaining plants can be saved by transplanting into separate containers. Before use, the soil must be disinfected and populated with beneficial bacteria by pouring one of the biological preparations: Alirin-B, Baktofit, Gamair, Fitosporin-M.

Root rot

This disease is known to most gardeners under the “pseudonym” black leg and is most often provoked by fungi, although sometimes it has a bacterial nature. Both pathogens act in the upper soil layer, causing rotting of the root collar of plants. Seedlings are most susceptible to the disease from the moment of germination until the appearance of 2-3 true leaves. Improper care accelerates the development of the disease: excessive watering, dense planting, temperature changes.

When a characteristic sign appears on the seedlings – darkening and the appearance of a “constriction” at the base of the stem – in most cases this means that the root collar has already rotted, the nutrition is disrupted and it will not be possible to save the plants. Damaged specimens should be removed to give a chance to the remaining healthy ones. After this, treat the seedlings and soil in containers with a fungicide solution (Alirin-B, Gamair, Sporobacterin, Fitosporin-M).

Mučnistaâ rosa

The first sign of this fungal disease is the appearance of white “mealy” spots on the upper side of the leaves. This coating is easily removed with a finger and looks quite harmless, but if you do not treat the plants in time, you can quickly lose all the seedlings. Mycelium spots first appear on the lower leaves, gradually spreading upward, then grow and “capture” the entire surface of the leaves and stems.

Volatile spores of the fungus live in the soil, on dirty tools and containers, and are easily carried by wind, water and insects. They begin to actively reproduce at high (25-30°C) air temperatures and frequent changes in humidity.

Powdery mildew is “omnivorous” – it can affect any vegetable, green and ornamental crops, and therefore it is important to stop the symptoms at the first appearance. In indoor conditions, biofungicides (Alirin-B, Gamair, Fitosporin-M) are used for this, and if the fungus has settled on seedlings planted in a greenhouse, you can use an effective triple-action drug Triovit Jet based on sulfur, which acts simultaneously as a fungicide, acaricide and microfertilizer.

Downy Mildew

Downy mildew on seedlings can be identified by yellowish-red spots that are covered with a light or gray coating on the back of the leaves. This is what distinguishes downy mildew from real mildew, which forms a coating on the “front” side of the leaves. The difference is also in the pathogen of the genus Pseudoperonospora that causes the disease – this is a pseudo-fungus that “behaves” like a real one. It develops most actively in cool and humid conditions.

This pathogen can attack almost all plants: from beets and sunflowers to flower crops. Among vegetables grown through seedlings, pumpkins (especially cucumbers) and cruciferous plants most often suffer from downy mildew.

Prevention of downy mildew consists of proper pre-sowing seed treatment and soil disinfection, as well as compliance with agricultural practices (watering, ventilation, lighting and fertilizing). Preventive spraying with hay bacillus and trichoderma preparations works well. Diseased plants can be treated with a solution of Sporobacterin or Previcur Energy, after removing damaged leaves.

Fitoftoroz

Usually, late blight lies in wait for garden crops in the second half of summer, when cool rainy weather sets in. However, under “fortunate” circumstances, plants can catch this disease even at the seedling stage, this is especially true for eggplants and peppers.

The disease can be identified by shapeless grayish-brown spots with a light green border and a white coating on the underside of the leaf. The spots first appear on the leaves, but quickly spread to the petioles and stems, and in adult plants, to the fruits.

If you miss the onset of the disease, it will be difficult to save the seedlings. Therefore, it is recommended, firstly, to carry out prevention (seed disinfection, crop rotation, sparse planting, selection of resistant varieties). And secondly, at the first symptoms, you need to remove the infected parts as soon as possible and spray the plants with a biofungicide solution: Alirin-B, Albit, Baktofit, Fitosporin-M. In case of significant damage, copper preparations (Bordeaux mixture, Cuprolux, HOM) will help, which must be dosed strictly according to the instructions.

Fusarium wilt

This type of wilting is named “in honor” of the fungus Fusarium, which causes it. The pathogen can live in the soil or in seeds. Seedlings can also be infected during picking, which often damages the thin roots. The disease spreads and develops rapidly, especially in the presence of aggravating factors – for example, high humidity.

Fusarium on seedlings is manifested by paleness, yellowing and drying of leaves (from bottom to top), the appearance of reddish spots on them and a dirty pink coating on the lower part of the stem. Severely affected plants cannot be cured – they must be removed along with the root ball, and the remaining ones must be sprayed with a solution of Sporobacterin, Fitosporin-M, Trichocin or other preparations based on hay bacillus or trichoderma.

Black spot

At the beginning of the disease, small round spots with a diameter of 1-2 mm appear along the edges of the leaves; their color can be black or brownish-green with a black border. Similar marks, but more elongated, can also be seen on the petioles of leaves and stems. Over time, the number of spots increases and they cover the entire above-ground part of the plants with a small black rash. This leads to the death of the leaf mass, and in the case of young seedlings – to its death.

The fungus most often lives on seeds that were not properly disinfected before being planted in the soil. Its active spread is facilitated by high (25-30°C) temperatures and increased humidity.

Infection can be prevented by spraying seedlings with Baktofit, Fitolavin, Fitosporin-M. If prevention does not help, the diseased plants will have to be removed, and the remaining seedlings will have to be treated with copper preparations (Bordeaux mixture, HOM).

In order not to treat seedlings already at the first stage of development, take all possible preventive measures in advance: choose disease-resistant vegetable varieties, thoroughly disinfect the soil and treat the seeds before sowing. After germination, carefully observe the seedlings and respond to symptoms in a timely manner. Only in this case will you not lose the seedlings and will have a harvest!