Ascochitosis cucumber: what is it, symptoms and control measures

Cucumber ascochitosis is a fungal infection of a crop. Microorganisms slow down the growth of plants, but do not completely kill them, continuing to parasitize on a weakened bush.

Fighting infection is a troublesome and complex process. Spores are transmitted to the crop by infecting seeds, and then develop along with the plant. How to defeat ascochitosis in your area and prevent infection of new shoots? Let's figure out what symptoms characterize ascochitosis and how to deal with it correctly.

Pathogen development

The reason for the appearance of ascochitosis is the infection of a colony of cucumbers with parasitic fungi.Greenhouse and greenhouse crops suffer more often. First of all, the fungus is dangerous for weak plants with weak immunity. Rot affects the plant during the fruiting period, less often - during the formation of the stem.

The fungus loves a humid and warm climate, so it is especially active in greenhouses and hotbeds. Fungal spores show increased activity in spring, in good light conditions, when, due to the lack of heat, the cucumber culture is weakened and unable to fight them. The following phases of the development of the disease are distinguished:

1. The parasite infects cucumber seeds and then waits for an opportunity to develop as the plant grows. The spores are on the seeds in a state of suspended animation. At the time of planting in the soil, they begin to gradually increase their population along with the plant. The fungus affects the upper tissues of the cucumber, but does not touch the vascular system, so the plant retains the ability to grow, albeit in a weaker form.
2. The fungus passes into its active form during the tying of the leaves on the cucumber. The defeat begins from the lower tier of leaves, first the pathogen colonizes the tissues, and then the vessels. By April-May, the mycelium is formed and begins to infect neighboring leaves of the plant by air with the help of spores. At the same time, the pathogen expands the area of its presence up the stem, affecting already the middle leaves.
3. The fungus penetrates the fruits and leaves of the upper level by the end of the growing season. Faded watery spots appear on the fruits, which then darken and give way to rust. Weakened fruits degrade and begin to gradually dry out and die.

The fungus does not develop in the soil. During storage, it does not pass from one fruit to another. It also does not reproduce in the roots.

Important! To slow down the expansion of the fungus, it is recommended to carry out seed thermotherapy and disinfection with fungicides, which slows down the development of the disease by 15-25 days.

Disease symptoms

If preventive measures fail to stop the expansion of the fungus, the parasite begins to infect the outer tissues of the plant. Infection of cucumber with black stem rot can be identified by the following characteristic features:

1. First, watery gray spots begin to appear on the stem. Then they begin to turn white and capture an increasing area of the stem. Black rot begins to develop on the vulnerable parts of the stem, where pinching, removal of leaves and fruits.
2. When infected during fruit growth, the fungus begins to attack the edges of the leaves. Then the surface of the leaf turns brown, the disease spreads to the fruit.
3. Fruits shrink and visually look withering, remaining firm to the touch. Such a cucumber ceases to develop, and subsequently decomposition processes begin in it.
4. A possible form of infection in which the fruits become covered with ulcers or turn white. The body of the fruit is covered with a rusty coating and mucus appears, under the influence of which the cucumber begins to rot.

In its development, the fungus passes along with the plant through all stages of its vegetation, gradually rising along the stem from the roots to the upper tier of leaves and fruits. Therefore, if you slow down its progress with the help of a set of preventive measures, then you can successfully grow a cucumber crop and even harvest from it a crop that the fungus does not have time to reach.

Important! Removal of the lower leaves must be done after the appearance of ripe pycnidia of the fungus in early summer. This allows you to restrain the development of mycelium.

Methods of prevention and elimination

It is difficult to fight the fungus, as it does not respond to fungicides during the growing season. With ascochitosis of cucumbers, the control measures should be as follows:

• water crops in the evenings with warm water;
• cover the seedlings with a film until a pronounced stem with leaves is formed;
• perform crop rotation so that spores do not infect the cucumber crop every year;
• buy and plant varieties resistant to ascochita;
• apply chemicals to the soil to protect crops from disease;
• remove all affected leaves on the bush.

If the fungus is fixed on the site, it is necessary to treat with the following preparations:

1. Introduce green manure into the soil shortly before planting seedlings. They increase the immunity of plants and allow them to more effectively resist the fungus. For additional soil enrichment, sanitary crops such as rye and oats can also be planted on green manure.Subsequently, such a crop is crushed and plowed with manure into the ground before planting cucumber seedlings.
2. Disinfect the inside of the greenhouse by spraying the formalin solution on the walls and ceiling. Steam the soil additionally, although this only has a weakening effect on the parasite.
3. Treat seeds with active fungicides such as Vincit, Tiram and Saprol. They will weaken the fungus until it disappears completely.
4. In case of damage to leaves and fruits, spray plants with Bordeaux liquid or a mixture of urea with copper sulfate. In the case of fungus on the stems, a powder consisting of copper and chalk is applied to them.

When using the above methods, you can significantly slow down the progress of ascochitosis along the stem, and as a result, completely eradicate the disease.

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