Causes and treatment of cucumber anthracnose: effective control methods

Cucumbers

The appearance of yellow spots on cucumber leaves is a serious cause for concern. One possible cause is anthracnose. This is a serious disease whose symptoms develop rapidly. Without prompt treatment, it can not only reduce yield but also destroy the plant. There are numerous treatments available to combat this disease. Farmers who carefully study their descriptions and apply them according to the instructions see rapid results.

Causes and symptoms

Anthracnose of cucumbers is caused by an ascomycete fungus. The disease develops at temperatures between 4°C and 30°C and humidity levels of approximately 85% to 90%. The period from infection to the appearance of the first symptoms is 5-7 days, although under favorable conditions (at temperatures between 20°C and 25°C), this period can be reduced to 3 days. At temperatures below 4°C and humidity levels below 60%, the disease does not manifest. The infection is transmitted through contaminated plant debris, seeds, and soil. Fungal spores are carried by insect pests, wind, rain, and humans during gardening.

Attention!

Not only cucumbers, but all other vegetable crops are susceptible to the development of anthracnose.

The problem can affect plants at any stage of their growing season. The abnormal process affects all parts of the plant. On seedlings, the disease appears as brown, sunken spots near the root collar. In mature plants, the pathology is easier to recognize:

Leaves. Light green spots approximately 3 mm in diameter appear, which later merge into larger ones—up to 4 cm in diameter. Gradually, the spots take on a copper-brown hue, and the leaves turn brown. In dry weather, they become brittle, and in damp weather, they rot. Holes often appear in the affected areas.
Fruits. Sunken, elongated, ulcer-like spots appear on vegetables. They are light brown in color and can be of any size. The fungal mycelium penetrates the tissue to a depth of up to 4 mm. This causes the cucumbers to darken and gradually rot.
Stem. Weeping, sunken, elongated spots of a brownish-yellow hue appear on the stem. At the site of the spots, the stem gradually thins and breaks. The plant dies. In conditions of high humidity, a pink coating may appear on the affected areas. These are fungal spores. Dark spots called sclerotia then appear.

Therapy

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Anthracnose treatment begins with creating conditions unfavorable for pathogen growth. Both chemicals and folk remedies are used to combat the infection. The advantage of the former lies in their high effectiveness, while the latter is safe for humans and the environment. Experienced farmers combine different products and methods to achieve good results.

Folk recipes

There are many recipes for treating cucumbers. The most common ones used by gardeners are:

10 ml of brilliant green tincture is diluted in a bucket of water and the bushes are sprayed with the prepared solution.
10 drops of iodine are dropped into 1 liter of milk or whey and the resulting medicine is used to spray both plants and soil.
One liter of wood ash is diluted in a bucket of water and sprayed on the above-ground parts of the plant. This slows the growth of the spots. To improve their adhesion, experienced farmers add soap shavings.
Mix 5 liters of whey with 5 liters of water and add 10 g of copper sulfate. Spray the tops with the liquid.
10 g of raw yeast is dissolved in a bucket of water and the prepared solution is poured onto the roots of sick plants.

Attention!

To help plants recover faster, ash is added to the soil.

Use of fungicides

Fungicides are available at all gardening stores. Farmers most frequently purchase:

Fitosporin. Dosages are as follows: 20 g of powder per bucket of water, 8 drops of paste per 400 ml of water, or 50 drops of liquid per 100 ml of water. Spray three times, spaced two weeks apart.
Abiga-peak. First, 50 g is diluted in 1 liter of water, then another 9 liters are added. Bushes are treated three times per season, with 25-day intervals between treatments.
Fundazol. It is used for irrigation, bush spraying, and seed dressing. 1 g of the product is diluted in 1 liter of water. Spraying is performed no more than twice per season. Seeds are treated 30 days before planting.

Disinfection is performed wearing protective clothing, a respirator, goggles, and gloves. After the procedure, discard the gloves, rinse your mouth with water, and wash your face and hands with soap. If the diluted product has not been completely used, discard the remaining material. It should not be stored. After treatment, harvest the plants only after 5-30 days (the time frame depends on the product).

Treatment with Bordeaux mixture

A 1% Bordeaux mixture is prepared as follows: 200 grams of copper sulfate is added to 10 liters of water, and then the resulting solution is combined with lime solution (200-1000 grams of lime per 10 liters). When properly prepared, the mixture has a light blue color. Its shelf life is 24 hours, so it is used immediately after preparation. Some farmers apply this solution to young cucumber seedlings twice in the spring, separated by two weeks. This helps prevent diseases.

Irrigation with copper chlorine oxide suspension

Instead of Bordeaux mixture, some gardeners use copper oxychloride to spray their bushes. This substance is found in many products, including Hom and Abiga-Peak. It combines well with most pesticides, except those containing lime. Application should be carried out with extreme caution to avoid burning the foliage. The product is moderately hazardous to humans and animals. Its decomposition in the soil typically takes no more than six months.

Root watering

If the abnormal process has affected only the root zone of the plant, gardeners prepare a 1% Bordeaux mixture and pour it into the root system of each plant. However, before applying this, be sure to add water to the soil (at least 1 liter per plant). Otherwise, the soil will dry out completely, and the plant will die. Abiga-Pig is used in a similar manner. Repeat this procedure every two days until the disease subsides.

Attention!

To prevent the infection from spreading, bushes, a significant portion of which are affected, are dug up by the roots and burned.

Features of therapy in closed conditions

Greenhouse cucumbers are more susceptible to disease than those grown outdoors. This is due to the following factors:

Greenhouse microclimate (moderately high temperature and high humidity) is more suitable for the development of the pathogen.
The fungus often remains on the inner surfaces of the greenhouse and immediately attacks the seedlings after they are planted.
In the greenhouse, the bushes are planted densely, and this accelerates the spread of infection.

Despite all this, greenhouse plants are easier to treat, as the farmer can regulate the temperature and humidity levels indoors. This is impossible outdoors. At the first signs of disease, the humidity level in the greenhouse is reduced to 60%. This helps slow the progression of the disease. The plants are then sprayed with antifungal agents.

Features of open-ground therapy

Cucumbers grown outdoors are typically infected with fungus through seeds, wind, and insects. Soil and plant debris are often the source of infection. In this case, root irrigation and treatment with 1% Bordeaux mixture have proven the most effective in combating the problem. Irrigate the plants either before 10:00 AM or after 6:00 PM. Applying during the day can cause burns to the foliage. Choose a dry, windless day for spraying. Experienced farmers always check the forecast for the coming days and, if rain is not expected, spray the plants without fear of washing away the medication.

Prevention

Anthracnose is a preventable disease. To prevent it, farmers take the following steps: