Lupine anthracnose - how to treat and how to prevent?

In recent years, lupine anthracnose (also known as burn spot) affects all varieties of this plant everywhere, significantly reducing the yield. In some years, crops disappear completely. Most susceptible to the disease are Mediterranean lupins (white and yellow). Anthracnose belongs to a group of fungal diseases and is mainly spread through infected seeds. Infection control includes agricultural practices and the use of chemicals.

Description and ways of spread of the disease

The disease is caused by a pathogenic fungus - Colletotrichum lupine. It is the features of its life cycle and the path of distribution that prevent the complete eradication of anthracnose.

The high severity of the disease is due to the following factors:

• The ability of Colletotrichum lupine to actively sporulate. In a short period of time, under suitable conditions, billions of disputes are formed.
• Possibility of re-formation of conidia on sporozoans.
• The likelihood of a diffuse variant of the development of the disease without symptoms.
• Ability to reserve on other plants, making them a source of infection.
• Related fungi-pathogens affecting alfalfa and strawberries are also capable of causing lupine anthracnose.
• A short incubation period (3–7 days) under conditions optimal for the development of infection.
• The fungus retains the ability to sporulate on plant residues and in the upper soil layer.

Single-celled fungal spores are spread by wind, with raindrops, on pollen, carried by people, animals, equipment over long distances. The fungus penetrates into the plant tissue at the level of the root collar and begins to develop inside. Lupine can also become infected through damaged areas that have been exposed to raindrops containing spores.

Manifestations of anthracnose on lupine

The development of the fungus is most active at a temperature of 23–27 ° C and an air humidity above 80%. Frequent rains contribute to the spread of infection.

The disease begins to manifest itself at the initial stage of seedling development:

• pinkish-brown spots appear on the stems and cotyledonous leaves;
• petioles of newly emerging leaves become curved, may break;
• later, ulcers and brown streaks appear on the stems, the shoots are deformed;
• the surface of the ulcers is covered with a pink bloom, consisting of spores;
• then the ulceration turns brown and darkens;
• necrotic areas with light bordering appear on the edges of young leaves;
• at the final stage of the disease, the growth point of the shoots dies off, the lupine loses its ability to build up its vegetative mass and dies.

There is a rapid infection of neighboring plants around the diseased bush. Such foci are distinguished by a change in color against the general green background of lupine crops. If the disease develops during the fruiting phase, signs of anthracnose appear on the beans. The fruits are deformed, ulcerated, and their seeds become infected.

If, during the appearance of foci of the disease on crops, weather conditions favor the development of the fungus, unstable varieties of lupine can be completely destroyed by the infection. In this case, on resistant varieties, a significant part of the crop is lost. The disease is insidious and, under conditions unfavorable for the fungus, turns into a latent form.

Pathogenic microorganisms penetrate into plants without forming ulcers or other signs of anthracnose.The seed material of such lupine also looks healthy, but the seeds are infected and can cause disease for 3 or more generations of the crop under favorable conditions for the fungus. Moreover, anthracnose can appear at any stage of plant growth.

Disease control measures

The fight against the disease must be comprehensive. Single measures will not lead to the desired result. It is necessary to use a number of agrotechnical methods to prevent the spread of the fungus and to use chemicals for treating crops.

Preventive actions

As a preventive measure, a number of agrotechnical techniques are used that reduce the incidence rate to an insignificant percentage (4-5%).

Farms where lupine are cultivated are recommended:

• sowing far from ravines, forests, groves, where wild reserves of the anthracnose pathogen may be located;
• sow the crop in a wide-row way;
• purchase seeds of resistant varieties;
• produce mixed plantings (with cereals);
• leave only healthy crops for seeds.

Before planting lupine, seed dressing must be carried out. If foci of disease are found in crops, you should not actively move around them, and also start up equipment. Diseased plants must be destroyed immediately.

After work has been done on the infected plantation, it is necessary to change clothes and wash the equipment used. If crops were affected on the site in the previous season, it is impossible to plant lupines in the same place for the next 5 years. This rule also applies to adjacent areas within a radius of 3 kilometers.

Use of chemical fungicides

Due to the fact that the main source of infection is seeds, it is necessary to pay special attention to their dressing. When sowing mixed with barley, triazole fungicides ("Raxil", "Tebu 60", "Bunker") must not be used in the dosages recommended for cereals. These agents delay the emergence of seedlings and plant development.

It is better to use the disinfectants recommended for lupine - TMTD at a dosage of 2.5 kg / t or Fundazol at a dose of 3 kg / t.

According to the researches of specialists, the drug “Vitavax-200ff” has recommended itself the best for etching. The fungicide is available in liquid form and provides effective protection against a whole group of fungal diseases, including anthracnose. The dosage of the drug depends on the type of lupine intended for planting. In parallel, the fungicide increases the percentage of germination and accelerates their appearance.

If the crops show signs of damage, they should be treated with Bavistin OF (0.5–0.75 kg / ha) or Folikur BT (1 l / ha). If conditions are favorable for the development of the disease, the treatment is repeated after 10-12 days.

If you carry out a set of protective measures to combat anthracnose, it will be possible to avoid the loss of grain and green mass. The spread of the disease should not be allowed when foci appear. In case of severe infestation, it is recommended to mow the crops completely and use them as green fertilizer.