Anthracnose

The first symptoms of anthracnose appear as small brown or dark-colored spots on leaves, stems, and fruits. Over time, these spots enlarge, taking on a characteristic depressed shape with a dark margin.

In the center of the affected areas, one can often observe small pads — these are the fungus's conidial sporulation, which can turn pinkish or yellowish under high humidity conditions.

On stems, the infection manifests as elongated ulcers that can lead to constrictions and the breaking of vegetative organs. Severe infections result in premature wilting and the death of the entire above-ground part of the plant.

When fruits are infected, they develop sunken spots that rapidly expand, turning the flesh into a rotten mass. In dry weather, the damaged tissues may crack, exposing the inner part of the fruit.

• Darkening and deformation of leaf blades.
• Appearance of deep ulcers on shoots.
• Presence of spore pads on necrotic surfaces.
• Loss of turgor and drying of affected branches.

The causative agent of anthracnose is the imperfect fungus Colletotrichum parallelophorum, belonging to the class of deuteromycetes. The pathogen's mycelium develops within plant tissues, eventually emerging to the surface to form conidial sporulation.

The fungus can survive in plant debris, soil, and on seeds in the form of sclerotia and mycelium. During the growing season, the pathogen spreads via conidia, which are dispersed by rain droplets, wind, or insects.

The primary source of infection is most often contaminated seeds, where the fungus overwinters under unfavorable conditions. During feeding, the parasite releases specific enzymes that break down the host's cell walls.

The pathogen's life cycle is closely linked to environmental humidity, as spore germination is impossible without liquid water. The species' high aggressiveness is due to its ability to quickly adapt to various host plant tissues.

The biology of Colletotrichum is characterized by high sporulation rates, allowing the infection to cover large areas of crops in a short period under favorable conditions.

Anthracnose development is promoted by high air humidity exceeding 80-90%. Ideal conditions for active pathogen reproduction include prolonged rain, fog, and the presence of dew on plants.

The temperature range most favorable for the disease's spread varies from +20 to +28 degrees Celsius. Sharp temperature fluctuations weaken plants, making it easier for the fungus to penetrate.

Poor ventilation, dense planting, and the lack of regular pruning create an ideal microclimate for infection accumulation. Excessive application of nitrogen fertilizers can also trigger disease outbreaks.

Fungal spread is facilitated by mechanical damage to tissues during plant maintenance or insect activity. In greenhouses, the disease spreads rapidly if ventilation protocols are ignored.

The infection background increases when crop rotation is neglected, as the fungus accumulates in the topsoil over years, waiting for suitable weather conditions to attack new crops.

The harmfulness of anthracnose lies in a significant reduction of crop productivity. The disease affects both vegetative and reproductive organs, leading to total yield loss.

When stems are affected, the transport of nutrients is disrupted, causing stunted growth and underdeveloped fruits. The harvest loses its marketability and becomes unsuitable for long-term storage.

In severe cases, the infection leads to the death of the plant during the flowering or fruiting stage. Economic losses in commercial farming can reach 50-70% in the absence of protection measures.

The disease negatively impacts seed quality, as fungal spores penetrate deep into the embryo or survive on the seed coat, infecting future seedlings.

Chronic infestation of plantations leads to gradual plant exhaustion, which reduces their overall resistance to other environmental stressors and pathogens.

The primary control method is strict adherence to crop rotation and the removal of plant debris from the field after the season ends. Eliminating weeds that may serve as infection reservoirs is mandatory.

The use of healthy, treated seeds significantly reduces the risk of initial disease outbreaks. Selecting anthracnose-resistant cultivars and hybrids is the most effective long-term strategy.

Chemical protection includes regular preventative sprays with systemic and contact fungicides. It is crucial to apply treatments before symptoms become widespread.

Agronomic practices, such as proper crown training and thinning of crops, improve ventilation and lower humidity levels, hindering spore dispersion.

When signs of infection are detected, affected plant parts must be promptly removed and burned to prevent further spore spread across the field.