Pleospora tarda

Systematic position and type of pathogen. Pleospora tarda belongs to the kingdom Fungi, phylum Ascomycota, class Dothideomycetes, and genus Pleospora. It is a microscopic ascomycete fungus acting as a plant pathogen capable of infecting a wide range of plant tissues, exhibiting both saprotrophic and parasitic characteristics depending on the host plant's physiological status.

Diseases and host crops. This pathogen is responsible for leaf spots, stem rots, and necrosis. In agronomy, this species is frequently associated with diseases affecting cereal crops, legumes, and various ornamental plants. The fungus enters plant tissues through stomata or mechanical injuries, triggering the gradual death of epidermal and parenchymal cells.

Biology and life cycle. The life cycle of Pleospora tarda involves both a sexual stage (production of perithecia or pseudothecia) and an asexual stage (anamorphs). The fungus overwinters as mycelium or fruiting bodies on crop residues left in the soil. In spring, under favorable conditions, ascospores are released into the air and dispersed by wind or rain splashes onto healthy host plants.

Conditions for development and harmfulness. Optimal conditions for infection include moderate temperatures (18–25°C) and high humidity, particularly during prolonged rainfall. The economic damage manifests through decreased photosynthetic activity in leaves, premature desiccation of stems, and, consequently, significant reductions in grain yield or loss of marketability of the produce.

Protection and control measures. Management strategies rely on crop rotation designed to avoid host susceptibility. Key practices include:

• Deep plowing to bury crop residues;
• Cultivation of resistant or tolerant varieties;
• Prophylactic application of fungicides, specifically triazoles and strobilurins, during critical growth stages.