Phoma eupyrena

Phoma eupyrena is a fungal pathogen belonging to the kingdom Fungi, phylum Ascomycota, and the genus Phoma. It is recognized as a polyphagous parasite.

The fungus develops a septate mycelium which can be hyaline or olive-tinted, creating small globular fruiting bodies known as pycnidia.

Conidia produced within these pycnidia are typically unicellular and hyaline, serving as the primary units for dispersion in moist environments.

This species is well-known for its ability to form chlamydospores, which allow it to persist in the soil for several years despite adverse weather conditions.

Being both a facultative parasite and a saprotroph, it easily survives on decaying plant organic matter, making it a persistent challenge in crop fields.

Phoma eupyrena affects a wide range of agricultural crops, including potatoes, cereals, sugar beets, and various field-grown vegetables.

The damage is primarily characterized by the rot of root systems, stems, and tubers, which significantly reduces total harvest quality and yield potential.

In potato storage, the fungus induces dry rot, a condition that can destroy stored supplies if temperature and humidity levels are not properly managed.

Cereal crops often suffer from root and crown rot, which weakens the stalks, limits nutrient uptake, and ultimately leads to lodging or stunted growth.

Seedlings are highly susceptible and may experience pre-emergence or post-emergence damping-off, leading to sparse plant stands and required reseeding.

The development of the disease is favored by moderate temperatures and high soil moisture, typical conditions during the spring and autumn seasons.

Conidia are dispersed through splashing rain, irrigation water, and wind, as well as mechanical transport by insects feeding on infected tissues.

Storage rot is particularly problematic when temperatures range from 5 to 20 degrees Celsius combined with high humidity in the storage facility.

Infection cycles are initiated by spores surviving in the soil or on seeds from the previous season, allowing the pathogen to reappear early.

Multiple generations of the fungus can occur within a single growing season, provided there is a continuous supply of host material and moisture.

Early symptoms include the appearance of brown or dark necrotic spots on the stems, roots, or tubers of the affected plants.

Infected potato tubers show sunken, dark spots with dry, shriveled tissue beneath the surface, often featuring internal cavities or hollow spaces.

The presence of tiny, black, dot-like pycnidia scattered across the surface of the lesions is a key diagnostic feature for confirming the infection.

Plants often exhibit wilting during the hottest part of the day, indicating that the vascular and root tissues have been severely compromised.

Internal browning of the stem base and vascular bundles is frequently observed, reflecting the systemic invasion of the fungus into the plant structure.

Crop rotation is the most effective cultural practice to manage Phoma eupyrena, effectively breaking the disease cycle by removing susceptible hosts.

Deep plowing and proper sanitation of crop residues are essential to reduce the primary inoculum load present in the topsoil layers.

Seed treatment using systemic fungicides is highly recommended to protect germinating seedlings from early-season infections and soil-borne pathogens.

• Selection of resistant or tolerant cultivars where available.
• Careful handling during harvest to prevent mechanical wounds.
• Strict temperature control and ventilation in storage rooms.
• Regular field scouting for early detection of symptoms.

Foliar application of fungicides may be necessary during the growing season if weather conditions become conducive to rapid fungal spread.