Peziza vesiculosa

Peziza vesiculosa, commonly known as the common dung cup, is an ascomycete fungus often found in greenhouse environments. While typically considered a saprotrophic organism, in intensive agriculture it acts as a nuisance pathogen, colonizing soil surfaces and potting mixes, thereby interfering with the normal development of various horticultural crops.

This fungus predominantly affects young seedlings and delicate ornamental plants grown in organic-rich media, such as composted manure or dense peat-based soils. It thrives in humid conditions characteristic of greenhouse production, where moisture levels remain consistently high and drainage is often insufficient.

The primary symptom of infestation is the emergence of distinctive cup-shaped or bladder-like fruiting bodies (apothecia) on the substrate surface. These clusters, ranging in color from tan to brown, grow rapidly and physically obstruct the soil surface. This growth can hinder gas exchange and potentially crowd out young plant stems, leading to stunted development.

Development and spread are driven by excessive soil moisture and the presence of abundant undecomposed organic material. The fungus reproduces through airborne spores, which disperse easily in enclosed, poorly ventilated spaces. Once established, the fungus can rapidly colonize greenhouse benches and seedling trays if environmental conditions remain stagnant.

Effective management focuses on cultural controls and sanitation. It is essential to sterilize potting mixes prior to use and ensure the greenhouse environment has adequate airflow and drainage. Strategies include:

• Regular cultivation of the soil surface to promote drying.
• Removing fruiting bodies manually to reduce spore load.
• Monitoring irrigation to avoid waterlogged conditions.