Nannizzia fulva

Nannizzia fulva is a species of ascomycete fungus within the Arthrodermataceae family, primarily recognized as a soil inhabitant. While often studied for its dermatophytic nature in animals, it acts as a saprotroph in agricultural soils, potentially evolving into a plant pathogen when environmental stressors weaken the host plants' natural defense mechanisms.

The disease caused by this fungus is classified as a tissue-degrading mycosis. The pathogen invades the plant's basal tissues, spreading through the root system or direct contact with the soil. By secreting extracellular enzymes, the fungus breaks down organic structures, causing rapid decay and necrosis in the infected plant tissues.

Commonly affected crops include various greenhouse vegetable species, nursery seedlings, and ornamental plants sensitive to excessive soil moisture. The infection usually initiates in the root zone, making it difficult to detect until systemic symptoms manifest in the foliage and overall plant vigor, leading to stunted growth or plant mortality.

Symptoms of an infection often include a thin, brownish-orange mycelial mat covering the soil surface near the stem. Affected plant parts show water-soaked lesions that eventually turn dark brown or black. As the fungus progresses, the plant loses its structural integrity at the soil line, leading to damping-off symptoms, especially in younger, more vulnerable specimens.

Management and prevention focus on eliminating the conditions that favor fungal proliferation. Key strategies include maintaining optimal soil drainage, implementing crop rotation, and ensuring appropriate spacing to promote air circulation. Furthermore, solarization of contaminated soil and the use of preventative fungicide treatments are recommended in greenhouses to suppress the development of Nannizzia fulva.