Conidiobolus

Conidiobolus is a genus of fungi primarily known as entomopathogens but recognized in agronomy for its occasional role in plant root and stem degradation. These fungi belong to the order Entomophthorales and can thrive in moist, nutrient-rich environments, often colonizing plant tissues under stress.

The causative agent belongs to the Zygomycota phylum. It spreads via air-borne or water-borne conidia. While they are beneficial in controlling insect populations, their presence in large quantities in a greenhouse or field environment can occasionally lead to opportunistic infections of plant roots, especially in waterlogged conditions.

Crops most susceptible to these infections include high-value greenhouse vegetables and ornamental plants grown in peat or substrate-based media. The pathogenicity is generally considered secondary, attacking plants that have already been weakened by other factors or environmental imbalance.

Key symptoms include rapid yellowing of lower leaves, stunted development, and necrosis of the root collar. In severe cases, the infected root system fails to support the plant, leading to wilting that does not recover after irrigation. A white, fuzzy mycelial growth may be visible under high humidity.

Prevention is centered on environmental management. Agronomists recommend monitoring soil moisture levels closely, improving drainage, and ensuring proper airflow in confined spaces. Integrating beneficial soil microbes like Trichoderma species helps create competitive exclusion, preventing Conidiobolus from establishing itself in the crop root zone.