Tulasnellales fungi

The order Tulasnellales comprises a specific group of basidiomycetous fungi known for their significant ecological role in mycorrhizal symbioses. While they are often essential for the germination and growth of specific plant families, particularly Orchidaceae, they can occasionally behave as opportunistic pathogens under stressed environmental conditions, affecting plant health.

The pathogens belong to the class Agaricomycetes. They typically form thin, crust-like or effused basidiocarps on decaying organic matter or soil surfaces. The fungus develops a mycelial network that can penetrate host root tissues. The biology of these fungi involves specialized interactions where the fungal hyphae enter the plant cells, potentially altering the nutrient exchange balance.

These fungi primarily interact with orchid species, but their presence has been documented in various agricultural soils. Their impact on crops is usually linked to the disruption of established root-fungi symbioses. When the host plant is weakened by environmental stressors, the Tulasnellales may transition from a symbiotic to a parasitic or saprotrophic behavior, negatively affecting root health.

Development and spread are favored by high soil moisture, shade, and the presence of high organic matter content. These fungi thrive in cool to moderate temperatures, typically between 15°C and 22°C. The availability of specific moisture levels in the rhizosphere is the primary factor for the mycelial expansion and colonization of new root zones.

The damage caused by these fungi often manifests as reduced vigor, stunted growth, and susceptibility to other soil-borne diseases. Prevention and control strategies focus on maintaining soil health and preventing waterlogging.

• Implementing proper irrigation scheduling.
• Promoting microbial diversity in the soil.
• Avoiding excessive use of broad-spectrum fungicides that could disrupt beneficial mycorrhiza.