Roesleria root rot

The disease is caused by the ascomycete fungus Roesleria subterranea (often referred to as Roesleria hypogaea). This soil-borne pathogen primarily targets the root systems of perennial plants. By colonizing the roots, the fungus disrupts nutrient and water uptake, which gradually leads to the decline of the host plant's overall health and physiological stability.

The primary hosts of this pathogen include grapevines and various species of stone fruit trees. While it is most frequently reported in vineyards, it can also infect other woody plants in nurseries. The disease typically presents as localized outbreaks, which can slowly spread across a plot if environmental conditions remain favorable for the fungal mycelium.

The diagnosis is often complicated by the underground nature of the pathogen. Small, greyish, club-shaped fruiting bodies of the fungus may appear on the roots of the affected plant. Above-ground symptoms are non-specific: they include stunted growth, chlorosis, yellowing of the leaves, and premature wilting, often leading to total plant failure during periods of high environmental stress.

Environmental factors play a critical role in the development of Roesleria subterranea. High soil moisture, poor drainage, and limited soil aeration create the perfect conditions for the fungus to flourish. The pathogen spreads through contaminated soil, infested nursery stock, and can be easily transferred between plants via contaminated garden tools or runoff water during heavy irrigation or rainfall.

• Ensure only certified, disease-free nursery stock is used for planting.
• Improve soil drainage to prevent stagnant water around the root zone.
• Remove and destroy infected plants, including all major root residues.
• Disinfect soil or implement fallow periods in heavily infested areas.

The economic impact of Roesleria root rot is significant, as it leads to the loss of established perennial crops. The fungus is persistent and can survive in the soil for extended periods on decaying root fragments. Because eradication is challenging, the most effective management strategy focuses on strict prophylactic measures and maintaining optimal soil conditions to prevent the establishment of the pathogen.