ARS | Publication request: Fairy ring disease of cranberry: new developments and characterization of the causal agent

Submitted to: American Phytopathological Society
Publication Type: Abstract Only
Publication Acceptance Date: March 20, 2009
Publication Date: N/A

Technical Abstract: Fairy ring is a disease affecting cultivated cranberries in New Jersey and Massachusetts. The disease causes vine dieback resulting in yield loss and shortens the productive lifespan of cranberry beds, which normally endure over 50 years. The disease spreads across cranberry beds as advancing ‘rings’ that grow for several years. Although the causal agent is reported as Psilocybe agraiella, this is likely incorrect. In late 2008, vines with dark lesions collected from a ring perimeter were found to be covered with ‘infection pads’. This observation was consistent for 22 active fairy rings. Further examination revealed fungal strands growing from the infection pads on the root and stolon tissues. A fungus was isolated and tentatively identified as a Helicobasdium sp., based on DNA sequence analysis. Signs of the pathogen were found on stolons up to 15 cm below the soil surface. This helps explain why control with fungicides is problematic and likely due to limited soil penetration of the active ingredient. Fungicide trials over the past two years have shown increased efficacy in applications with higher water volume. An alternative method of control may be through the use of debilitating (i.e. hypovirulent) fungal viruses. Some species of Helicobasidium are known to contain such viruses. In a preliminary screen of cranberry isolates, we identified a double-stranded RNA virus. If successful, this method of biocontrol could provide effective long-term management.