Genus species: Botryosphaeria ribis
Distribution:The disease has been identified in NY and CT, but is likely present in other New England states.
Crops of Concern: Currants.
Potential for Economic Impact:The pathogen is protected within the canes of the currants and can result in plant death and planting decline in as little as two years without proactive management and inoculum reduction. It seems to affect all species of Ribes, but red currant varieties are more severely impacted than black currants.
Identification: Young shoots infected by B. ribis will become chlorotic and turn from green to pale brown. Developing fruit strings will become shriveled and fail to color. As the infected canes mature over time, the vascular tissues in the center will decay and become hollow. Once the cane is dead and no longer transporting nutrients, the fungus will make small (2mm in dia.) round black survival structures, stromata, which burst through the empidermis near tips of infected shoots. These later develop internal structures to release infective spores the following season. These spores are release at bud break and infect the newly open buds. Completely dead canes are hollow and can break off during mechanical harvest, heavy snows, and strong winds.
Monitoring and Management:Watch for a rapid blight of young shoots during early fruit development, and scout mature canes for the small black survival structures prior to budbreak.
- Cultural Management – Remove and burn infected canes before budbreak and at the end of the season.
- Chemical Management – See listings under specific crops in the Cornell Pest Management Guidelines for Berry Crops.
Resources:
- The Reemergence and Management of Currant Cane Dieback in the Northeastern United States– Plant Disease 94: 1283-1289