Understanding Blackberry Collapse
Identifying a previously unknown cause of cane decline and building tools to help understand its spread
In 2020, Oregon blackberry growers began reporting patches of ‘Columbia Star’ plants dying in commercial fields.
The condition became known as Blackberry Collapse, but its cause was unknown.
A research project completed from 2021–2025 investigated fungal pathogens associated with the problem and identified Gnomoniopsis idaeicola in lesions near the crown of affected blackberry plants. Laboratory testing found that G. idaeicola and Kalmusia coniothyrium, a common cane-blight pathogen, produced the largest lesions among the pathogens evaluated.
Because Blackberry Collapse could not be reliably identified from visible symptoms alone, researchers developed a multiplex PCR diagnostic assay to detect and identify G. idaeicola in blackberry tissue. Testing also detected the pathogen in tissue beyond the visible lesion, helping researchers better understand how infection could move within affected plants.
Regional survey work added another part of the picture. In 2024, G. idaeicola was isolated from seven of eight fields surveyed, although it was recovered from only 6% of the 195 cane samples processed. The research also examined fungicide sensitivity and longer-term approaches to understanding disease management.
Together, the work moved Blackberry Collapse from an unexplained problem being observed in commercial fields toward a disease that researchers could identify, test for and continue investigating.