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Scorch and shock are two viruses that infect blueberry crops and are major concerns to growers in British Columbia. Scorch causes severe damage and plant death, while Shock shows similar symptoms, but plants typically recover and remain productive. 

There is a standardized ELISA (enzyme-linked immunosorbent assay) test used by blueberry growers in British Columbia to distinguish cases of scorch and shock. However, in recent years growers have raised concerns about plants that were clearly diseased, but tested negative for both the scorch and shock viruses. Researchers from Simon Fraser University, in collaboration with Phyto Diagnostics – a CFIA-certified laboratory that provides growers with testing and analysis to manage crop health – and the BC Blueberry Council, have investigated the cause of these negative results. 

Genome sequencing revealed that the diseases affecting the plants were likely to be scorch and shock virus, but that the coat protein region of these viruses has evolved over time and is highly variable. This resulted in the established diagnostic tools and tests failing to detect the viruses because they were based on outdated viral sequences. In response, the team has developed more accurate qPCR tools that significantly reduce the instances of false negatives. Updated tests for scorch and shock are now in production at Phyto Diagnostics and will offer growers a more reliable diagnostic option. 

With the development of qPCR tools for this project, Phyto Diagnostics is also well positioned to expand its services to include sensitive PCR testing for applications such as nursery stock and export certification, enhancing its competitiveness. 

In addition, the research team discovered four new blueberry viruses that seem to be present in plants across the Lower Mainland. Tests for these viruses are currently in production at Phyto Diagnostics. This information helps to understand the landscape of viruses affecting local blueberry crops and builds a picture of potential future threats to blueberry production. 

Accurate diagnosis is essential for effective crop management, as scorch-infected plants must be removed early to prevent spread, while shock-infected plants can recover and remain productive. With these improved diagnostics, growers can make informed decisions, reduce unnecessary crop loss and enhance overall productivity.