Capitol News

Wine grapes hold significant economic value in Michigan, with the National Association of American Wineries estimating an impact of over $6.3 billion annually. This includes contributions from direct vineyard operations as well as related activities such as wine tourism.

Grapevines in Michigan, however, face challenges due to their susceptibility to various plant viruses, often hosting multiple viruses simultaneously. To address this, researchers at Michigan State University are working to enhance vineyard health and productivity.

“The first step in controlling viruses is knowing which ones we have in Michigan — and now we know," stated Timothy Miles, an associate professor and principal investigator for the Small Fruit and Hop Pathology program in MSU's Department of Plant, Soil and Microbial Sciences.

Collaborating with the University of California, Davis, the study identifies grapevine viruses affecting Michigan’s vineyards, emphasizing the importance of diagnostic testing and the use of virus-free plant material. The team employed real-time reverse transcription polymerase chain reaction (RT-PCR) technology, similar to methods used in COVID-19 detection, to identify grapevine viruses likely present in Michigan.

Vineyards across various regions of Michigan were examined for virus presence. Findings revealed the grapevine rupestris stem pitting-associated virus (GRSPaV) as the most common. “GRSPaV can cause poor spring growth, delayed bud break, stunting, reduced yield and results in a decline of the overall health of the vine,” explained Kerri Neugebauer, laboratory manager in the Small Fruit and Hop Pathology program.

The research outlines challenges Michigan faces with grapevine viruses attributed to diverse Vitis species cultivated in the state, varying vineyard ages, and the sourcing of plant material from different U.S. locations, which may introduce virus-infected plants.

Timothy Miles highlighted that Michigan growers can now test for these viruses via the MSU Plant and Pest Diagnostics laboratory. “Michigan’s unique Great Lakes climate allows us to grow high-quality wine grapes,” said Jenelle Jagmin, director of the Michigan Craft Beverage Council. "But this climate that differentiates our viticultural areas also presents specific challenges. Miles’ research helps tackle some of the unique pressures that Michigan grape growers face regarding disease and pest management.”

The study enhances understanding of grapevine virus distribution in Michigan, aiding growers in making informed decisions to bolster vineyard productivity and sustainability. The research findings were published in the journal Plant Health Progress.