You might say a beer-mergency is brewing in Michigan. There’s a new pathogen that infects hop leaves and cones. Growers estimate they could lose up to 50% of their yield to the fungus, which causes what’s known as halo blight.
Michigan likes its craft beers. There are 400 craft breweries here, the sixth largest number in the nation, or 5.4 breweries per drinking-age capita, according to 2019 stats from the Brewers Association. Michigan is 10th in the United States when it comes to annual craft beer production, at more than 900,000 barrels.
Thankfully, the state also is home to Spartans from Michigan State University, where researchers are working on strategies to manage halo blight, the disease caused by the fungus. Their estimate of 20-50% yield loss was published in the journal Plant Disease.
MSU says Michigan is the nation’s fourth largest producer of hops, the aromatic flowers used in brewing. Many of the state’s craft brewers prefer to use locally-grown hops for their pilsners, ales and stouts. The new fungus threatens the supply of those locally grown hops; most of the U.S. beer crop is grown in the Pacific Northwest.
Ph.D. student Doug Higgins says on MSU’s website that Michigan craft beer brewers and enthusiasts don’t need to worry about the fungus: “We’re working on it.”
“I think if a grower was growing hops in the eastern U.S., folks should be on the lookout for this disease,” Miles says. “In the meantime, growers should keep up management programs, and follow good disease management from a cultural perspective, increase canopy airflow and keep weed issues down on yards.”
MSU’s work began in 2018, when hop growers noticed some of their plants were looking ill, dotted with brown splotches on their leaves. Researchers ended up extracting DNA from the fungus, confirming it as a new species: Diaporthe sp. 1-MI.
The case was cracked with assistance from MSU plant pathologist Jan Byrne at MSU Plant and Pest Diagnostics and Mary Hausbeck, an MSU Extension specialist and University Distinguished Professor in the Department of Plant, Soil and Microbial Sciences.
The fungus has since been found to be thriving statewide.
“The researchers also suspect that hop blight is showing up throughout the Great Lakes region and other locations with wetter, more humid climates than the growing regions out West,” according to the MSU Today.
Miles explained how growers have estimated losing between 20% to 50% of their yield to the fungus.
“This was determined by following historic yields in specific blocks that experienced halo blight year over year,” he says. “The loss occurs due to cone shatter which causes cones to be lost during the automated process of harvest. In general, most yards in 2020 didn’t have a significant amount of halo blight, but yards that did have it in 2020 had a rough year.”
What does all of this mean for the future of Michigan craft beer?
The Michigan State University team is investigating an array of questions, including how the fungus is spread, where it comes from and how it can be controlled.
Fungicides are already approved for use in hopyards; researchers say they hope to have information over the next few years on how well those measures work against the new intruder.
This news comes at time when craft beer production has been growing in Michigan, bucking a national trend, according to MLive. Small, independent brewers make most of the craft beer in the state, and production was up 4% from 2017 to 2019, compared to 10% drop over the past decade nationwide.
Miles says Michigan craft brewers may need to source hops from the Pacific Northwest if the estimated yield losses come to pass. Unfortunately, that beer may not be quite the same.
“Michigan hops do have a specific terroir, a term commonly used on wine grapes …” Miles says. “Hops are unique because they are grown in humid climate and that causes a different flavor profile of aromas in the cones.”