Jun 30, 2025

Soft spray effect: Michigan vineyard’s disease management pesticide test 

A Michigan winegrape grower is trialing softer pesticides that could lead to additional sustainable efforts not only in his state but also in other U.S. wine-growing regions. 

Shady Lane Cellars, based in Suttons Bay, Michigan, is participating in a $11,000 national farming grant testing new, less impactful pesticide treatments. The work, which began last spring, is testing new ways to manage common diseases that affect winegrapes.

Andy Fles, vineyard and facilities manager, received the grant from Sustainable Agriculture Research and Education (SARE). The Shady Lane Cellars estate winery and vineyard is one of only two Michigan wineries that earned and maintained a rigorous Sustainability in Practice (SIP) certification.

Fles is collaborating with Michigan State University and Extension researchers in the project, which is also funded by the USDA’s National Institute for Food and Agriculture. The research has the potential to positively influence the future of farming, said Fles. 

Fles is trialing on larger blocks than the one- to two-acre plots researchers might backpack spray. Shady Lane is experimenting in two-acre blocks of Pinot Noir, Riesling and Vignole, a white hybrid varietal.

Application changes

The grant is designed to give growers practical tools to try out different products, Fles said. He is collecting data on the treatments through MSU partnerships. 

“The ‘soft treatment’ trial would certainly not reduce the number of applications, but if we can have plant-derived pesticides such as a lupine seed extract or a food-grade orange oil do the work for us and show positive disease control outcomes, then we can reduce or eliminate petro chemical-based pesticides without sacrificing quality,” he said.  “And that is what the results show from 2024, so we will look to continue and expand going forward.”    

The varietals are all highly susceptible to botrytis bunch rot and sour rot, two highly problematic cluster rots Shady Lane Cellars encounters late season. They are comparing conventional management spray programs with a reduced-risk  program that uses as little crop protectants as possible, to be close to organic practices.

Downy mildew is also being examined, due to its harming of Eastern U.S. winegrapes. Because of an overly wet June and early July, Fles said 2024 was a difficult year across the board for Michigan growers battling the problem.

Fles saw the disease break through the coverage programs in synthetic and organic blocks trial programs and a small amount more in the SARE treatments of the organic blocks. However, the damage wasn’t anything to the point where he considered abandoning the treatment and going with a synthetic.

“Even though we’ve seen a little bit more downy mildew over there, it’s just not an economic problem yet,” Fles said. “It’s a way for us to look at these products and see if it’s something that we can apply farm wide in the future. I think some of them could be pretty promising. We see a little bit more breaking through on the organic soft pesticide plots than we do the conventional plots, but neither plot is considered worrisome yet or out of control. They’re both manageable at this point.”

Enviro management

Shady Lane’s philosophy is to manage, not control, the ecosystem. 

“We’re not looking to go in and clear cut and mow like a golf course and have everything very neat and clean all the time,” Fles said. “We certainly don’t want a lot of weed pressure, but we’re not going to nuke something just because we have some weeds.”

Fles’ practice is to question if a particular weed, insect or disease pressure is present and if it’s causing economic or non-economic losses. He may sacrifice a small amount of fruit that might not significantly impact the overall operation to forgo the expense of a broad spectrum insecticide wipe out or omitting a particular chemical.

Investing in cover crops, including milkweed, alfalfa and vetch, and allowing a diverse insect population to include predators that can omit broad spectrum sprays that don’t harm predators, which are more sensitive to applications, can also help reduce crop protectant use.

“Can we let that system kind of control itself? We’re always doing IPM to make sure we don’t have a breakout issue, because we do have to be economically viable,” Fles said. “A loss cannot be an economic loss. That’s been discussed for years. We got this grant to help us push into testing some newer things on a bigger scale.”

“Overall, the study was a success and we will look to implement some of the treatments this year,” Fles said.  

Because northern Michigan’s climate is similar to other winegrape growing regions in the Midwest, New York, Pennsylvania and Ontario, Canada, Fles said other growers, including those in Indiana, Wisconsin and Minnesota, could benefit from the research data.

Though Shady Lane’s agricultural heritage traces to the late 1800s as a cherry and peach grower, the family-run company began planting winegrapes in 1989 north of Traverse City, Michigan.

Doug Ohlemeier, Assistant Editor