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Climate change threatens central Illinois maple syrup production

The maple syrup evaporator at Funk's Grove is used to concentrate sugar from sap.
Charlie Schlenker
The maple syrup evaporator at Funks Grove is used to concentrate sugar from sap.

The largest maple syrup producer in Illinois may not have a future as global climate change progresses.

Funks Grove Pure Maple Sirup has been in business since the 1890s. Debby Funk is part of the fifth generation of the family to tap maple trees in McLean County south of Bloomington-Normal off Route 66. They have about 4,000 trees on 500 acres of land.

"We don't know what is going to happen in the future, if it is even going to be possible to make maple syrup in this area," she said.

Funk's Grove Pure Maple Sirup has been operating since the 1890s as a family run business.
Charlie Schlenker
Funks Grove Pure Maple Sirup has been operating since the 1890s as a family-run business.

Average production at Funks Grove is about 2,000 gallons of syrup. This year it was 1,600, produced mainly in February.

"It was a little disappointing," Funk said in a WGLT interview. "We had too many days in the 50s and not enough nights in the 20s, and we ended up with less than we would have liked."

In fact, the last several years have had below average syrup production. Warm winters are good for people who don't want to shovel snow, but bad for people who make maple syrup.

"The temperature change is what makes the sap move in the tree. When it is below freezing at night the vessels constrict in the tree and that draws the sap up, kind of like a straw. And when it warms up into the 40s, that creates pressure inside the tree that allows the sap to drip out. We need the constant change in temperature to keep the sap moving," said Funk.

She said the season seems to get earlier each year. As winter temperature averages rise, Funk said the take from trees diminishes. Maple syrup producers need nights with temperatures below freezing to draw maple sap up into the tree and then warmer days to make the sap run.

"We really do have to have those cold temperatures. We need a good cold winter. The colder the winter the sweeter the sap. And then we need that period of freezing-thawing. If we don't get that then it won't be possible to make pure maple syrup," she said.

Another threat to production is if daytime temperatures are warm for a sustained period.

"If it's warm enough long enough, the buds will begin to swell on the sugar maple trees. It changes the chemistry of the sap. It's called 'buddy sap' and it has an off taste. Once the buds swell, we're done even if after that we get good freezing and thawing temperatures," said Funk.

The family-owned business makes light, medium, and dark maple syrup, but also a smaller amount of bourbon barrel-aged syrup.
Charlie Schlenker
The family-owned business makes light, medium, and dark maple syrup, but also a smaller amount of bourbon barrel-aged syrup.

Funks Grove Pure Maple Sirup is the furthest south and west syrup producer in Illinois and perhaps in north America.

"There are just not that many sugar maple groves in Illinois," said Funk.

It is a midsized producer across the industry, she said. Canada and the northeastern U.S. have the largest producers.

There are three grades of syrup. Light syrup comes from the early part of the season and has a higher natural sugar content. Medium comes from the middle part of the tapping season and dark syrup comes at the end. It has less sugar and to concentrate it you have to boil the sugar longer to reduce the sap, which caramelizes the sugar and makes it darker and stronger tasting. (By the way, you should spell the "syrup" in Funks Grove Pure Maple Sirup with an "I" instead of a "Y" out of family tradition.)

Funk said they do about 20% of their business online. Route 66 is a big draw to the store in Funks Grove. They sell to just a few places: the McLean County Museum of History in downtown Bloomington, Green Top Grocery in Bloomington, and the Garlic Press gift store in Normal. She said they usually sell out by mid-August.

The worst production year for Funks Grove Pure Maple Sirup was about 800 gallons of syrup. Funk said there was a sustained period in February with temperatures in the 70s and nighttime temps above freeing prevented the sap from running. In contrast, the highest annual production was 3,000 gallons, Funk said.

A typical production season historically for Funks Grove would be from mid-February to mid-March. For now, Funk said they can adjust to climate change by starting to tap trees earlier, maybe in January instead of a month later. Even that adjustment is not a sure fix, said Funk, because there tend to be fewer January days that are warm enough to cause the sap to run. That is a judgment call based on long-range forecasts, she said.

"We have some friends in Wisconsin who are experiencing the same difficulties with it getting too warm too soon for them," said Funk.

She said producers in other points north of central Illinois are having to tap earlier as average winter temperatures rise. Producers in more northerly locations are collecting sap now because their season is later than it is in McLean County.

Some climate change scholars suggest Illinois is heading for an average climate more like east Texas. If that happens, Funk said her family's multi-generation business would end.

WGLT Senior Reporter Charlie Schlenker has spent more than three award-winning decades in radio. He lives in Normal with his family.