ReWorking Michigan: Fruit Growers Scramble to Mitigate Frost Damage

Mar 25, 2012

Record-breaking warm temperatures this spring have coaxed fruit trees and other perennial crops in Michigan to bud weeks ahead of schedule.  Farmers are facing a much earlier growing season and several more weeks of anxiety over the threat of frost.

At Clearview Orchards in Haslett, the peach trees are in full bloom.   The apple trees are budding, and owner Phil Korson expects they’ll be in full bloom this week.

“These are Northern Spies,” says Korson.  “This would be a really late variety, so normally you wouldn’t see any green at all.  You look at this bud right here, you can see how they’re already separated?  That’s the king bloom.  It’s going to be pink in a couple of days.  It’s already got little leaves on it.  That will break apart, and they’ll be five apples there.”

Like many growers, Korson thought he had another few weeks to prune his trees, but now he’s hurrying to get ready for the growing season.

“It’s hard to believe that in March we could be this far advanced,” says Korson. “We’ve never seen this before.  In 1945, that was the last time we had this early of a spring, and it was nothing like this.  So, this is very, very, very unusual.  We’ve never seen this, never.”

The extremely warm weather has awakened perennial crops from their dormant state.  That includes fruit trees, blueberry bushes, grapevines, and raspberries and strawberries.  The more advanced they are, the more susceptible they are to damage from frost.  In Michigan, there’s a potential for frost through Mother’s Day, so for the next several weeks, farmers will be watching the 10-day forecast closely.

Greg Lang is a professor of tree fruit physiology at Michigan State University.  He says when farmers know a freeze is coming, there are ways they can add a little bit of warmth to their orchards.

“In the old days, sometimes they burned tires,” says Lang. “That sort of thing, environmentally, is no longer feasible.  But with an irrigation system, if their irrigation lines are charged  and ready to be functional, that’s one thing everyone is scrambling to do now, they can begin irrigating with sprinklers under the trees.  That helps the soil hold more heat in it, and at night a lot of that heat is radiated into the air and around the trees, as well as moving above the trees.”

Some farmers in Michigan use wind machines.  They’re small towers with big propellers on top that pull warm air down into the orchard.   Lang says just a couple of degrees can make a big difference.

“At full bloom, temperatures of about 28 or 29 degrees will damage maybe about 10 or 15 per cent of the flowers on the tree.  So, a flower can survive a little bit below freezing.  But temperatures of 27 degrees, just one or two degrees colder, can cause 90 per cent of the flowers to be damaged.  So, you have a very narrow window at full bloom.”

There’s also a long-standing tradition among fruit growers that helps protect their orchards during a frost.  Jeff Andresen, the state climatologist, explains that orchards are planted on ridges and hilltops, because frigid air drains away from high ground.

“The surface between the atmosphere and the vegetation is typically one of the coldest spots,” says Andresen.  “The cold air acts like a viscous liquid, and the colder, denser air sinks down to the surface.  If it’s heavy enough and cold enough, it will actually begin to flow like a dense liquid.  It will go along with the topography, wherever that takes it.  Growers have used this, knowing that they were much better off avoiding freezes and frosts if they were on high terrain.”

Phil Korson planted his fruit trees on high ground.  His farm is the highest point in Ingham County.   But when it comes to frost protection, Korson is philosophical, preferring to leave it up to Mother Nature.  

“It’s one of those things you can’t control,” says Korson.  “We get to 22 degrees, and nothing will save these.  No wind machine, no fire.  Nothing will save them.”

If orchards in Michigan do survive this spring without significant frost damage, then farmers will be able to take their fruit to market much earlier than usual.  That could mean a better price for their fruit and another one for the history books.

reWorking Michigan examines our evolving economy, as the people of the Great Lake State explore new ways to make a living and build a future.  A project of WKAR NewsRoom, WKAR-TV and WKAR Online.