Scattered Balsam Fir Mortality Linked to Spring Weather Event

Oct 13, 2020

The needles turned reddish brown on Balsam Fir tree that died in the spring 2020 mortality event.
Credit Wisconsin DNR

There’s no shortage of Balsam Firs in the Northwoods.

The evergreen tree makes for a great Christmas Tree and traditionally grows well in our region.

This spring, seemingly random balsam firs scattered throughout the state died off.

“It was kind of a sudden mortality. The trees went from green to a deep brownish red very quickly, within a month this spring,” said Wisconsin DNR Forest Health Specialist Linda Williams.

Williams said a similar die-off happened in 2018.  In both cases, weather is likely to blame.

“On April 15th, all around the state we had very, very cold temperatures and then within a couple weeks it bounced back up to 70s-type temperatures. That’s a pretty dramatic change for trees. We suspect that that’s probably related to balsam fir reacting the way they did and dying,” said Williams.

Counties shown in blue had reports of sudden balsam fir mortality this spring.
Credit Wisconsin DNR

The good news is not all Balsam Firs died off.

And it wasn’t a bug like the spruce bud worm that could lead easily lead to more trees dying off. A tree killed by the spruce budworm will lose all its needles.

“With our spruce budworm outbreak, we probably have a few more years of that caterpillar doing some additional damage to these trees so we could continue to see some mortality due to that,” said Williams.

This mortality event also seems to be limited to the spring.

The bad news is there is no history of mortality event like this before 2018 and now we’ve had two in two years.

Williams said it could mean the species of tree may be susceptible to climate change.

“Weather fluctuations that we see in the spring we believe is what’s driving this mortality event with the Balsam Fir,” said Williams. “Perhaps it’s related to changes that we’re seeing some of these impacts now, but we can’t really make that determination until we’ve had a much longer period to look at this.”

While the dead trees could be found in just about all parts of the state, it seemed to be more common in the northern and central parts.