CASPER, Wyo. — This past December, Leeward Tree Farm owners Kylie Cestnik and her dad, Bruce Smidt, anxiously kept their eyes on the outside temperatures and jotted down notes as a winter storm approached.
The temperatures were going down, and they kept going down. Quickly.
“It dropped 70 degrees in 24 hours, and then the next day it dropped 45 degrees in five hours,” Cestnik said. The only thing they could do at the time was hope the swaths of trees they plant and cultivate for area gardens were far enough into their winter dormancy to handle the extremes. The answers have become more clear over the past couple of weeks.
“It did some damage,” she said. “I think it killed all of our fruit trees, possibly killed [some of] our lindens, damaged a ton of spruce trees.”
It’s not just on the family farm, either: She’s also noticed something off in other Casper yards and open spaces.
“Just around town I’ve noticed a ton of red and white flowering crabapple trees that aren’t leafing out,” she said. “I’m seeing it in my own yard and around town. A bunch of Aspens [are struggling] too.”
Some Elm trees around town appear to be struggling this spring, but Cestnik says the Ash are doing fine.
The trees Leeward grows are designed for Wyoming’s rough climate, and they usually thrive.
“It’s not that these trees aren’t cold-hardy, it’s just they can’t take a temperature fluctuation that quickly,” she said.
Katy Hallock, a park supervisor and forester for the City of Casper, echoed Cestnik’s observations.
“Most of the trees we’ve seen possible damage to are the pine trees around town, the evergreens,” Hallock said. “It’s still early in the season, so we are seeing a lot of needles starting to push out, so we’re hesitant to say there’s been a lot of tree death.”
“We feel like the next three to four weeks will be critical to see how much impact there’s been on evergreens,” she said, adding that Juniper bushes are also taking longer to come back.
In the case of mature trees, Hallock says the temperature swings from this past winter are only part of the reason they’re struggling this spring.
“We’ve also been in a drought over the last 10 years, so these trees were stressed, and had been stressed before we had these significant freezes.”
Casper’s older trees were hit hard during Storm Atlas in 2014, where wild temperature swings stressed trees that had endured structural stress after heavy early snows the year before. Quite a number of them eventually had to be removed.
Hallock says another issue this year has been the consistently cold temperatures, meaning that the ground has stayed frozen longer than usual, making it difficult for trees to benefit from the higher snowpack.
“We got a significant amount of snow, but when the ground is frozen like it was, it takes time for it to thaw out and for the moisture to actually get down into the roots,” she said.
Cestnik and Hallock say that the next few weeks will be critical, and time should give them a clear picture on how much damage has been done.
“We’re very hesitant to say that we’ve had significant death in our urban forest,” said Hallock. “We need to give it more time before we know for sure how much damage there is.”
It’s also far too early to start pulling out trees or bushes that might seem to be dead.
“What I’m telling my customers right now is to just leave their trees, don’t do anything to them,” Cestnik said. “I’ve seen trees sit like this and try to leaf out in July.”
Both experts say that stressed trees should absolutely not be fertilized or treated in any way over the next few weeks. Any pruning or trimming should also be avoided for the time being.
“I would just be sure you’re giving the trees extra water,” Hallock said.