If you had a chance to catch any of the virtual Alaska Invasive Species Workshop hosted by the University of Alaska Fairbanks Cooperative Extension Service this week, it might have you thinking differently about the chokecherry.
The tree is a pretty ornamental, but the non-native species can be a problem for Alaskan forests and wildlife.
Agencies including the Department of Forestry, Fish and Game and the University of Alaska promoted planting choke cherries as far back as the 1950s, as an ornamental landscaping solution.
“And it was a good idea at the time,” said Gino Graziano, an invasive plants instructor with the UAF Cooperative Extension Service. “They have those cherries that attract birds, they’re not super tasty for us to eat, but you can make them into things.” Graziano gave a talk during the workshop titled, “Choking Out the Chokecherry.”
The trees produce attractive flowers in the springtime and generally aren’t damaged by moose in the same way that newly planted birch or apple trees often are when not protected by a fence.
Chokecherries spread around the Anchorage area heavily in the late '90s. “That’s about the same time invasive species management was starting to pick up tempo in the state, as people were starting to recognize invasive species issues,” Graziano said.
Around 2011, the Department of Fish and Game started to get reports of dead moose in people’s yards. “Turns out, after they’d eaten these trees, they died of cyanide poisoning,” Graziano said.
The reason moose don’t usually eat chokecherries is because of the potential for cyanide poisoning.
“Normally, a free-ranging animal is not going to eat so much of something that is toxic that it’s going to die,” Graziano said. “Especially in the Anchorage area, seeing how many are getting out into the forest and changing the way those forests look, people are really interested in managing them.”
There are lots of options for getting rid of chokecherries on your own land. Graziano said it all depends on what you are dealing with. “They’re tough to kill, because you can’t just cut it down, if you did, it’s going to sprout back at the stump.” Meaning you either have to go through the labor intensive process of removing the entire root system or use an herbicide to keep the tree from coming back.
If you’re looking for local examples of a chokecherry invasion, you don’t need to search any farther than Creamer’s Field. “They’re all over the place in there,” Graziano said. “They can do quite well in the Interior area.” The trees grow especially well in wet spots and riparian areas.
There are two types of chokecherries spreading in Alaska. One is prunus padus, commonly called the Canada Red Chokecherry which has green leaves at the beginning of the season that turn purple-red around late June and stay that color for the remainder of the season. The Canada Red variety has spread less than the prunus virginiana, or European Bird Cherry. “It’s hard to tell the difference between them unless you see the color change, which has also led us to be suspicious that there is probably more of that Canada Red out there than what we think,” Graziano said.
Ryan Klimstra, a biologist who manages Creamer’s Field Migratory Waterfowl Refuge, said that plans for how to manage chokecherries within the refuge are still taking shape.
One issue is that the best way to manage the invasive species is through the use of herbicides. Klimsta said herbicide use can be a tough sell because public perception is that the treatments are bad for the environment and can damage ground water systems, but Klimstra said that perception is often inaccurate and herbicides can be used responsibly and effectively in invasive species management.
Contact staff writer Sam Ferrara at 459-7575. Follow him on Twitter: @FDNMoutdoors