Here’s how to know if you have yew
in your yard, and what to do about it
The yew plants used for landscaping in the Treasure Valley are all poisonous to wildlife, people and dogs. There is a native yew, the Pacific or western yew, that is found in Washington and Valley counties and points north in Idaho. However, it doesn’t work well for landscaping (it requires a lot of water). The native yew has trace amounts of poison but is used safely as winter food by moose, elk and deer. Here’s what you need to know to determine whether you have yew in your yard and how to cover or remove the plant:
NAME DOESN’T MATTER
Japanese yew (Taxus cuspidata) is the variety often attached to wildlife poisoning, but English/European yews (Taxus baccata), Chinese yews (several species) and Canadian yews (Taxus canadensis) also are poisonous. Japanese yew and its hybrid with English yew are the primary landscape yews in southern Idaho, said Lynn Kinter, the lead botanist at Idaho Fish and Game.
The naming can get confusing. Dennis Fix, the owner of FarWest Landscape and Garden Center in Boise, said his store doesn’t have anything labeled “Japanese yew.” Instead, you’d find names like “Irish yew,” “upright yew” and “dark green spreader yew.”
“They’re all toxic,” Fix said.
HOW TOXIC IS IT?
Yew poisoning is lethal to people, large animals such as cattle, horses and elk and pets. Small amounts can prove fatal.
“The leaves are poisonous,” Lynn Kinter, the lead botanist at Idaho Fish and Game, said. “The stems are poisonous. And the seed inside the berry is poisonous. … As small of a contact as a dog chewing on a branch of one of these shrubs can cause the dog to die.”
Kinter has one yew in her yard.
“I’m going to take mine out,” she said. “Even though I’m not in what might be a dangerous part of town (for wildlife), I do have a dog that loves to chew on sticks.”
HOW TO IDENTIFY A YEW
Yews have flat, evergreen leaves or needles that are about an inch long, an eighth of an inch wide and pointed on the ends. The female plants have red, pea-sized berries in the summer and fall that have openings on the end, allowing you to see the brown seed inside. The most similar evergreens are hemlock and spruce but they have brown cones. Hemlock needles are rounded on the end and spruce needles are skinny and sharp. If in doubt, clip a branch and take it to a garden center or other expert.
IF YOU WANT TO KEEP IT
Wrap the yew with burlap for the winter and secure the burlap with landscape staples. Make sure you secure it well enough at the ground level to keep animals out. This process is easier if you prune the shrub first, Kinter said.
IF YOU WANT TO REMOVE IT
Cut the yew down and dig out the roots. If you don’t remove the roots, it will grow back. If you can’t get the stump out of the ground, an herbicide will kill the plant — but that takes time. When you remove the plant, be sure to dispose of it at a landfill. The dead branches remain poisonous, Kinter said.
IF YOU WANT TO REPLACE IT
Yews fill a niche for an evergreen that likes shady areas. Idaho native plants that could fill those spots, Kinter said, include: Western swordfern, Oregon boxleaf, curl-leaf mountain mahogany, russet buffaloberry, oakleaf sumac and Oregon grape-holly.
Idaho native plants that aren’t evergreens but like shade include syringa, Woods’ rose, thimbleberry, oceanspray, mallow ninebark, Rocky Mountain maple, golden currant, red flowering currant, common snowberry, red-twig dogwood and highbush cranberry/mooseberry.
Non-native evergreen options could include evergreen huckleberry, dwarf Alberta spruce, false cypress and arborvitae (attractive to deer).
BOISE — Homeowner Jerry Smith and Idaho Fish and Game conservation officer Ben Cadwallader watched a mule deer eat from the poisonous yew bush in Smith’s back yard Feb. 3. They followed as the deer ran over a hill.
“And it was dead,” Smith said. “They die that fast. It was not 10 minutes and that deer was dead. … It was a frustrating situation for us because we’ve worked hard at trying to help the animals stay alive for all the years we’ve been there.”
Smith and his wife, Donna, have lived in the house in the Barber Valley for 46 years. They learned in January that the three yew bushes they planted in their front yard were poisonous after hearing about the deaths of seven elk that ingested the plant in a neighborhood near Table Rock. The Smiths covered those plants with shrink wrap and made plans to rip them out this spring.
But they didn’t realize that the transplanted bush in their back yard was a yew, a plant with many varieties — nearly all of them toxic to wildlife, people and dogs. Seven mule deer died after presumably eating from that bush, including two that collapsed in the Smiths’ yard and led the couple to contact Fish and Game.
Smith and two neighbors immediately took a chainsaw to the bush and removed it. They removed the three in the front yard, too.
“I’ll do anything I can to get the word out,” Smith said. “It’s a deadly plant and we should not have it — we should not have it in the state of Idaho at all. … It’s devastating to come out and find dead deer around your house and think you did it.”
Yew poisoning has been cited as the cause of death for dozens of elk, at least 50 pronghorn and an unknown number of deer this winter as more wild animals than usual have filtered into populated areas in search of food that isn’t covered with snow.
The elk deaths have occurred in communities from Boise to Preston. The 50 pronghorn died in one incident in Payette. Eight mule deer died last week in East Boise — the seven at Smith’s house and one near Bown Crossing.
In eastern Idaho, eight elk died last week in the Rimrock area near Idaho Falls after ingesting yew. And according to the Challis Messenger, five elk died recently on the Challis Golf Course after eating from the plant.
According to Fish and Game Information Supervisor Mike Demick, there have been a combined 85 deer, elk, pronghorn and moose killed by yew this winter compared to just 15 elk (all in Blaine County) last winter.
All of the deaths in the Treasure Valley have been attributed to landscape plantings at homes. Landscaping yews aren’t native to Idaho — most are varieties of Japanese or European/English yews. A similar problem occurred last winter in the Ketchum area, leading Blaine County to ban the plant.
Evin Oneale, a regional conservation educator for Fish and Game based in Nampa, said this is the first time he’s heard of yew-wildlife incidents in the Treasure Valley. He’s been here more than 20 years.
But as homes encroach more on the winter range of elk and deer and severe winters like this one push the animals to even lower elevations than usual, the issue likely will come up again.
“(The incidents) are in a lot of areas where 10 years ago there weren’t houses,” Oneale said. “That just gives them more opportunity to come into contact with this plant because it’s so prevalent in the landscaping business.”
Dennis Fix, the owner of FarWest Landscape and Garden Center in Boise, wrestled with how to handle yews at his business after the elk deaths. His first inclination was to stop stocking them, but he sells between $20,000 and $40,000 worth of the plants annually.
He has informed customers in the past about toxicity in relation to people and pets but didn’t anticipate the threat to wildlife, he said. He plans to keep the plant in his inventory but increase education to those who want to buy it, including signage. He also plans “more screening to prevent sale of yews to big-game zones within our city,” he said.
Fix estimates a quarter to a third of his customers have a yew in their yards. Yews are unusual among evergreens in that they thrive in partial sun and shade commonly found on the north side of properties.
“They’re not popular like a rose would be, where everyone’s got one, but they do fit a niche,” Fix said. “… You put these in the same spot as a Japanese maple or a hosta. You drop a yew in there to hold a little interest in the winter.”
2,000 years of poisonous history
It’s surprising that this winter’s yew-related deaths came as such a surprise.
The toxicity of the plant is no secret. More than 2,000 years ago, Julius Caesar wrote about a king committing suicide by yew in his book about the Gallic Wars. Yews are known as some of the most toxic plants in Europe, said Lynn Kinter, the lead botanist at Idaho Fish and Game. Japanese yews are even more toxic, she said.
Despite that, yews became popular in America beginning in the 1920s, she said.
“Maybe that knowledge got lost to some extent,” Kinter said. “Maybe people didn’t realize quite how poisonous they were.”
Blaine County Commissioner Angenie McCleary said she had never heard of yew killing wildlife before January 2016, when 11 elk died in the Hailey Cemetery. More elk died shortly afterward in The Valley Club, a neighborhood in Sun Valley.
Within a month, McCleary and her fellow commissioners made “possession, planting or sale” of several yew species a crime in the county’s unincorporated areas. The law has teeth. Violations are a misdemeanor. That means people who keep yews on their property risk up to a year in jail, though that stiff of a penalty is unlikely.
The ban isn’t meant as a punitive measure, McCleary said. In fact, the county hasn’t cited anyone for breaking the yew law and doesn’t patrol neighborhoods looking for rogue plants.
The law appears to have been effective. Despite a harsh winter that’s turned wildlife into regular inhabitants of neighborhoods and city streets, the first yew-related death reported in Blaine County occurred this week when a moose died, McCleary said.
In the Treasure Valley, yews flew so far under the radar in recent years that they were placed on the approved plant list for Harris Ranch when the development along the East Boise Foothills began in 2008. That’s a neighborhood so wildlife-conscious that homeowners pay a $100 annual fee toward wildlife projects.
“We had (the list) reviewed by all of our wildlife consultants that wrote the mitigation plan as well as Fish and Game,” said Doug Fowler, project manager for Harris Ranch.
When Harris Ranch officials were informed that yew was responsible for the elk deaths near Table Rock, they pulled it from the list. Residents have been asked to cover the plants with burlap for the winter if they’re unwilling to remove them.
Mark Drew, the wildlife veterinarian for Idaho Fish and Game, has examined some of the yew-poisoned animals to determine the cause of death. The toxin — taxine B — causes cardiac arrest, he said.
And while many poisonous substances are distasteful enough to discourage consumption, the animals Drew examined were full of yew.
“These are evergreen species — in a stark, white landscape where everything is black and white or brown, if something looks green, it probably looks tasty,” he said.
Even if the animals limited themselves to a few bites, yew could kill them. Studies show that it takes 30 grams of leaves to kill a dog and about 500 grams to kill cattle, Drew said.
“You’re talking a half cup, a cup full (for big game),” he said. “So not much.”
The animals he’s seen have ingested “cups and cups” of yew material. The stems and leaves are poisonous, as well as the seeds inside the red berries some yews produce in summer and fall.
“They die pretty quickly because their heart stops,” Drew said. “Some of those animals died with yew leaves in their oral cavities and esophagus.”
‘A minefield’ of toxic plants
Drew hopes the animal deaths this year at least lead homeowners to ask questions about their plants that they never have before.
“We don’t stop to think, ‘Is this potentially poisonous?’ ” he said. “It’s not even in the realm of possibility of questions we would ask. We just need to let people know that some of the plants used in landscaping are potentially toxic, and if you’re in a situation where ungulates (deer, elk, horses and many other species) are potentially using your yard, your neighborhood, maybe we’ve got to think about that.”
Others prefer a more drastic response. To them, there’s no place in a wildlife-loving state for a wildlife-killing plant.
Angela Rossmann of advocacy group Great Old Broads for Wilderness has spent the past few weeks calling government agencies, neighborhood associations and garden centers trying to increase awareness and build momentum toward a yew ban.
“We’re small enough that if everybody works on this, we could make it go away,” Rossmann said.
Her allies include the Ada County Fish and Game League, a sportsman group that dates to the 1920s. John Caywood of Boise, the group’s president, says wildlife is being wasted by a plant that benefits few. At the least, he’d like to see more of what Harris Ranch is doing — making the plant unwelcome in developments along the Foothills.
The elk deaths near Table Rock were tied to several properties with yews, Oneale said, including abandoned homes in the Terra Nativa subdivision.
“We just think it would be a great idea,” Caywood said, “if native wildlife didn’t have to run through a minefield of exotic, introduced, poisonous plants in people’s yards.”
Educate or regulate?
So far, local governments are reluctant to ban yews. McCleary said she’s aware of no law in Idaho similar to the one Blaine County passed last year.
Payette County prefers to use education to avoid further wildlife deaths, Deputy County Clerk Christine Poe said.
Calls from people concerned about poisoning wildlife have trickled into Ada County’s offices over the past few weeks, spokeswoman Kate McGwire said, and the county’s weed control team is hosting an online survey to find out how pervasive yews are and if people know they’re dangerous. But legal restrictions aren’t imminent.
Boise City Councilwoman Lauren McLean said she’s not ready to put an outright yew ban in place.
“Step one: Educate. Step two: Regulate,” McLean said. “I believe in my heart of hearts that this would never be intentional, so it’s a matter of getting the word out and making sure it doesn’t happen again as we see new development in the Foothills.”
The planning process is one tool the city can use to avoid yew planting in neighborhoods where deer, elk or other wildlife might wander. Most residential subdivisions don’t include landscaping plans that approve or prohibit certain types of plans, planning director Hal Simmons said. But the city could add a restriction on yews and other toxic plants to its list of standard conditions for any subdivision in the Foothills or along the Boise River.
“Any time we can cooperate, we’re having a better day,” McLean said. “But there’s a place for regulation. And, especially when plans come in front of me, I couldn’t look away if a yew were in the plans.”