What are "zombie trees" in Vancouver and how to identify them

Arborists are alerting Vancouver property owners to a nightmarish problem this Halloween season known as “zombie trees.”

Vancouver arborist Scott Gardner of Davey Tree says zombie trees often form due to excessive drought followed by heavy rainfall.

“I know in Vancouver it rains so much that people don’t really think too much about it when summer is around… but the excessive drought trees experience causes them to run out of stored energy, and then they will die,” said Gardner.

Where do the trees get their nickname from? They appear alive from the outside, but they’re actually dying from the inside out.

One dangerous aspect is that while the tree appears healthy to a homeowner because of its leaves, it actually has some significant problems.

A huge tree fell in East Vancouver during a 2022 storm (Kath Will)

Gardner says that broken branches in the tree’s upper canopy that can fall from high heights are the most hazardous to humans and property, especially when the winds start to blow this time of year.

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Gardner explains that arborists use many advanced tools, such as sonography and route mapping, to diagnose each situation and identify the cause of the decay.

“We can spot things that the average homeowner wouldn’t spot because the things you may not think are hazardous might shock us,” says Gardner.

He added that the best tip he can offer to keep your trees from becoming undead is to keep them healthy in the first place.

Gardner recommends watering your trees in the early spring and adequately maintaining the branches with regular trimming and refraining from topping the trees, which means cutting the top branches. Topping trees can create multiple new growths at the top that will cause the tree to fall.

GotKo/Shutterstock

Some trees are saveable, but before acting on anything, it’s best to get a professional to assess the situation instead of taking matters into your own hands.

If you’re looking at the tree and something looks abnormal, such as huge cracks and mushrooms growing, that’s a sign to call the professionals.

“So depending on what kind of zombie tree it is, some of them can be like those zombies that are crawling at you, but they don’t move fast enough to get you, but if it’s a zombie tree with a rot at the base, that’s the one that’s running at you,” says Gardner.

Despite zombie trees’ characteristics that make them potentially dangerous, they don’t have to cause fear and panic.

Properly maintaining your trees and getting the right professional advice can allow you to enjoy them during any season.