MORRISTOWN, N.J. (CBSNewYork) — Trees are colorful and peaceful additions to yards across the Tri-State Area, but face many stressors that could be killing them from the inside out without anyone knowing.

Experts refer to these trees as “Zombies,” CBS2’s Vanessa Murdock reported Monday.

Some claw their way out of the ground, while others stand and wait for Halloween. That’s when these Zombies might strike. But, experts warn of the living dead all around us that could cause serious harm at any time. Zombie trees look alive, but are actually dying on the inside.

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“Zombie trees are a thing, living, but they are just infected,” said James Campbell of Morristown, New Jersey.

“This was an accident waiting to happen,” said Jason Reitter, district manager of Davey Tree Expert Company.

Reitter said he visited Central Park of Morris County one week ago.

“This tree was here, stone-cold dead,” he said.

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Looking at the decay left behind, the tree in question was obviously dead. In many cases, though, a dying tree is only apparent to an expert. Look up at the canopy of the tree nearby and it looks healthy enough. But then look down.

“You can literally the crack that is opening up in this tree and kind of spiraling through the tree,” Reitter said.

You can see right inside, solid trunk turned to dust.

A Zombie tree.

Reitter said he has spotted more of them this year than years’ past, adding pests and weather are to blame.

“I have seen a lot of root rot,” he said.

When the ground becomes saturated due to excessive rainfall, the tree’s oxygen supply gets cut off and it drowns. High winds also wreak havoc on cracking trees.

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There may be a substantial crack in the tree, decay goes down in it and then starts this whole spiral of decline.

When it comes to pests, the spotted lanternfly leaves a mark, but the Emerald Ash Borer destroys.

“I’ve seen plenty of ash trees that could be considered Zombie trees,” said Lori O’Connor of Chester, New Jersey.

Murdock saw one in Morristown.

“Within probably I would say in a year to two, this tree will look like the other ones,” Reitter said.

But it poses a threat now. The Emerald Ash Borer is at work weakening the tree.

With Zombie trees lurking, when should you call an expert?

“Not right before the storm, hoping you’re going to be able to get something fixed,” Reitter said.

Reitter advises residents to get a good arborist and meet with them annually. Some Zombie trees can rejoin the living.

Fungus and disease can also create a Zombie tree. If you spot a mushroom growing on a trunk, it’s worth getting it checked by an arborist.

Vanessa Murdock