Zombie trees


I started writing this column on Halloween, a day many associate with ‘scary’.  So zombie trees seemed an appropriate topic right now. I had never heard the term until a friend brought it to my attention.  A zombie tree is a tree that thinks it’s alive, but isn’t, according to arborist Jay Judd as reported last week to Colorado TV channel 9 news.

OK, so what does that mean?  The tree looks alive but has a lot of internal decay.  The vascular system (plant tissues that conduct water, sap, and nutrients) is still functioning so the tree will have at least some leaves. 

The state forest service receives many calls concerning damaged trees in the fall if we have storms with heavy snow, cold temperatures, and/or wind.  We’ve already had two in Alamosa this fall.

“Some dying trees, much like the zombies in ‘The Walking Dead’ have patches of bark (or skin in the case of an actual zombie!) peeling off,” reports Michele Hollow in her lawnstarter.com blog. However, not all zombie trees have this symptom.  Here is a list of other symptoms to look for: hanging limbs; split trunks; discolored leaves and leaves with dying tips, deadwood, decay, or fungus, dieback of the top the tree; and/or insect infestations such as bark beetles.

A tree dying is natural, but with proper care a tree can last a long time.  “Trees grow and as they age, they have something in the center called heartwood,” says Jason Grabosky, professor of urban forestry at Rutgers University.  “Heartwood is the dead inner wood and there’s sapwood, which is the living outermost portion of the tree.”

According to Hollow, the main causes of tree death are insect infestations, fungal disease, and climate change (excessive heat and drought in our area).  I would also add days when temperatures drop quickly to below freezing causing internal tree fluids to freeze and break vascular cell walls.  I’ve lost two trees in my yard due to this, but in the spring, not the fall.

Often, dying trees can be turned into healthy ones. Make sure to water your trees correctly – not too much or too little. Our last, heavy wet snow did a good job of watering our year for the near future.

Use fertilizer and cover the surrounding area with mulch. Properly prune your trees or have an expert do it. “It’s also important to check the soil near the base of the tree,” Grabosky says. “Often problems start because of damage to the soil. A healthy tree’s roots need air. Heavily packed soil surrounding the tree harms the tree. Without pockets of air around the roots, you’re compromising the tree.” I’ve discussed these topics in previous Courier articles and they can be found online at AlamosaTrees.net.

If you suspect an insect or fungal infestation, you need to first identify the problem. If you have no idea, please consult a certified arborist, licensed tree expert, or your local forest service office.  In Alamosa you can go to the Colorado State Forest Alamosa District office website at https://csfs.colostate.edu/alamosa/ for more information. According to their website, the office is currently closed and personnel are working remotely, but remain available to assist the public.

If you suspect you have a Zombie tree that is beyond help you may not need to remove it.  If the tree could fall on your home, driveway, or sidewalk, you should consider removing it.  If it is away from structures and areas that people frequently use, you might want to consider keeping it as it won’t cause any damage if it falls.  Grabosky says dead trees provide home to animals.  “We need these habitats for a healthy ecosystem.  Remember, just because it’s dead doesn’t mean it’s dangerous.”

“A tree has roots in the soil yet reaches to the sky.  It tells us that in order to aspire we need to be grounded and that no matter how high we go it is from our roots that we draw sustenance.”  Wangari Maathai