Protect Your Tree During the Winter

For the most part, trees are able to take care of themselves pretty well.  However, since we take them out of their native environments and plant them where they may, or may not, have grown by themselves, there are a couple of things we can do to help them out on a seasonal basis.

Flat tree guard on oak

Illustration of using the flat tree guard tied loosely around the trunk.   © 2017 McNeill’s Tree Service

If you live in an area that actually gets winter, you know, cold temperatures, snow…that kind of thing, you need to consider protecting your trees’ trunks.

The candidates most likely to need this are young, newly transplanted trees.  Why?  Because their bark is thin.  Thin-barked trees are particularly susceptible to sunscald which is an environmentally-caused, abiotic, injury which can be seriously damaging.

Sunscald 20180206 (2)

The problem is created in the winter when the sun is lower in the sky and typically occurs on the south and southwest sides of trees.  The sun heats up the bark, the sap in the cambium flows, the sun goes behind a cloud or sets creating a sudden drop in temperature which can cause lethal freezing.  The damaged tissue is now susceptible to pathogenic organisms as well as having sustained the initial physical injury.  The damage is seldom seen for months if not years as the dead and dying bark does not slough off the tree immediately.  When finally noticed, this is seen as a “sudden” event by the homeowner but the damage actually occurred in the past.


There is no “cure”.  (See Blog on Trees Don’t Heal, They Seal) Prevention, though, goes a long way.  In late fall, install a protective shield on the south/southwest side of the trunk.  It may go all the way around the trunk if using one of the white tubes sold for this purpose.   If your tree has grown too big for the tubes (generally sold in 2” and 3” sizes), you can use flat, white corrugated protectors and tie them on.

Tree guard tubes2
Two sizes of tree guard tubes. Both come in the longer length, the wider one has just already been cut to fit a tree. © 2017 McNeill’s Tree Service

Whereas this is generally only necessary for young trees until their bark is sufficiently thick enough to withstand normal winters, there are a few trees that remain susceptible their entire lives.  Species such as Mountain ash trees, Sorbus spp., and the extremely popular Autumn Blaze maple, Acer freemonii, ‘Autumn Blaze’, are two examples.  Protection for trees which stay sensitive to sunscald can be accomplished by planting understory shrubs and perennials on the south/southwest side of the tree which will give it winter protection as well.

© 2017 McNeill’s Tree Service

Trees Don’t Heal, They Seal

Trees cannot regenerate tissue over a wound as humans do.  They seal off the injury and encapsulate it, hopefully stopping pathogen entry or progression in the process.  But the wound is always there and visible on the inside if not also from the outside.

This is why responsible arborists try to take as much care as possible to minimize wounding caused by pruning.  Because, technically, all pruning cuts are wounding the tree.  But then so is the swing set attached to a limb, the bump from the car, the bicycle leaned against it, the dog tethered around the base, the lawn mower hitting it every time you mow, and don’t even get me started on weed whacker injuries!

Every poster, sign, birdhouse, decoration affixed to a tree is injuring it to one degree or another.  Cats mark the trunks with their claws, birds peck holes as they go for larva under the bark or accessing sap exudations, tapping to produce maple syrup, the list simply goes on and on.  In fact, I often say, trees live in spite of us, not because of us.

When a tree sustains an injury, an air embolism is created.  The tree responds by trying to contain the damage this will cause by initiating chemical responses of various strengths, containing it from progressing up and down the trunk (axially), into the center of the tree (radially) and sideways (laterally).  There is a more powerful reaction produced as a barrier which inhibits disease or dysfunction from extending out into new wood formed after the initial injury.

Arborists will know this sequence by the acronym CODIT, Compartmentalization of Decay in Trees, as initially described by Dr. Alex Shigo, with the boundary zones, Walls 1, 2 and 3 and the barrier zone of Wall 4.

Dr. Dirk Dujesfieken has described this process further and CODIT is now being referred to as Compartmentalization of Damage in Trees.  Discussion of the CODIT Model and the CODIT Principle are lengthy subjects and topics for future blogs.

© 2017 McNeill’s Tree Service

GET ACQUAINTED WITH McNeill’s Tree Service

Welcome to McNeill’s Tree Service website.  Our company was created by my husband, David, in 1985.

Born in Massachusetts, David had always had a passion for being outdoors and climbing trees.  More than once as a child, his mother found him high up in trees on their property.   Upon the family moving to California in the 1960s, that passion became his vocation when, as a teenager, he was taken under the mentorship of Ed Hobbs, an arborist in the Bay Area.  David was a natural.

We moved to Montana in 1984, and David soon hung out his shingle, letting it be known he was an experienced arborist in residential tree care.  Wanting to keep the company small, I joined him in the field as ground support.

As time passed, we developed a reputation for quality work at reasonable prices.  At some point in time, I realized David’s passion had become mine and decided to pursue certification through the International Society of Arboriculture (ISA) program for Certified Arborists.  Passing this test opened the dam to craving more knowledge regarding trees.  Taking on-line courses through Dakota College at Bottineau, North Dakota, I gained a diploma in Arboriculture and Urban Forestry Management.  At the same time, I took and passed the test for the highest certification ISA offers:  Board Certified Master Arborist (BCMA).  This gave me the distinction of becoming the first BCMA in Montana.

David and I share a thirst for ongoing education and knowledge on anything related to trees and soils.   I have been pleased to be invited to speak at numerous clubs on all aspects of tree care and health, guide tree walks, and have presented at the Tree Care Industry Association (TCIA) EXPO, our national arborist’s association annual conference, speaking on the importance of soil health in the residential setting.

Information on tree care is readily available on the Internet and in books.  But the sheer volume of information, often contradictory, can be confusing and frustrating to the home owner as well as to many arboricultural professionals.   It was the desire to help make sense of it all that was the driving force behind initiating this website and blog.

I look forward to sharing articles, new information, and answering questions in the time to come.

Sylvia McNeill, ISA-BCMA RM-7117B

McNeill’s Tree Service