In Southwest Colorado, our coldest months are fast approaching.
Allow me to remind you: In December 2015, we had 11 nights that registered below zero at the airport; January had 14 nights that went below zero and three more that hit zero. Additionally, between those two months, we also had 20 days where the temperature swing was greater than 35 degrees.
As someone who has lived in Durango the majority of his life, I appreciate those warm sunny days in the dead of winter. It’s not gray, the chance of fog and high humidity is relatively slim and there is no high of 32 and low of 28 with a chance of freezing rain.
But for a number of our trees, especially those that are thin-barked, the cold nights coupled with the large swings in temperature, snow on the ground and sun in the sky can make for a stressful winter. So for deciduous trees such as lindens, maples, honeylocusts, crabapples, poplars and most fruit trees, I recommend wrapping the trunk of the tree the first two to three years after planting. The wrapping material, which is typically made of a crepe paper-like material, is commonly found at local nurseries, and a roll can last for numerous seasons, depending on how many trees you need to wrap.
As a side note, I have never really liked wrapping Christmas presents. Actually, as I have aged, I have purposefully gotten worse at perfecting my craft. My hope is that in the next two years, my daughter, Elena, who is all sorts of arts-and-craftsy, can wrap all the presents. Even her own.
But I digress. The purpose of wrapping a tree’s trunk is because the thin-barked trees are susceptible to sunscald (also referred to as “south-side damage” because that is typically the side of the tree that incurs the injury) and frost-cracking. In both cases, during warm sunny days, the cells of the trees come out of their slumber and start moving water and nutrients through the vascular tissue. The snow on the ground only exacerbates the amount of cellular activity as it reflects the sunlight back to the trunk of the tree, warming up the tree’s tissues even more.
Come late afternoon when the sun drops, so does the temperature. Rapidly. The cells don’t push the water through their walls fast enough, so they burst. Given the fact that last winter (November to February) we had more than 30 days when the temperature difference was greater than 35 degrees, it’s no surprise that we frequently see this type of damage on newly planted trees.
The tree wrap will provide a bit of insulation but will also reflect the sunlight, keeping temperatures cool. Start wrapping the tree at the base, overlapping one-third with each turn, which will enable the wrap to shed water and keep the trunk dry. Once you reach the first branch, cut the wrap and either staple it to itself or tape it to the tree with duct tape.
Wrap the tree around Thanksgiving and remove it around tax day (think “feast and famine”) because it can harbor diseases and insects during the growing season. Once the tree starts to form a rough or calloused bark, you most likely won’t have to wrap it anymore.
Darrin Parmenter is the director and horticulture agent of the La Plata County Extension Office. Reach him at firstname.lastname@example.org or 382-6464.Darrin Parmenter