What A Winter It Has Been!

There is no doubt that this past winter was a cold one.  Suffering through the polar vortex, below freezing temperatures and icy cold winds had us all wishing for warmer weather.  Unlike the rest of us, our trees were not able to retreat indoors and had to withstand Mother Nature’s brutal force.  Although winter may be over now, you might still see some lingering effects of the wicked temperatures and winter storms.

Winter Burn

You may have noticed that your evergreens are not green anymore.  If the needles have started to turn brown or yellow, it doesn’t necessarily mean the tree is dying.  The cause of spring browning of needles may be disease related, however, after this year’s extreme winter, it is likely just a symptom of winter burn.

Although the temperatures may have been cold, evergreens and shrubs enjoyed the warmth of the sun’s rays all winter long. This sunshine causes evergreens to lose water vapor through early photosynthesis.  To replace the water that they have lost, needles pull water up from the tree’s roots.  Therein lies the problem.

When the ground is frozen, the tree’s roots cannot absorb water and the needles become dehydrated.  Without a sufficient water supply, the tree cannot complete the photosynthesis process that gives the needles their rich, green color.  When the weather becomes warmer, the rate of evaporation increases, resulting in drying and discoloration of the tree’s needles.

Yellow or brown needles caused by winter burn are generally found on the side of the tree or shrub that faces the sun and/or the side exposed to the wind.  This is where the rate of evaporation is the greatest so the amount of discoloration will also be increased.

Although it may not look pretty, in all likelihood, the tree or shrub is not dead.  Check the branches by lightly scraping off the bark. If the tissue below remains green and pliable, the tree or shrub is not dead.  Simply watering the plant will provide the essential material to allow new buds to begin their spring growth.  It may take some time, but you will eventually see green needles again.

To protect your trees, especially young evergreens, from winter burn, arborists recommend having your evergreen trees and shrubs sprayed with Wilt Pruf in the fall. The product guards against moisture loss and will help to minimize the effects of winter burn.  In addition, it is important to regularly water evergreen trees and shrubs so that they have an ample water supply going into the winter season.

Frost Cracks

Another lingering sign of the frigid winter temperatures is cracks and splits along the side of trees.  These frost cracks are caused when the inner and outer wood in the tree’s trunk expands and contracts at different rates as the temperature changes.

Wisconsin winters can be especially finicky, with relatively warm daytime temperatures suddenly dropping below zero when the sun goes down.  When this happens, the outer wood of the tree contracts rapidly.  The inner wood, however, is protected by the outer layer and is able to better retain heat.  Since the outer wood is contracting much more quickly than the inner wood, the force causes the outer wood to crack.  This cracking is usually accompanies by a loud snap.

Frost cracks often occur on trees where the trunk has been injured in the past due to improper pruning, lawn mower impacts, string trimmer damage, etc.  They are most common on young trees with smooth bark.  The good news is, these cracks do not seriously hurt the trees and often close on their own.  If damage does occur, simply remove any loose bark from the edge of the crack with a sharp knife.  For trees with large, serious cracks, professional arborists can also bolt the crack shut.

Animal Damage

As the snow melts away, you might start to see that bark is missing from the bottom of your trees.  If the affected area is below the winter’s snowline, it could be a good indication that your yard is infested with voles.

Voles, also known as meadow mice, can cause severe damage to trees and shrubs. They construct surface runways under the protection of the snow cover, as well as underground tunnels, throughout large areas of land.  With rapid rates of reproduction, vole infestations become more and more difficult to control the longer they go untreated.

Throughout the winter, these pesky rodents gnaw at the bark and cambium of trees and shrubs, removing it on all sides.  Trees and shrubs that have been damaged by voles may exhibit signs of disease or insect infestations including dead or disfigured branches.  Infestations of voles, as well as damage caused by rabbits and other animals, may eventually kill the tree or shrub.  Newly planted trees and shrubs are more likely to die due to animal damage. 

To control a vole infestation, it is recommended that property owners use traps or toxic baits.  Mouse traps bated with peanut butter can be used to control small populations.  For larger infestations, rodenticide blocks and toxic grains designed for vole management are the most effective.  We suggest that rodenticides be protected so that pets or unintended animals do not ingest the poison. This is easily done by placing the chemical block into a 15 inch long piece of PVC pipe and placing the pipes in areas of active feeding.

For questions or help regarding your trees or to schedule a measurement for treatment, please contact First Choice Tree Care at 262-242-1274 or visit www.firstchoicetreecare.com.