- Agricultural Services
- Shelterbelt Program
The 2023 sale is now closed. You can find out more about the trees that were sold and find some helpful planting information in the catalogue below.
Winter damage to evergreen trees
By Toso Bozic, P.Ag
Springtime needle discolouration on previously healthy evergreens is often a result of some form of winter injury.
There are many reasons why evergreen trees and shrubs turn brown and change colour or lose needles. Many environmental conditions such as winter desiccation, salt, frost, drought, flood, soil deficiency and many others environmental factors are sometimes the cause of needle and leaf discolouration and not necessarily insect or diseases.
The key to correctly diagnosis of evergreen browning is careful tree or shrub examination. You may start with branches as colour change of the foliage may be the most obvious symptom.
Following branches examination next thing to check are the roots and trunk as they may give clues as to the exact cause of the problem. If tree is large using binoculars you may perform careful inspection of the tree crown to see if there is any physical damage by porcupine, birds and hail.
The next examination should be performed on the ground to look for any roots and trunk damage but also possible soil compaction, salt and chemical damages may also be necessary to find the possible reason for the discolouration.
Winter damage on coniferous and its severity can look different depending on tree the species.
Cedar leaf scales fade from green to light tan or reddish-brown while needle tips of spruce and pine turn brown. Winter damage may occur on different part of trees and affect a just few branches, at the treetop, on one side or even the entire tree. If you see winter burn on the north side of the plant you know that the wind was the major culprit; more often the most severe damage is on the south side and the sun was the major culprit. The tree could lose most of its needles and die.
It is very important to keep in mind that many trees and shrubs even after losing many needles may survive winter damage and recover after few growing seasons. You need to know if it is just the needles that are dead OR if the buds are also dead.
➢ If it is just needles, the tree and shrub will survive and maybe look a little sparse for a year.
➢ If the buds are green and alive trees and shrubs will grow out of it.
➢ Don’t trim the dead branches off now you may be also trimming off live buds.
➢ If by early June the buds have not started to grow you know you have a dead branch to prune off, or, in extreme cases, a dead tree.
➢ The best way to find out if branch is dead or alive is using following simple method. If tree branches are still bending and green the will flush out and new needles will grow back. If tree branches snaps- they are dead and no new growth will occur.
Winter hardiness as well as plant variety, soil drainage, location and environmental conditions are some factors to consider for tree selection choice regarding to winter damages on trees and shrubs.
Winter injuries can include:
Winter desiccation –is caused when water leave the tree needles faster than it is taken up. During winter, coniferous needles still lose a miniscule amount of moisture into the air. Meanwhile the root system freezes in the soil and cuts off water supply to the tree. Water loss is greater on windy days and mild sunny days. Heat from the sun increases the temperature of the air causing the stomata to open and lose that water. This injury can damage or be deadly to many species of coniferous trees
Sunscald – is happened when winter temperature fluctuations cause injury by damaging the bark of hardwood trees. It rarely kills the tree, but the damaged bark then becomes an entry point for insects and disease. Young trees with thin bark can suffer from sunscald, but many types of fruit trees, as well as ash, oak, birch and willow are also affected.
Cold temperature damage – is happened when high fluctuations in temperatures during the winter months causes this damage, and not a prolonged winter. In Alberta we experience a temperatures shift from – 40 C to 10 C relatively quickly. Generally dry soils are more likely to damage roots than soils that contain a good moisture supply. Root injury may be worse during winters with little snowfall. Winter root damage may not be noticed until the following summer when the plants suddenly turn brown and die
Tips to minimize winter injury
• Water in the early in the spring once the ground thaws.
• Consider fertilizing trees following harsh winter conditions, but stop using nitrogen or any other fertilizers after June 30.
• Use mulching to keep moisture around trees. Wood chips – five to 12 cm (four to six inches) thick – will keep moisture longer in the roots zone.
• Don’t prune tree branches with dead needles until June 30 – if after this date there is no new growth you may perform proper tree pruning and remove dead branch
• Use hardy plant varieties recommended for the specific horticultural zones of the province.
• Do not plant trees and shrubs around near buildings or other reflective structures.
• Do not wrap evergreens with burlap or plastic. Warm and sunny winter days will increase the internal temperature. This high temperature may damage warmed tissue when severe cold follows. Plants wrapped this way may also break dormancy.
• First help is to water evergreens in the fall. Adequate fall watering is the most beneficial for the tree. A slow water flow around the trees’ drip line for several hours will provide enough water for those roots to survive winter and early spring.
Picture 1: Winter desiccation on spruce (L) and new growth among dead needles (R)
Picture 2: Winter damage on cedar (L) and two years later cedar recovery (R)
In 2012, the Federal Government announced that it would be ending the PFRA Shelterbelt Program. This shelterbelt program was established to secure the rehabilitation of the drought and soil drifting areas as well as to promote soil conservation in the Provinces of Alberta, Manitoba and Saskatchewan.
In 2013, the M.D. of Bonnyville recognized its environmental importance and made a decision to continue with its own shelterbelt program. There are many benefits to planting trees, these include; slowing the wind which promotes moisture (by snow trapping) and decreases soil erosion, reduces wind damage to crops, increases pollinator and wildlife habitats, improves safety in winter travel due to reduced snow drifting and wind icing and finally increases property value through its aesthetics. We launched our program in 2014 with 6,000 seedlings available for sale to M.D. residents; with the popularity of the program we have since increased these numbers to nearly 10,000 seedlings annually.
The 2023 Shelterbelt Sale will open March 7, 2023 at 10 a.m. Trees will be available to order only through our online store.
Please note - while every effort will be made to fulfill order requests, we cannot guarantee all seedlings will be available at time of purchase. This sale is on a first come, first-serve basis.
The sale will officially close April 15, 2023.
Click here for more information on Shelterbelts in Alberta.
For more information on the program, call 780-826-3951.
Want to know what's at the root of successful planting? Click here.