It's getting to be that time of year where variable rain, snow, ice and everything in between affects our travel times as well as our trees. Last December we had a very heavy snow mid-month that created the issues seen above with Eastern arborvitae
(
Thuja occidentalis). In many cases, bending of branches caused by snow and ice will be alleviated as the snow melts. Many trees will recover from even severe bending of the branches. There are mixed recommendations on whether to brush snow/ice off of woody plants (particularly evergreens) to minimize damage. If this is done (at all), it should be done gently by pushing branches upwards to shed snow, not brushing snow downward which may increase chances of breakage. However, there is a "point of no return" that was reached last year. Note the summer shot directly above and to the right with remnants of that winter bending still quite evident. In some cases, gentle staking and straightening of the branches in need of correction can be effective (particularly with younger specimens) although removal is sometimes the only option if there is more evident damage. Below is Janice's Callery pear (
Pyrus calleryana) that split a couple years ago in a heavy snowfall. Of course, the physics of wind, snow loads, etc. can lead to this type of failure but there are other factors to consider such as the form and structure of the individual specimen. The species of tree is a big factor too and the Callery pear is a good example as it is notorious for weak branches and crotch connections. Our pears in the main parking lot have suffered each winter with breakage and cracking which becomes more prevalent with older age as well.
Our spring clean-up efforts always include picking up branches throughout the gardens that have been shed during the winter. In some cases, snow and wind helps thin out the "deadwood" up in the canopy and may even take out a previously unnoticed hazard branch. Winter shedding of these branches by Mother Nature has, obviously, less of a chance of injuring staff or visitors here at the gardens. Of course, winter weather can damage, deform or destroy choice specimens and in the worst weather situations, damage avoidance is impossible. However mitigating the damage by proper selection, pruning and maintenance is possible. I ran across two websites that may be of interest that further discuss this topic. Check out
http://urbanext.illinois.edu/icedamage/ from the University of Illinois and
http://www.extension.umn.edu/distribution/horticulture/dg1411.html from the University of Minnesota for more information. Below is a upright Scotch pine (
Pinus sylvestris 'Fastigiata') at my parents house in the Chicago area. This narrow evergreen does not "shed" snow well and is prone to breakage (as evidenced by our three poor looking specimens at RBG). My parents use this ribbon to tie up the branches lightly and provide extra support during the winter months. It has been very effective (and festive!) thus far.
(Thuja occidentalis). In many cases, bending of branches caused by snow and ice will be alleviated as the snow melts. Many trees will recover from even severe bending of the branches. There are mixed recommendations on whether to brush snow/ice off of woody plants (particularly evergreens) to minimize damage. If this is done (at all), it should be done gently by pushing branches upwards to shed snow, not brushing snow downward which may increase chances of breakage. However, there is a "point of no return" that was reached last year. Note the summer shot directly above and to the right with remnants of that winter bending still quite evident. In some cases, gentle staking and straightening of the branches in need of correction can be effective (particularly with younger specimens) although removal is sometimes the only option if there is more evident damage. Below is Janice's Callery pear (Pyrus calleryana) that split a couple years ago in a heavy snowfall. Of course, the physics of wind, snow loads, etc. can lead to this type of failure but there are other factors to consider such as the form and structure of the individual specimen. The species of tree is a big factor too and the Callery pear is a good example as it is notorious for weak branches and crotch connections. Our pears in the main parking lot have suffered each winter with breakage and cracking which becomes more prevalent with older age as well. 
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