Blog : Winter Pruning Protects Trees Facing New Threats 

By Mary | Jan 24, 2014 | in

Winter is the perfect time to invest in preventative tree care that will help keep trees healthy and green all spring and summer long and reduce the potential for costly winter storm tree damage and even extended power outages.

“Because the leaves are gone, we have an opportunity to clearly see the structure of a tree, and identify what should be removed for its health,” according to Portsmouth arborist Micum Davis of Cornerstone Tree Care. Cornerstone’s Davis is sometimes referred to as the Seacoast’s “tree whisperer”.

“The dormant season is also the best time to trim a tree from a biological standpoint, in large part because harmful fungi are also currently dormant,” he says. 

Winter structural pruning gives trees a head start in realizing their ideal form aesthetically and architecturally.  Ignoring the internal structure of a tree can lead to rubbing wounds, unseen hazards, branch failure, fungi prevalence, and premature tree failure and removal. When a rubbing limb is removed early on, it conveniently allows the tree to focus its resources on expanding those healthy and necessary limbs which contribute to the tree’s overall strength and beauty.  Experienced arborists have an eye for seeing which limbs will cause problems down the road.  A precise nip here and cut there can make a world of difference in the long run.

That kind of preventative care is particularly important today, as climate change, disease, and invasive species combine to pose new threats to local tree species. 

“I’ve definitely noticed an increase in storm related tree failures, as well as in tree diseases,” Davis reports. “Changing weather patterns are affecting trees, that is certain. Many harmful insects and diseases are controlled naturally by the cold each winter, but when you have a mild winter, you don’t experience the kind of freeze necessary for that effect.” 

The hemlock woolly adelgid, an invasive Asian insect, is now infesting hemlocks in New England. It arrived in the Pacific Northwest in 1924 and moved its way east.   Although the cold we’re seeing this winter should help reduce the adelgid population, warming trends over time have allowed their continued expansion north and east. 

“The hemlock woolly adelgid is currently ravaging hemlock trees in our region,” as Davis puts it. “It’s a bug. It bites the twigs, sucks the sap and feeds. An infested tree will have many thousands of adelgids, whose combined effect will result in mortality within 3-5 years.  If people want to keep their hemlocks, they need to monitor their trees and take appropriate action if they find adelgids.  We can’t save every hemlock, but with monitoring and treatment we can preserve the most important ones."

The species' woolly appearance makes it easy for anyone to spot. “I look for the little cottony balls they live in,” Davis says. “They construct them where the needle meets the twig,”  

Globalization is largely responsible for the importation of new threats from abroad. 

“The Asiatic Long Horn Beetle was first introduced in Brooklyn,” Davis points out as one example. “It arrived in wooden shipping pallets from Asia. The only way to get rid of it is to cut down the tree and destroy it. Because of the potential devastation with which this insect threatens our hardwood forests, both federal and state laws authorize officials to remove infested trees, whether publicly or privately owned.  A 2008 outbreak in Worcester MA resulted in the mandatory removal of 28,000 trees.  You can only imagine the outrage of residents!”  Davis recommends that residents get educated on the Asian long horn and can do so on Wikipedia at  

Davis says that many US ports have taken care to intercept the beetles as they unwittingly hitch a ride into the country. "Many imported pallets are now required to be treated with an insecticide, or heat treated to kill inadvertent hitchhiking insects."

Regular tree maintenance can provide homeowners with a line of defense against these emerging threats, and can also help to prevent power outages and costly property damage. 

“One of the huge reasons for loss of power is trees that have poor structure, trunk defects, or specifically white pines that have a heavy canopy,” says Davis. “A smart consumer would be wise to get a free consultation and walk around their property to assess the health of their trees and see what might threaten their property.” 

“Having preventative maintenance done to your trees is just a good idea, given that we seem locked in this cycle of extreme weather patterns,” Davis adds, pointing to the 2011 Halloween snowstorm, Hurricane Irene and Superstorm Sandy as examples which left millions of homes in the northeast without power.

“Certain trees are prone to diseases, and pruning a tree when its dormant means that the risk of damage through disease spread or a storm is minimized.  This is why fruit orchards have always had their trees pruned in winter.  The same goes for removing large limbs from hardwood trees,” adds Davis. 

Structural and deadwood pruning act as a sort of preventative healthcare for trees. 

“When you leave a dead branch on a tree it becomes a portal for decay to enter the tree’s heartwood,” Davis explains, “removing them allows the tree to seal off the site with 'wound wood,' limiting the spread of disease and the resultant loss of strength and winter is often the best time to address this."

And, typically, tree care companies are less busy this time of year. “Plus, in the winter you might get a more competitive quote, in part because tree care providers don’t have to deal with leaves and have better access with frozen ground,” adds Davis. Cornerstone is making tree care more affordable year round by offering a 10 percent discount off tree work to members of the Portsmouth-based Green Alliance, a growing network of over 100 local green businesses and thousands of eco-minded consumers connecting to build a more sustainable economy.

To learn more about Cornerstone Tree Care, click hereCheck out the Green Alliance to get a one time discount of 10% of any tree job at Cornerstone Tree Care!