We’re in Willowdale – Yonge/Sheppard area – We’ve lived here 25 years and the lilac predates us. This year, for the first time, its bark has been attacked – quite severely. We caught squirrels in April/May munching away at some new shoots, but now that we’re in the yard again, can see the huge damage to the bush. Is there anything we can do to protect it? We’d love to keep the lilacs if at all possible. It took us years to figure out how to prune them properly to get blooms and would hate to lose them now!
Thank you for contacting Toronto Master Gardeners with your question. It is always so distressing to see an attack on a favourite garden plant! And squirrels are both prolific and annoying when it comes to our gardens!
Squirrels attack tree and shrub bark in early spring when other food sources are scarce. With increasing numbers of these critters in our area, there may have been a shortage of food for them this winter/early spring. Squirrels also strip the bark in late spring/early summer to use as nesting material. Minimal damage will not kill the plant. The survival of your lilac bush will depend on the extent of the damage. This is ascertained by examining the stripped areas. Are large areas stripped bare? Are the stripped areas going along the branches and trunk, or are they going around the branches/trunks? If they go right around the branch, girdling it, the limb will not survive and should be cut away. The rule of thumb is that a healthy plant limb or trunk will easily survive bark stripping up to 25% the way around. There is a chance of survival with stripping from 25% to 50%, especially with care as to watering and insect/disease control. Damage that extends beyond 50% will likely kill the limb or trunk. While some sources recommend treating the wounds, most seem to favour leaving it bare and clean to optimize natural healing.
There are various suggestions for preventing squirrel damage, including wrapping the trunks in wire mesh. Squirrels are great climbers and jumpers, however, and are likely to evade such mechanisms.
Please take a look at the following links to articles on squirrel damage:
https://gardening.usask.ca/article-list-animals/animal-damage-to-trees.php
https://homeguides.sfgate.com/squirrel-stripping-bark-off-tree-kill-tree-92677.html
Best of luck with your lilacs!