Why winter cold won’t stop emerald ash borer

A very cold winter can make it tempting to assume that emerald ash borer won't be a problem here. Unfortunately, Winnipeg's winters are not reliable protection for our ash trees.

Research reported by Western University in 2022 found that overwintering emerald ash borer survived the 2019 polar vortex in Winnipeg. The insects' cold tolerance was greater than earlier expectations suggested. The practical point for tree owners is straightforward: cold weather does not remove the need to monitor ash trees and plan their care.

If you have an ash tree, start with its overall condition. A healthy, well-placed tree may be worth protecting. A tree with serious structural problems or advanced decline may call for a different plan. Those decisions are easier to make before an urgent removal becomes necessary.

Watch for changes in the crown, unusual shoots on the trunk, bark splitting, or increased woodpecker activity. None of those signs alone confirms emerald ash borer, so have the cause checked rather than guessing from a photograph.

An arborist can help identify the tree, assess its condition, and discuss treatment or removal where appropriate. Keep doing that work after a cold winter. The weather hasn't made the decision for you.