There was a pretty interesting article in yesterday’s Star Tribune about the feared impact of the Emerald Ash Borer. That’s a close up of the critter in the photo on the right. To the left of that photo are two photos of ash trees that show the symptoms of the ash borer.
The first thing you’ll notice about in an ash tree that is home to the emerald ash borer is the thinning of the branches and leaves during the middle of the growing season. That’s not good. If you have any doubt about whether an ash tree has an ash borer problem, you can pull section of bark back and if you see the borer’s “tunnels” under the bark, you’ve probably got a tree with an emerald ash borer problem.
Minnesota cities are struggling with the emerald ash borer problem. Many cities planted ash trees to replace elm trees following the decimation of elm trees by Dutch Elm disease. Alexandria, for example, estimates that 60% of its urban forest is ash trees. It will be big issue in Minneapolis and St. Paul as well. In Eden Prairie, our City Forester told me that ash trees make up about 30% of our urban forest. But in some areas of town, ash trees are much more prevalent. In Round Lake Park, for example, about 80% of trees you see are ash. Consider the appearance of Round Lake Park with 80% of the trees gone and you’ll get an idea of what we’re worried about.
So what should cities do? Nothing and let nature take its course? Preemptively cut all its ash trees down? Chemically treat all its ash trees to protect them? We’re still trying to figure out the right course of action for Eden Prairie. Our motto, however, is “don’t panic”. We’ve had a dutch elm disease policy and tree removal program in Eden Prairie for 35 years. We still have elm trees, but we still are removing elm trees too. We believe that something very similar is in store for our ash trees. We don’t have the budget available to take them all down, but we don’t have the budget to inoculate them all either.
The best thing we can do is to make sure that we begin to plan for a species of tree to replace the ash trees when they eventually get infected and have to be removed. We expect that to happen to most, if not all of them, someday. But if we begin to replant now, in 35 years when the last of the old ash trees are coming down, we will still have a vibrant urban forest.
That’s the long term strategy, but we need to get started on it now if it’s going to be the long term solution.
