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What is the city’s plan for dealing with the smelly, invasive scourge known as “tree of heaven”? They’re worse than blackberries. I demand answers! —Future Karen
Environmental apocalypses aren’t what they used to be, Karen. Just a few years ago, we were freaking about things that might end civilization by 2100. Now that even making it to 2035 seems like a long shot, getting folks to care about longer-term threats like invasive species is like trying to convince Betty White to pay extra for a 30-year roof.
That said, few invasive species are more obnoxious than the tree of heaven. It’s fast-growing, extravagantly fertile, and thrives in situations that would make most plants look like pre-resurrection Groot. Its hardy, wide-ranging roots exude a toxin that stunts the growth of surrounding flora, and it can grow big enough to destroy your house’s foundation in just a few years.
If your foundation survives, the rest of your house still might not: The tree of heaven’s rapid growth makes it structurally weak, and they’re notorious for dropping huge branches onto whatever lies below. And they are indeed smelly, like peanut butter that’s been in the trunk of a car for two years.
The tree of heaven isn’t on the list of species that property owners MUST remove, so if you have one, you can leave it and take your chances. If you do want it gone, though, be careful—cutting it down will only send its roots into reproductive overdrive, with dozens of Hydra-like “suckers” sprouting into brand-new trees as far as 50 feet from the original trunk. Lather, rinse, repeat.
The only thing that will kill a tree of heaven is treatment with conventional herbicides. It’s easy to imagine that being a problem in chemical-hating Portland, which is unfortunate because August, when the trees are moving food from their leaves to their roots, is the ideal time to take them out.
It’s really not as toxic as it sounds. You just slit the bark and squirt a little triclopyr, say, into the incision—more like a lethal injection than gas warfare. But who am I kidding? If the Rose City were being invaded by the aliens from Signs and the only thing that could destroy them was an amalgam of fluoride, MSG and gluten, two-thirds of the populace would just lie back and wait to be probed. All hail our new arboreal overlords!
Questions? Send them to dr.know@wweek.com.
