We're forewarned once again
Jul. 31—"Forewarned is forearmed" may be a sensible and common saying, but we're frequently dismissive of forewarnings.
A reminder of that came from a reader who sent me a copy of a Nov. 10, 1988, article by Free Press columnist Don Gordon.
His warning of the dangers of a monoculture of ash trees has been borne out nearly 35 years later.
Gordon, a longtime professor of botany at Minnesota State University, wrote a popular weekly column, often answering readers' questions about landscaping, gardening and pest problems.
While the rural North Mankatoan had a massive garden and plenty of gardening expertise, Gordon was quick to point out that he didn't write a gardening column.
"It was a horticulture and environmental column. I don't know whether I always succeeded, but my goal was always to advocate minimal environmental destruction," he wrote in his farewell column in 2012, after 36 years of imparting advice to Free Press readers.
His 1988 column noted the "tragedy" of the American elm, a tree that was ubiquitous along boulevards in many cities in the county. The trees were decimated in the 1970s by Dutch elm disease. So many elms were originally planted because they were cheap to produce, easy to grow, towering beauties.
When the elms died, the go-to tree for cities and homeowners quickly became the green ash, which became the most commonly planted tree.
Gordon wrote that the overuse of a single type of tree was destined to repeat the devastation of Dutch elm disease. The ash, he noted, was prone to all sorts of pest problems including leaf rust, cankers, leaf spots and aphids. Also, he noted, ash borers were a problem.
He wasn't talking about the granddaddy of destructive borers we're dealing with now — the emerald ash borer. That wasn't first discovered in the U.S. until 2002.
But there were plenty of mostly native ash borers such as the clearwing, redheaded and banded ash borers.
The emerald ash borer is the most destructive invasive forest pest Minnesota has ever encountered, destined to kill off the estimated 1 billion ash trees in the state. In many cities ash trees make up 60% of the trees.
Many argue local, state and federal governments aren't yet providing enough funding and resources to remove ash, particularly on boulevards and in parks, and quickly replace them with new trees.
State Rep. Rick Hansen wrote that Minnesota spent what would today equate to $290 million on Dutch elm disease. So far — even though about seven times more ash exist in Minnesota than there were elm — the state has funded only $18 million for emerald ash borer.
More will need to be allocated as the number of dying and dead ash grows. They not only need to be removed but to be quickly replaced with new trees.
If warnings from decades ago were then heeded, we could have avoided much of the monoculture of ash trees we have today.
A hopeful sign is that cities are taking the warning about planting too many of one kind of tree. They are replacing the ash with a variety of trees like ginkgo, swamp white oak, hackberry, locust, linden, catalpa and, yes, even elm that have been bred to be more disease resistant.
They will take decades to mature, but the diversity should prevent the kind of crisis we are facing now.
Tim Krohn can be contacted at tkrohn@mankatofreepress.com or 507-720-1300.
