April 24, 2014GROSSE POINTE SHORES — The tree canopy is destined to thin on North and South Edgewood.
A fungus, armillaria root rot, is attacking locust trees lining both streets as though sentries, yet are being infiltrated at the foundation.
"It's a soil-born pathogen that attacks the root system, usually through an open wound, like a gash from a lawn mower or weed whacker," said Brett Marshall, chairman of the Grosse Pointe Shores tree board and owner of a tree service company.
There's no remedy.
"Fungus enters the tree," Marshall said. "Rot and decay begins, leading eventually to decline and failure — time to remove it."
"Control has been attempted via root excavation, trenching and fumigation with little to no effect," according to a summary by the Michigan State University Extension Service.
City property lining both roads was landscaped years ago with a uniform scheme of locus trees.
Some 89 specimens remain with diameters the size of car tires.
Upon leafing out in spring, they produce a shady neighborhood dappled with sun.
Three of the trees show clear signs of disease.
"At the base, you'll see mushrooms, conks, decay and rot," Marshall said. "Next will be decline, failure and quick removal if the tree doesn't blow over by itself."
He doesn't anticipate allowing the problem to get that far.
"We're not going to lose them all any time soon," he said. "They're still sound and solid at the base, but this is something the city council needs to be aware of."
It will cost at least $300 per tree to cut them down, Marshall said.
"Depending on how the tree board and council wants to work, we could systematically take down three or four per year," he said. "The Grosse Pointe Shores Improvement Foundation replants."
There are 2,800 to 3,000 trees on city property in the Shores.
That includes less than 30 ash trees out of 330 before invasive emerald ash borers began wiping them out 10 years ago.
Ash loss included every tree on city property lining Hawthorne.
Marshall seeks to diversify the municipal tree population.
By planting a variety of trees, the urban forest is insulated from dramatic loss when a pest targets a monoculture.
A noted example is Dutch elm disease virtually wiping out once-ubiquitous American elms.
"We will continue to plant more diverse trees throughout the Shores," Marshall said. "That's been the tree board's goal, to continue to plant diversity, so we don't have this problem again."