The emerald ash borer (EAB) is now officially attacking ash trees in Baltimore, one of 25 states afflicted since the exotic pest was discovered in Michigan in 2002. While this eco-crisis has already wiped out tens of millions of ash trees, you do not have to lose your large and beloved ash tree(s), advised top national EAB expert Prof. Deborah McCullough of Michigan State University during a workshop and lecture at Cylburn Arboretum in late March.
In 2010, the new highly effective chemical treatment of Emamectin benzoate (sold as TREE-age) became a serious "game changer," she said, allowing cities and homeowners to economically save specimen ash trees. "I use it on the three ash trees I have in my front yard. It's good for two to three years, and I have the beauty and benefits from those trees. When you factor in the cost of taking down those trees, the treatments really make sense." TREE-age must be applied by licensed or certified pesticide applicators.
Emerald Ash Borer was found in our city in June 2014 in special beetle traps in Druid Hill Park and near Fort McHenry. Since then, USDA inspection teams have located a few infested trees. City Forestry and TreeBaltimore have not been planting ashes for some years now, but the ash is the one of the most common trees in Baltimore - 214,000 trees, 8.6 % of trees total population.
In coming years, these shiny green beetles will be a death sentence for many of Baltimore's ash trees, which make up a tenth of our urban forest. Erik Dihle, Chief City Arborist, has indicated that the city will use injections to save as many as 2,000 of the city's 4,000 ash that grow on streets and in parks.
Baltimore is following the actions of some Mid-western cities which are saving their prime ash trees through pesticide injections, finding it to be far more cost effective to save the mature ash trees in all their glory than to pay for their removal. Even if a tree is looking sickly--with as much as a third of its canopy gone – it is still a candidate for treatment and can bounce back once the beetles are killed.
The emerald ash borer (EAB), a shiny winged insect the size of a penny, is thought to have arrived in the United States in solid wood packing material from its native Asia. First detected in the Detroit, Michigan/Windsor, Ontario area in July 2002 and then in Ohio, infestation by EAB has has already killed millions of ash trees in the central and northeastern United States. Prof. McCullough, a forest entomologist, has been active in studying EAB since she was one of the scientists to find it near Detroit. This is the most devastating tree pest to hit the United States since Dutch elm disease.
In August of 2003, Maryland became the third state to detect EAB. That month, state inspectors found the emerald ash borer on some of 121 ash trees at a landscape nursery in Prince George's County. Despite measures to eradicate the pest, in 2008, EAB beetles showed up in Charles County. By 2011,
EAB had been detected in several more counties – Anne Arundel, Howard, Allegany, and Washington. At first, states tried to prevent EAB spreading by cutting down all nearby ash trees where EAB might breed. But now many cities have a mixed approach--cut down infested trees, but save and protect large and beautiful specimens by pesticide injections.
The good news for homeowners who have beautiful, old ash trees: “There is no reason for a landscape ash tree to die from emerald ash borer anymore,” says Deborah McCullough, a professor of entomology and forestry at Michigan State University. In 2009, Milwaukee started injecting trees with a pesticide called Tree-age.
Applying pesticides every two years costs about $250 a tree, while removal and replacement is $700 to $1,200 a tree, she said. “You can treat a tree for a lot of years before you reach the cost of removing that tree.”
“The treatment is so effective and so much cheaper than removal and replacement ," said one Milwaukee Forestry Services manager, "that I can’t get a single elected official to weigh in on the side of removing healthy trees because we don’t have to, and that is never popular with the public.” Milwaukee could not afford to lose the 28,000 prime ash trees owned by the city all at once, he said. “The injections allow us to decide what happens to those trees, not the beetle.”
Hydraulic guns drive the pesticide into the tree through shallow holes drilled in the bark. Each tree is dosed every two years. Positive results are evident: Private ash trees that were not injected are dead, while treated ash trees on city property stand nearby in good health.
It has not been proven yet, but it may be possible to spread treatments farther apart once the main wave of beetles passes, thereby reducing future costs.
More information from the state of Maryland is available at http://www.emeraldashborer.info/homeownerinfo.cfm#sthash.Kgfkvocu.dpbs