The race is on to stop an alien invader before it can destroy the ash tree
BATTLING THE KILLER BEETLE
The race is on to stop an alien invader before it can destroy the ash tree
THERE’S A RESIDENTIAL neighbourhood in Windsor’s west end that’s a pleasant collection of middle-class bungalows and 1½storey A-frames built soon after the Second World War. There, a short walk from the Ambassador Bridge linking the southwestern Ontario city to Detroit, some three dozen 40-year-old ash trees line California Avenue —but they won’t for much longer. City forester Bill Roesel surveys the devastation caused by a voracious Asian beetle that is choking his ash trees to death. The emerald ash borer, discovered just this year in Michigan and, two months later, in Windsor, is munching mercilessly through Windsor’s 6,000 ashes, and may already have spread east and west. An immediate concern: whether it will reach Point Pelee National Park, a spectacular sanctuary for migrating birds poking into Lake Erie just 50 km to the southeast. Roesel is not looking forward to the task ahead on California Avenue. “These two blocks,”
he says, “are basically going to be clear-cut.” The devastation almost certainly won’t stop there. A federally imposed quarantine forbids the shipment of ash firewood, wood or trees from Windsor and four surrounding municipalities where the borer has so far been located. Authorities charged with stopping the invasion are considering felling every ash in a five-kilometre strip around the quarantine zone in a bid to contain the
damage. In any case, unless someone finds answers quickly, Roesel expects to lose all the city’s ashes. Cutting them down could cost up to $4 million, plus fees for safe disposal; replacing them with other species would run another $2 million.
If the defence strategies don’t work, the experts warn it could get as bad as the dutch elm disease that decimated those stately trees across North America. British Columbians know the feeling. There, the forest industry is battling a home-grown killer, the mountain pine beetle, that threatens $4.2-billion worth of timber. Ottawa has stepped in with $40 million to combat that outbreak.
With no natural predators, and thriving on trees with no effective resistance, the emerald ash borer has been free to spread. If it isn’t stopped, the biggest impact will likely be felt in urban landscapes in Eastern Canada, where the trees are widely used to line streets, and to a lesser extent on the
Prairies, where ash is sometimes used as a windbreak. But ash is not just an urban shade tree. Harvested primarily in Ontario and Quebec, it is used for furniture, flooring, kitchen cabinets, tool handles, baseball bats and hockey sticks—all of which, thanks to the iridescent green borer, may soon cost more. Ken Marchant, a forestry specialist with the Canadian Food Inspection Agency (CFIA), responsible for preventing pests from spreading, says Windsor’s infestation presents a serious threat in Ontario, and potentially other parts of Canada. Marchant says the damage goes beyond money. “It’s very dangerous to put a commercial value on any tree,” he says. “The environmental impact could be far worse.”
Native to Mongolia, China, eastern Russia, Korea, Japan and Taiwan, the borer was first spotted last May in Michigan. It took until July, with the help of a Slovakian entomologist, to identify the mysterious invader. Ten days later, Michigan clamped a quarantine on Detroit and five surrounding counties. The ash borer probably landed in Detroit’s port after hitching a ride on wooden packing crates or the scrap lumber used as wedges to secure cargo in a ship’s hold. It appears the infestation took root in southeastern Michigan at least five years ago. The state surveyed 650,000 landscape trees and 11 million ashes in forests and found half of them dead, dying or showing symptoms. Every ash trees in the affected counties could be dead in as little as three years. There are 700 million ashes in the state—for now. That’s just four per cent of the forest, but it’s still a lot of trees.
The borer kills by laying tiny eggs on the bark. Once the larvae hatch, they burrow through and attack the tree’s circulatory system just below the bark’s surface, staunching the flow of nutrients and water. A tree can be mortally infested and show no immediate outward signs. Tearing away the bark reveals serpentine grooves left by the well-fed larvae, which hibernate over the winter. In the spring, the larvae pupate and in May emerge as adults, leaving behind telltale D-shaped holes in the tree bark. Within a year, up to half of the tree’s canopy dies. The tree sometimes sprouts branches along the trunk in a last-ditch but ultimately futile effort to survive. Trees usually die within two to three years.
The Detroit River only delayed the beetle’s assault on Canada. Experts estimate the
invasion started about a year after the bug reached Michigan. Canadian scientists first spotted the bug in July, identified it in August, and followed that with a risk assessment. Federal Agriculture Minister Lyle Vanclief signed the quarantine order in mid-September. While Marchant says the food inspection agency advised local news outlets and stakeholders of the order in September, it wasn’t until a month later that the agency issued a media release to stimulate wider awareness. Lawyer Robert Holland, a member of the Windsor-based Ash Rescue Coalition, thinks authorities are reacting too slowly. Holland wants federal funds allocated promptly “so the money’s there to stop this thing next spring.”
The global free trade in bugs like the ash beede has hit nursery operators hard. Vic Bellaire, 47, owns a garden centre in the town of Tecumseh, next to Windsor, and inside the quarantined area. Bellaire says he has about 1,000 ashes, 10 to 12 years old, that would have been worth as much as $150,000. Now, he couldn’t give them away. The father
One possible strategy would be to fell every ash tree in a five-kilometre-wide ring surrounding the affected areas
of three remains remarkably optimistic— you have to be to run a business, he says. With a chill wind driving the day’s drizzle, he surveys the worthless fruits of his labour. He is prepared to move on, but wants federal officials to act promptly to stop the borer’s advance. “They have to do the right thing,” says Bellaire, “and they have to do it quick.”
But what can you do when the available research is inconclusive even on how far this bug can fly? The five-kilometre “firebreak” is one potential option, but is that wide enough? “That’s based on what we know about this beetle,” says Marchant, “which isn’t a lot.” Aiding the agency, however, are the vast tracts of almost treeless farmland in the region. Meanwhile, the CFIA has warned all Ontario municipalities to be on the lookout. Canadian and U.S. officials are collaborating, and the CFIA is trying to develop better survey techniques to more accurately define the outer limits of the infestation.
Will that be enough? In Toronto, 370 km to the northeast, city forester Richard Ubbens is taking steps to educate staff and the public to protect the 27,000 ash trees that line city streets. An infestation could cost millions, and rob entire neighbourhoods of their treasured canopy. It’s not just aesthetics, either. Without shade, increased air-conditioner use would require more electricity, exacerbating an already serious smog problem as power plants chug to keep up. Homeowners on denuded streets could see property values drop. “When you consider the whole range,” says Ubbens, “it’s quite depressing.”
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