2018-08-02 / News

Invasive beetle found in neighboring county is a threat to ash trees


The photo illustrates the size of the emerald ash borer, which is smaller than a penny, and the D-shape holes it makes in bark. The photo illustrates the size of the emerald ash borer, which is smaller than a penny, and the D-shape holes it makes in bark. For the first time in state history, Rhode Island has joined a federal quarantine to slow the spread of the emerald ash borer, an alien invader that has been identified in Washington County.

Although the species has not been found in town, Elaine Peterson, chairwoman of the tree committee, said “this pest will likely become a problem moving forward.”

Recognizing this is a potential issue, she said her panel will proactively work with tree warden Steve Saracino to protect ash trees.

The state Department of Environmental Management reported last week the destructive beetle was found at an undisclosed location in southern Rhode Island. With traps still set across the Ocean State, federal and state environmental officials said it is highly likely there will be more positive identifications in the future.

The emerald ash borer accidentally arrived in North America via wooden packing material exported from China, first detected in Detroit in 2002. The invasive pest overwinters as larva under the bark of ash trees. As they grow, larvae feed and zigzag through tree tissue, leaving S-shaped tunnels that block the tree’s ability to transport water and nutrients. Once infested, ash trees rapidly decline and are killed within five years.

In Asia, the species has co-evolved with native ash trees, so there are natural enemies and pathogens that keep their levels in check. That is not the case in North America, however, where there is no solution.

The beetle has been detected in 35 states and in three Canadian provinces. Since its discovery, the pest has killed tens of millions of ash trees.

Although ash trees constitute less than 3 percent of Rhode Island forests, ash widely has been planted in urban areas as landscape and shade trees on streets, campuses, lawns and parks. A compromised ash tree may represent a potential safety risk because these weakened trees typically are found in public space, although the beetle does not directly pose any human health threat.

The adult emerald ash borer can fly only short distances, but people have accelerated their spread by moving infested material, particularly firewood. Larvae easily are transported in firewood, logs and nursery stock because they are hard to detect under the bark. Residents and visitors are reminded to protect Rhode Island’s forests by buying and burning local firewood. Wood dealers, loggers and arborists should check restrictions before transporting ash across state borders.

According to the Rhode Island Tree Council, prominent symptoms on a tree that could indicate beetle presence include long, slender shoots sprouting along the trunk, bark splitting, D-shaped exit holes in the trunk, S-shaped galleries under the bark and woodpecker activity.

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