KINGSTON, N.Y. — A major infestation of the destructive emerald ash borer in New York’s Hudson Valley is the farthest east discovered so far in the United States, and forestry experts are trying to map its extent as they worry about the threat to New England’s forests and streetscapes
Foresters have been searching a 225-square-mile area near Kingston for any sign of the invasive Asian beetle since February and expect to wrap up this month, the U.S. Department of Agriculture Forest Service said Thursday.
Nathan Siegert, a Forest Service entomologist leading the survey, said the initial goal will be to disrupt and slow the insects’ spread.
“I don’t think there’s much hope it can be obliterated,” he said, but there are a variety of proven countermeasures, with others being researched. He also said the Hudson may be at least a temporary barrier as the borers consume ash along the western shore.
The infestation found in July is about 25 miles from the Connecticut line, much closer than the leading edge of the main population spreading from the southern Great Lakes region, including about 150 miles away in western New York. That population has been spreading gradually at a pace of about 2 to 3 miles a year, but “satellite” colonies have leapfrogged ahead, mostly by hitchhiking in loads of logs or firewood.
The ash has been a staple of hardwood mills and is widely used in urban plantings. The borer can kill a healthy tree in just three or four years.
The state Department of Environmental Conservation and about a dozen state and federal agencies have sent teams to examine trees in the area. Foresters think the first insects arrived there as long as five to seven years ago, possibly before federal and state authorities started enforcing quarantines on the movement of ash wood.
The insect first was confirmed in western New York in 2009. The state had restricted the movement of all ash tree material from nursery stock to wood chips as early as 2007 after the borer was found in Pennsylvania. For years, the state has limited movement of camp wood to within 50 miles of where it’s cut to combat a number of forest pests. The DEC has recommended buying packaged bundles of wood that have been kiln dried, which kills the insects.
So far, infestations have been found in Cattaraugus, Steuben, Livingston, Monroe, Genesee, Greene and Ulster counties, according to a January 2011 DEC report.
Siegert said a number of steps can be taken once the extent of the eastern New York infestation is known.
“We can target removal of the largest ash trees in the infested area, as larger trees produce more adult beetles. Insecticide treatment may be an option for high-value ash trees in urban areas,” he said, adding that biological controls are also possible.
He said researchers in Michigan are working with three types of wasps that may be predators of the borer and trees can be intentionally weakened to attract the beetles and then removed.
But there’s no method now for widespread destruction of the pest.
“For the most part, it’s getting the message out about moving infested wood,” he said.
The borer, which is native to China and probably arrived in the U.S. in wood used for packing crates, was first found near Detroit in 2002. It has killed tens of millions of trees in 15 states and two Canadian provinces.
Siegert said the bugs will typically fly short distances if ash trees are available, taking longer trips only if they can’t find food. He said they are capable of flying across the Hudson River but may not be motivated to at this point.
The DEC has asked anyone who believes they have an affected tree to contact the agency. It says the adult borers are about 3/8 to 5/8 inch long, with metallic green wing covers and a coppery red or purple abdomen. They are most common in June and July but can be spotted from late May through early September. Signs of infection include the canopy dying back, yellowing and browning of leaves.