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Insect infestation prompts clear-cut of red pine in Bear Brook State Park

Thousands of red pine scale, which are about the size of a fleck of pepper, could be crawling on a single red pine and not be visible to the naked eye. Although their presence isn’t apparent, the damage they’ve wrought on Bear Brook State Park soon will be when about 120 acres of infested trees are removed this winter.

“This is going to be visually dramatic to the average park user and to the average person driving through on Deerfield Road here,” said Will Guinn, regional forester for the state’s Forest Management Bureau.

The infestation in Bear Brook is New Hampshire’s first case of red pine scale. The red pine scale is an insect that first appeared in 1940s in Connecticut, and spread to New York and New Jersey in the 1950s and 60s. The insects feast on red pine trees, first discoloring the needles from green to a rust red color and eventually killing the trees, which can happen as rapidly as within three to five years of the infestation. The insects cannot fly, so the most common mode of transportation is by wind or on birds or squirrels.

There is no way to combat the insects, so in order to prevent their spread to the northern part of the state, the infested trees must be removed, Guinn said. Only about 200 acres of Bear Brook’s 10,000 acres are covered in red pine trees, said Scott Rofle, the park’s forester. But those red pine stands happen to be in some of the parks most visible areas, including right along the entrance to the park on Deerfield Road and along New Rye Road and One Mile Trail.

Removing the trees will be visually jarring, but it’s the most responsible and the only effective way to stop the infestation and slow its spread, according to Guinn.

“It’s unfortunate, but it has to happen. The state has a duty to minimize the spread of this by managing its own lands,” Guinn said. “We’re trying to do the correct thing and learn from what’s happened down south and manage appropriately.”

In states such as Connecticut, red pine trees have been almost completely wiped out, Guinn said.

Guinn hopes the trees will be gone by the end of the winter, before birds begin migrating in again and potentially continuing to spread the disease. The state will put the harvesting up for public bidding in December, just as it does with any other timber harvest. By removing the trees before they are dead, the state will still make a profit off of harvesting the trees because the lumber is still usable.

The top of the trees will be chipped and burned for energy, and the trunks will be logged, Guinn said. Although many loggers may already have their winter projects set, the state is hoping for someone to take care of the project during the winter.

Foresters first noticed a change in the trees in the late spring and summer. The most obvious mark of the red pine scale is discoloration, officially called “flagging,” of the tree needles. First, the needles on lower branches will begin to turn yellow and then into a reddish color, and the discoloration will gradually move up the tree in bands. The insects will also produce flocculent, a white fuzz that is more visible. The trees will die when the entire crown has turned brown.

Several trees were then cut down, and the state consulted with the U.S. Forest Service to analyze the trees. Infestation of red pine scale was confirmed in late September, and the spread since then has been rapid, with visual discoloration on whole stands of red pine trees in the park.

“This is happening really fast, that’s why we want to get the word out,” Guinn said.

Once the red pine scale lands on the trees, it opens them up to a whole other host of bugs that can speed up the death of the trees. As the trees weaken, for example, they’re more susceptible to infestation by turpentine beetles, which burrow and lay eggs near the base of the tree. If the trees die, it makes the forest more hazardous for fires, and the state cannot make money from the logging. All of these factors combined make the foresters even more anxious to remove the trees.

“We want to mitigate any safety concerns, any fire concerns, any economic loss. And number one we want to slow the spread down throughout the state,” Guinn said. “We’re not going to say that we can stop the spread because it can keep coming up from the south through birds or whatever other sources of movement.”

It’s unclear why the insects have finally spread to New Hampshire, but one theory is that the spread is due to milder winter, because the insects have a hard time surviving the cold winters, Guinn said, although that theory has no scientific proof.

Although the removal of the trees will be a stark change to the park’s aesthetics, the foresters at Bear Brook have done active forest management in the past, including planting an understory of white pine trees. That means the landscape will not be completely barren, it will just be full of much shorter and younger trees, which can grow up to 18 inches in height per year.

Suspicions of red pine scale infestations can be reported to Kyle Lombard, Forest Health Program coordinator, at
464-3016.

(Kathleen Ronayne can be reached at 369-3309 or
kronayne@cmonitor.com or on Twitter at @kronayne.)

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