The so-called sentinel gardens spanned three continents and four countries, including Sweden, China, Italy and the United States. New Hampshire is home to one of two sentinel gardens in the United States. The other is located at Waterman Farm on the Ohio State University campus in Columbus, Ohio.
Researchers involved in the project hoped to make new discoveries about which insects and pathogens damage different plants.
Isabel Munck, a U.S. Forest Service plant pathologist based in Durham, NH, was among them.
“One of the biggest, if not the biggest, threats to our forests in this part of the world are invaders, like pathogens and insects,” Munck said.
If researchers noticed that a tree was having problems, they could investigate which pathogens or pests were likely to blame.
Foreign invaders can travel to the United States on wood products, packaging materials, or live plants imported from nurseries, for example. But native plants have not developed any resistance to those insects or diseases, meaning they can be especially harmful or even lethal.
Some of the trees planted at the New Hampshire Sentinel Garden in Portsmouth, NH, when they were younger. Isabel Munck
Munck said she was especially interested in learning more about fungi, which make up the majority of forest pathogens.
“The goal of this project is to try to detect them before they spread,” Munck said. He compared trees planted abroad to a canary in a coal mine, able to alert people to a problem before it becomes lethal.
He worked in one of the sentinel gardens, located at the Urban Forestry Center in Portsmouth, NH, where plants from China and Europe were grown.
Gardeners in Italy, Sweden, and China reciprocated by growing New Hampshire plants in those three countries to see how they would respond to pathogens located in those countries.
According to Munck, researchers in China found several new pathogens affecting red maple that have never been reported before.
These observations could be used to inform policy decisions on monitoring and preventing harmful pathogens from entering the country to protect forests.
“We are not going to stop international trade and the movement of goods, services and people. “It’s an attempt not to be surprised by things that have surprised us in the past,” said Pierluigi Bonello, a professor of plant pathology at Ohio State University. Bonello also led the sentinel garden research project.
“This is just step zero, not even the first step, just to see what’s out there,” he said. “Once you know there is a potential threat, in theory, you can alert border inspection facilities in the United States, for example, to be on the lookout for that specific agency.”
When invasive species go unnoticed, they can create big problems.
Beech leaf disease is one of the main concerns Munck sees in the region today, caused by nematodes, or microscopic worms, believed to come from the Pacific Rim. First detected in the US in 2012, it prevents beech trees from developing buds, so the trees stop producing new leaves. So far it has been found in 13 states, including New Hampshire, Massachusetts, Connecticut, Rhode Island and Maine.
Scientists are concerned about the rate of spread and the fact that the invasive plant could kill trees just a few years after the first symptoms appear.
Munck is also studying trees at Harvard University’s Arnold Arboretum to see what types of fungi are already present here. The 281-acre arboretum features more than 16,000 trees, including species from around the world. Some of the same species growing in the arboretum were planted in sentinel gardens around the world, so Munck can compare the mushrooms present in Boston with those in the Jiangsu province of China, for example.
“We’re trying to exclude things that are always present from things that cause disease,” Munck said.
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