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Researchers identify new threats to American chestnut trees

Emily Dobley, a graduate student studying at the Lake Erie Regional Grape Research Expansion Center, has identified a new fungal threat to American chestnut trees.Credits: Pennsylvania State University

American chestnuts were almost perfect wood for lumber companies. It was tall, straight, non-perishable and fragile. It was also prolific and sent a new shoot that grew rapidly.


In the early 1900s, this species occupied a significant portion of the eastern hardwood forest. There are nearly 4 billion American chestnut trees in the United States, each growing up to 100 feet and having a trunk thickness of 4-7 feet. Healthy trees lived 400 to 600 years and produced several bushel nuts each year.

But today, finding healthy chestnuts can be difficult. Tree fungal pathogens imported from Japan and China have wiped out seeds within 40 years. The loss is believed to be the largest ecological disaster in history that has hit the world’s forests.

“Because the pathogens are endemic to Chinese and Japanese chestnuts, the two have co-evolved,” said Emily Dobley of Penn State University, who graduated from Penn State University’s Master’s degree in Plant Science and Gardening. She is conducting research at the University’s Lake Erie Regional Grape Research Expansion Center (LERGREC) in the northeast. “But American chestnuts have never been exposed, so there was little natural resistance. Think of it as smallpox in wood.”

Today, there are less than 1,000 American chestnut trees, located in isolated areas outside the historic range of trees throughout New England, primarily along the ridges of the Appalachian Mountains, in the eastern half of the United States.

Some can be found at LERGREC. There, researchers have been testing 15 chestnut trees since 2013. Five each of the American, Chinese, American and Chinese hybrids developed by scientists are planted in one long row.

Brian Hed, a plant pathologist at LERGREC, said:

“Most trees suffered from wilting due to disease, insects or weather and had to be cut down and renewed,” he said. “Hybrid trees are a notable exception. Three of them are currently 17 to 21 feet high.”

The tree is updated using sucker growth from the original rootstock.

“American chestnuts are now designated as” functionally extinct. ” That is, the species technically survives, but cannot reproduce. The shoots rarely grow large enough to produce nuts, which is a future generation. “

Perhaps the most promising hope for American chestnuts today is the development of transgenic and genetically modified trees. Scientists are trying to design trees as close as possible to American chestnuts, using enough of the genetic material of chestnuts to resist blight.

“Researchers have developed a partially dead-resistant transgenic American chestnut that can withstand infection from dead-causing pathogens,” Dobri said. “It doesn’t kill the pathogen; it still exists, but it doesn’t destroy the tree.”

When scientists try to reintroduce American chestnuts, the current species balance in US forests can cause another problem. Oak trees are rising to fill the place.

“It will be a challenge for American chestnuts to re-establish themselves in forest ecosystems,” Dobri said.

American chestnuts can cause other problems in the forest. In 2018, while working as an undergraduate researcher at LERGREC, Dobri discovered a fungus that was not typical of American chestnut species.

“Initially, I assumed this was an abnormal symptom of chestnut blight infection, but when I took a sample and investigated it, I couldn’t find it. Blight, But a pathogen commonly known as chestnut brown rot. At that time, no reports of this fungus had been published in our hemisphere. “

Dobri continues to study domestically isolated strains to see if they are harmful to tree species closely related to chestnuts, such as oak.

“If this is the case fungus Prove that orcs are pathogenic, which can be another blow Woods Dynamics, “she said. “That’s why chestnut projects and other projects are so important to protect the diversity and future of our forests.”


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Quote: Researchers have obtained American chestnut trees from https://phys.org/news/2021-10-threat-american-chestnut-trees.html on October 25, 2021 (October 25, 2021). ) Identified a new threat to

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Researchers identify new threats to American chestnut trees

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