Many homeowners spend a lot of time and money on planting trees. The hope is that the trees will grow and last a long time.
But many trees that come from nurseries across the country are clones – they are all genetically the same – and it could be a problem.
“If you have something that’s all genetically the same and a disease or pest comes through that’s attacking them, they have no resistance,” said Cynthia Morton, a botanist at Carnegie Museum of Natural History in Pittsburgh.
Using genetic testing, Morton and a colleague found that many cloned trees come from a limited stock of parental trees from the West Coast.
“They’re taking cuttings of one tree and they’re reproducing it over and over again,” Morton explained.
To find out a tree’s genetic makeup, the scientists grind up a leaf in a lab and extract its DNA for testing, and then they look for DNA patterns within different tree samples.
The researchers found that “all the nurseries came out to [have] a very low genetic diversity,” said Morton.
Older trees with more variety may be more resilient because they have survived through pollution, pests and bad weather. These time-tested trees are often more genetically diverse as well and have a better chance of a long, healthy life.
Morton suggests asking a nursery where the trees came from before buying and look for a good variety of trees. “When we plant those plants we’re expect we’re getting something that’s going to last for 50 to 100 years,” said Morton.
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