There was a time, not that long ago, when American chestnut was the dominant tree species in the Carolinian zone of Ontario. In some places, 25 per cent of the trees were chestnut.
Estimates are in the period before 1920, there were 15.2 million trees in the stretch south of a line from Toronto to London to Grand Bend. Outside of Ontario, American chestnut ranged as far south as the northern border of Florida. Chestnut is an excellent wood to work with and is rot resistant. Many local barns and houses were built from it. The nuts were an important cash crop for humans and livestock a century ago.
Then a fungal blight, which first came to North America in the 1870s in Virginia, made its way into this part of Ontario. The chestnut trees died out and others filled in.
“This disease girdled the trees and got in under the bark so the trees died before they could produce nuts,” said Gordon Chinnick of the Canadian Chestnut Council.
When the last survey was completed in 2014, there were 2,531 trees. And the disease is still out there. With 2,500 trees out there, most are in isolation. “Even if they are resistant, they aren’t close enough to breed with other trees,” Chinnick explained.
The Canadian Chestnut Council is surveying the remaining trees and assessing a breeding program to breed trees resistant to the blight.
One of the council’s most recent initiatives is called Breaking Isolation. This project involves taking cuttings from the different isolated trees and making grafted trees. Some of these grafted trees are planted near isolated trees with the hope pollination will occur in a few years. This work is being led by Dr. Dragan Galic, the researcher for the council, who is based at the Simcoe Research Station.
The council has plantations in Brant and Elgin Counties for its breeding program. There are two separate breeding programs. One aims to propagate Canadian trees to keep the species and its genetics alive and the second crosses local trees with Chinese chestnut, which is resistant to the blight.
“We’re trying to backcross it so it is 97 per cent Canadian genetics before we release it back out,” Chinnick said of the Chinese hybrid program.
The gene conservation plots are separate so there is no intermixing that isn’t intentional and to protect from die off. These are strictly Canadian genetics and as many trees are being put in the program as possible to allow natural gene diversification.
The council is also involved in a DNA analysis project to check if the genes are pure in the wild trees. Property owners with a chestnut tree on their property can submit it for analysis for a small fee. Interested people can also join the council.
For more information, visit the council’s web site at https://www.canadianchestnutcouncil.ca. The council is a charitable organization and always welcomes donations.