8 More Degrees….

January 29, 2014

Canadian Hemlock (13)

The recent polar vortex has brought some of the coldest air to our region in over a decade, but unfortunately it wasn’t quite cold enough for us here at Mount Auburn.  Our Eastern Hemlock (Tsuga canadensis) trees are being killed by an invasive pest called the Hemlock Wooly Adelgid which is found throughout the Northeast and can kill a hemlock in as quickly as four years after infestation.  Populations of the insect are greatly reduced when the temperature reaches -4°F  (-20°C).   Records from our greenhouse weather station show that we’ve reached a low temperature of only 4° on the early morning of January 4th – not enough to make a dent in the adelgid population.   In the meantime, our arboriculture crew will continue to treat our remaining hemlocks and we’ll keep searching for resistant replacement trees like the 7 Chinese Hemlocks (Tsuga chinensis) we have growing at our propagation range.


About the Author: Stephen Jackson

Plant Records Manager

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