Saving the American Chestnut Tree

By Keith Chasteen, The American Chestnut Foundation (TACF) Louisville Branch

The Louisville Zoo continues to partner with The American Chestnut Foundation (TACF) through the Louisville Branch of the Kentucky Chapter. This partnership began in 2008 when five American chestnut seedlings were planted at the Zoo to test the suitability for growing chestnut trees in the area. As of 2013, two of the original five trees are still growing and showing signs of flowering.

The growth of the American chestnut trees at the Zoo is significant to keeping the tree from becoming extinct. Beginning in 1904, an imported fungus called “chestnut blight” killed chestnut trees throughout their native range (from Maine to Mississippi in the Eastern U.S). Due to the soils and many historically wet areas within the lower areas of Jefferson County, American chestnut trees were most likely rare within the city even prior to the blight, but common in the Knobs.

The American Chestnut Foundation has a breeding program where blight resistant genes are bred into the American chestnut trees with the hope of eventually having resistant trees that will be able to be transplanted in locations where they will freely produce new trees with strong resistance.

American chestnut trees can still be found throughout their natural range, but typically these trees exist as sprouts coming from the remaining root systems of trees that were killed by the blight. Chestnut blight will kill the above-ground tree, but does not kill the root system. Often, these stump sprouts will grow for 8 to 10 years before being killed back once again by the blight. Often, they will get large enough to flower and reproduce.

On March 30, 2013, the Louisville Branch of TACF, planted five potentially blight resistant American chestnut trees near the Zoo’s Butterfly Garden. The trees are protected with a wire cage to prevent deer damage during the first several years of growth. Once the trees become tall enough to survive browsing by deer and large enough to withstand rubbing, the wire cages will be removed.

The American chestnut trees at the Louisville Zoo are being maintained by TACF volunteers along with the Zoo’s Horticulture staff. Learn more about TACF at