Diatrype disciformis (Hoffm.) Fr.

Chestnut Blight Disease
Contributed by
Sandra L. Anagnostakis
Connecticut Agricultural Experiment Station
Box 1106
New Haven, CT 06504
Phone 203-974-8498
Sandra.Anagnostakis@po.state.ct.us
Figure 1. An American chestnut stem with a chestnut blight canker. (Click image for larger view and more information).
Chestnut blight, or chestnut bark disease, is caused by an introduced fungus, Cryphonectria parasitica
(Murrill) Barr, (formerly Endothia parasitica [Murrill] Anderson & Anderson). The fungus enters wounds,
grows in and under the bark (Fig. 1), and eventually kills the cambium all the way around the twig,
branch, or trunk (33). Sprouts develop from a burl-like tissue at the base of the tree called the ‘root
collar,’ which contains dormant embryos (39). Sprouts grow, become wounded and infected, and die, and
the process starts all over again.
Cankers were first reported in the United States in 1904 on American chestnut trees (Castanea dentata
[Marshall] Borkhausen) (Fig. 2) in New York City (32). None of the control attempts (chemical treatments,
clearing and burning chestnut trees around infection sites) were successful (47). By 1926 the fungus was
reported throughout the native range of American chestnut (Fig. 3), and a major forest tree had been
reduced to a multiple-stemmed shrub (17). In 1912 the Plant Quarantine Act was passed to reduce the
chances of such a catastrophe happening again (49).
Fig. 1
Fig 3
Fig. 1. An American chestnut stem with a chestnut blight canker (Castanea dentata with a
Cryphonectria parasitica canker). The fungus enters through wounds such as the broken branch
stub on the left, and grows in and under the bark, killing the cambium. Fungal stromata break
through the lenticels and pycnidia producing conidia and perithecia producing ascospores are
formed. Photo by R. A. Jaynes.
Fig. 2. An American chestnut tree (Castanea dentata [Marshall] Borkhausen) growing in Scotland,
Connecticut in 1905. The tree was 83 feet tall, 27 inches in diameter, and 103 years old.
Figure 3. The natural range of American chestnut as presented by Saucier in 1973
http://www.apsnet.org/online/feature/chestnut/top.html
Fig. 2