Sometime in the mid-to-late 1800s, a ship from England
arrived at the busy Canadian port of Halifax, N.S. On board was a consignment
of plant material, including European beech (Fagus sylvatica L.) saplings,
destined for the city’s Public Gardens. These trees prospered in this northern
city whose latitude and maritime climate were similar to those of England.
Some 30 years later, large numbers of American beech
(F.grandifolia) trees in forests around Halifax began dying of unknown cause,
and in the late 1920s, John Ehrlich, a Canadian graduate student at Harvard,
began a PhD study of the cause and consequence of the emerging problem. His
work, published in 1934, named the disease, described the causal insect/fungus
complex, and laid the groundwork for nearly everything that has been learned
since. Above is a map of
the spread of the Beech blight.
Beech bark disease is caused by the combined actions of an
insect, the beech scale (Cryptococcus fagisuga), and a fungus (Neonectria faginata).
The insect feeds on the tree creating holes in the tree bark which become an
entry point for the fungus and, by stressing the tree, decreasing its
resistance to the subsequent fungal infection. Since the 1920s, the disease has
spread a few miles each year, killing hundreds of millions of Beech trees and
ruining billions of board feet of lumber.
Perhaps by some cosmic symmetry, Nova Scotia is a refuge for a few American Chestnuts. The American chestnut (Castanea dentata) was devastated by the chestnut blight, a fungal disease. It was one of the most important forest trees throughout its range, and was considered the finest chestnut tree in the world. It is estimated that between 3 and 4 billion American chestnut trees were destroyed in the first half of the 20th century by blight after its initial discovery in 1904. Very few mature specimens of the tree exist within its historical range, although many small shoots of the former live trees remain. There are hundreds of large (2 to 5 ft. diameter) American chestnuts outside its historical range, some in areas where less virulent strains of the pathogen are more common, such as the 284 trees documented by Parker Donham in the Maritimes. Among them are:
THE ASHDALE TREE (Hants County) Planted by Clyde Dimock
when he returned from working in the USA in 1905. This tree is considered to be
the largest chestnut in Canada and one of the largest in North America.
THE UNIACKE TREES Quite possibly planted by Governor John Uniacke
when he built the estate property, prior to his death in 1830. Because this
tree grew in a competitive condition, it retained the typical straight stem of
the true chestnut.
SWAIN'S CHESTNUTS George Swain was a horticulturist at the
Canada Department of Agriculture Research Station Kentville. After a number of
years George was successful in crossing the old Bridgewater tree (now dead)
with the Ashdale tree in 1965. This pollination produced over 20 nuts which
produced fifteen seedlings. Two are currently growing in the Halifax Public Gardens, and three are growing at the Kentville Research Station. Records have
apparently been lost on the remaining seedlings.
THE BOWATER CHESTNUTS During the early 1980s, Bill Journey,
Manager of Silviculture, Bowater-Mersey, purchased 300 bare-root American
chestnut Chinese chestnut crosses)seedlings. After increasing their size in
their greenhouse, they were planted throughout South-Western NS as a public
relations project. Except in Queens and Halifax counties, only two were planted
in each county. The remainder was planted at their seed orchard at Melvern Square, Annapolis County – approximately 60 trees.
