NEW FUNGUS DISEASE OF SYCAMORE 137
The tree was quite dead and the bark had fallen off, but what
attracted my attention was that the wood was entirely covered
by a thick black deposit looking very much like soot. On
examination under the microscope this ''soot" proved to be
composed of fungus spores.
I was greatly interested because I knew of no fungus which
produced spores in such abundance nor of any recorded disease
of the Sycamore with such symptoms. I searched much literature
and made a few tentative enquiries, but without success, and
finally dropped my investigations hoping that time would provide
a key to the mystery. However, after two years the fungus still
remains undetermined, and I regret to say that, instead of being
a harmless saprophyte as I first imagined, it now appears to be
a very aggressive parasite. It has spread with such alarming
rapidity that a recent count revealed about 40 Sycamore trees
which are dead or dying as a result of its attacks.
The symptoms shown by the diseased trees are so remarkable
that they cannot be confounded with anything else. The fungus
appears to invade the bark and cambium and when it has
established itself the bark begins to drop off, leaving the wood
encrusted with a thick layer of spores. These spores are produced
in such prodigious numbers that pounds could be scraped off a
single tree and the vegetation around is blackened by their dis-
persion. The fungus is insidious in its attack, and an affected
tree shows no outward sign of the disease until the bark begins
to drop off exposing the spore bed beneath ; it is apparently
then too late to save the tree.
As to the origin of the disease, I can at present only surmise
that it may be a foreign importation which has found the
conditions in Wanstead Park very much to its liking and has
flourished accordingly. In this connection it may be of interest
to note that the Endothia blight of the Chestnut (Castanea
dentata), which is rapidly exterminating that tree in the U.S.A.,
was an importation from Japan which was comparatively harm-
less in its own country, but became a destructive pest when it
reached the U.S.A. It was first noticed in a New York park
in 1904.
I have drawn the attention of the responsible authorities to
my discovery, and they agree with me that there seems to be no
previous record of such a disease in the Sycamore. They also
agree as to its serious nature. Mr. Peace, the pathologist of the
Forestry Commission, has been to the infected area and has
shown great interest. Dr. Gregory is also working on the
subject at Rothamsted; so I hope to have more definite information
to communicate in due course.
There seems to be no reason why the activities of this parasite