229
PRESIDENTIAL ADDRESS
Fungi and Beech
BY PROFESSOR C. T. INGOLD, D.Sc.
[Delivered 27 March, 1954]
For quite A number of years now I have had the pleasure
of joining in the autumn fungus foray of the Essex Field
Club, and much of our collecting has been in beechwoods.
So I have chosen today to review the interesting question
of fungi in all their various types of association with Fagus
sylvatica.
Some fungi* are obligate parasites, being able to grow
only on a living host. Rusts, downy mildews and powdery
mildews are some of the best-known examples. Most of
these affect the leaves or the sappy tissues of very young
shoots. On the whole, beech is remarkably free from
attack by these obligate parasites. The leaves are hardly
ever disfigured by fungi. How different are the leaves of
sycamore, regularly attacked by the tar-spot fungus
(Rhytisma acerinum) or those of oak so often whitened and
distorted by powdery mildew (Microsphaera alphitoides).
Very rarely this fungus does, however, attack beech.
I may now pass to facultative parasites which can
attack and kill living tissues of the tree but which may also
live as saprophytes on dead organic matter. These
facultative parasites can also be grown in pure culture on
sterile nutrient jelly in the laboratory. Outstanding
amongst these is the Honey Fungus (Armillaria mellea),
one of the chief scourges of forests. This abundant fungus
is quite unspecialised in its host range, attacking both
broad-leaved and coniferous trees, and even shrubs such as
gooseberry and privet. It not infrequently kills beech,
*The term "Fungi" is used in a narrow sense and excludes slime moulds
(Mycetoza) and bacteria.