Proceedings 51 
The fungus, Fusicladinm dendriticum, which causes Apple 
Scab, is as a rule noticed by the apple-grower on the apple alone, 
since here it forms conspicuous black spots or blotches, or it may 
cause the apple to crack. But when the life-history of this fungus 
is followed out, it is found that the same fungus occurs on the 
leaves and on the young wood of the apple. It is on the leaves 
where the fungus increases so rapidly and whence it spreads to the 
apples; while it is on the young wood that the fungus lives during 
the winter months, and whence it infects the new leaves in the 
following spring. Possessed of this knowledge, the grower, by 
spraying the young wood in the winter with a winter-wash, and 
then if necessary, the young leaves directly they are unfolded 
with the summer-wash of ‘Bordeaux mixture,’ can entirely pro- 
tect his crop of apples from injury. 
With regard to the Pear-Scab, /. pirinum, the same facts 
as to life-history and preventive treatment hold good. 
The fungus which caused Cherry Leaf Scorch is called Gno- 
monia erythrostoma. Cherry trees which suffer from this disease 
gradually become unfruitful and stunted in growth, and the 
cherries develop hard blackish spots in the flesh. The leaves turn 
yellowish during early summer, and then instead of falling from 
the tree in the autumn, remain, although dead, firmly attached 
to the boughs. A Cherry orchard attacked by ‘Cherry Leaf 
Scorch’ can thus be recognised during the winter and spring at 
a glance, through the dead leaves hanging on the trees, giving 
them the appearance of trees which have been killed by fire. The 
reason for this phenomenon is that the threads of the spawn, 
(mycelium) of this fungus grows down the leaf-stalk during 
the summer months, and finally kills those cells at the base of 
the leaf-stalk which normally form the special layer of cork-cells 
which brings about the fall of the leaf. As a result the dead leaf 
remains permanently attached through all the winds and gales 
of winter, until it rots away. Now these dead leaves bear the 
fruit-conceptacles (with their contained spores) of the fungus 
Gnomonia. These fruit-conceptacles are ripe in the spring and 
then eject their spores; since the dead diseased leaves of one sea- 
son remain on the tree until the following summer, the young 
leaves as they unfold become inevitably infected year after year. 
