264 
but more or less rounded. The spots are irregularly scattered over the 
leaf, but usually more near the edge than elsewhere and they frequently 
run into each other. 
The leaf is often attacked when just opened and before it has 
attained its full green colouring. Indeed I am inclined to think that 
the attack commonly commences in the bud. After a time the centre 
of the spot becomes hard and black and the oil glands swollen and 
protuberant. At length on the under, more rarely the upper, surface of 
the leaf from the blackened spot can be seen with a lens fine white 
hairs like a mildew. 
On examination with the microscope these are seen to be fine fila- 
ments (Sporophores) bearing at the apex a number 3 to 9 short arms 
all nearly equal. At the apex of each, at first abruptly decurved then 
spreading, is a yellow sporangirum which doubtless produces one or more 
spores which drifted about by the wind attack other parts of the plant. 
The life history of this x>lant has not yet been worked out but it 
appears to be one of the Peronosporeae. In any case it is a most injuri- 
ous pest, destroying the leaves as soon or before they emerge from the 
bud stage. 
Indeed I have seen a tree of about 12 or 14 feet tall quite killed 
by the attacks of this fungus. Every bud as it appeared was destroy- 
ed, and when the terminal bud of a branch was gone and the lateral 
buds extruded they were killed in like manner. 
It is I believe also this fungus which kills the seedlings in great 
quantities by destroying the bud. 
Some trees in the Botanic Gardens were badly affected by this 
fungus and the treatment of washing them with Bordeaux mixture was 
tried with marked success. The mixture was syringed on to the trees 
with a bamboo squirt till the foliage was very conspicuously blue. At 
the next putting forth of leaves it was noticed that the young leaves 
which came out were not attacked by the fungus while the trees that 
were not syringed were as bad as before, the leaves being all spotted 
with the fungus and many buds blackened and dead. 
The worst attacked trees are those on bad stiff yellow clay soil 
exposed to full sun. 
A tree growing close under a large para rubber tree was but little 
damaged though the fungus was present. This tree however appears 
to be overshaded as though quite an old tree, it has as far as I have 
known never flowered. The soil it grows in is better and richer than 
that in which a tree about 50 yards away is growing and which is in a 
bad state from the attacks of this fungus. There can be no doubt that 
the best treatment for this pest is the destruction of its spores by the 
aid of the Bordeaux mixture of copper sulphate and lime with which 
the trees should be well sprayed. As the spores of the fungus are 
chiefly produced on the lower side of the leaf, the tree should be spray- 
ed from below upwards. Infected leaves on the ground should be 
sprayed and swept away and burnt and the trees well manured. 
Seedlings which are often killod apparently by this fungus should 
be carefully sprayed with a weak solution of the Bordeaux mixture and 
should be grown at a distance from the infected trees. 
H. N. Ridley. 
