25 
and, if of a retentive character, properly worked before replanting. 
All unsound portions of the root must be cut away, and all traces of 
decay removed; in cloudy weather the roots may be lefi partially 
exposed for a few days; afterwards covered with leaf-mould or with 
light alluvial soil. The decayed bark must be pared away in such a 
manner as not to wound the sound portion more than can be avoided. 
Frequent application of tar-water to the root and stem will be found 
beneficial in all except extreme cases. A light top-dressing of lime 
mixed with a little sulphur would probably prove of benefit. 
This disease is most frequent among trees growing in cold sub- 
soils; it is rare on open volcanic soils or where the trees have been 
surface-planted. It attacks the lemon and citron more frequently 
than the orange, and its effects upon the former are more severe than 
upon the latter. The shaddock appears to be exempt from its attack, 
but the lime sometimes suffers severely. 
In some cases a gummy secretion is exuded by the affected parts 
of the stem during the earlier stage of the disease, and ceasing with 
the decay of the bark; this constitutes the disease termed “ lagrima,’’ 
but I am unable to draw a distinction between the two. 
ROOT-FUNGUS. 
See ante, page 10. 
BLACK BLIGHT, OR LEMON SMUT (Capnodium australe, n. sp.). 
TI have no hesitation in referring this fungus to Capnodiwm, but 
am unable to identify it with any species of which I possess descrip- 
tions ; itis therefore provisionaliy distinguished as Capnodium australe 
for convenience of reference. 
The fungus forms a black film on the surface of the leaves and 
twigs, and usually develops short, erect, excessively-branched filaments 
from one-tenth to one-quarter of an inch in length, sometimes in such 
abundance as to form a velvety surface, but the general appearance of 
trees clothed with this sooty-coloured parasite is simply disgusting. 
The fungus acts injuriously by closing the orifices of the air- 
passages, and preventing the direct action of light, so that the leaves 
are unable to discharge their functions. 
By some cultivators it is said to be the excreta of the large white 
scale (Icerya purchasi); it is, however, a true fungus, although 
frequently found growing on trees infected by scale, aphis, or other 
homopterous insects. It certainly assumes its most luxuriant growth 
on twigs or leaves coated with the boney-dew secreted by many of 
these insects, but, so far as my observation serves, the connection is 
not invariable. 
Trees infested with scale and aphides are not always infested with 
the fungus; and trees affected by the fungus are not invariably 
attacked by Homoptera. ; 
That it has no necessary vonnection with Icerya is apparent from 
the fact that orange and lemon-trees were observed to be infested with 
the parasite at least ten or twelve years before the introduction of 
Icerya into the colony. 
