21 
Vernacular Name.— I know of none. 
Leaves and Sooty-mould. —This tree has the drawback that it is liable to 
the unsightly appearance known as sooty-mould, so-called because the leaves are 
often dusted with a black powder. Other trees liable to it in New South Wales are 
certain Eugenias, the Black Apple (described in this Part), whilst amongst exotics, 
orange, lemon, and cinnamon trees are often attacked. 
Attention is invited to a paper, founded on Australian material by D. 
M‘Alpine, entitled “ the Sooty-mould of citrus trees; a study in Polymorphism 
(Capnodium citricolum, n. sp.)”* 
Species of fungi included in the group Perisporiem are the cause of these 
black sooty coatings found on leaves frequented by green-fly {Aphis) and other leaf 
insects. These are purely epiphytic and saprophytic forms which derive nourish¬ 
ment from the “ honey-dew ” secreted by these insects. They multiply very 
rapidly, and soon form dark coatings on the upper side of the leaves and twigs. 
Little damage need be feared, since the leaves retain their green colour, and the 
coating is not enough to stop access of light. Amongst them are species of 
Capnodium, Meliola, and Apiosporium, as well as the conidial forms Fumago, 
Torula , Antennaria .f 
The sooty-mould on our Scolopia is usually Capnodium. 
In his account of “ Diseases of the Orange in Florida,” Lucien M. Under- 
woodj gives an account of the sooty-mould of the orange and olive trees in California 
and Florida. 
The honey-dew is there produced by the bark lice, and the sooty-mould is 
Capnodium citri, Berk. 
Dr. W. G. Farlow recommended treatment with a strong spray of alkali 
soap. Underwood says: “This disease has not yet made sufficient progress in 
Florida to demand such treatment, and with the natural enemies of the scale insect 
to check their development, is not likely to prove a serious difficulty.” 
Unfortunately sooty-mould is more prevalent in the Sydney Botanic Gardens 
than I like to see it, but our difficulty is that we have to grow plants of very 
different requirements under practically identical conditions. For example, 
Scolopia Broionii naturally grows in brushes, i.e., with rich, deep soil, conditions 
available in but small areas in the Botanic Gardens, where the soil is often shallow 
and poor. Many of our insect and fungus pests would disappear if the trees on 
which they grow could have more genial conditions. They would thus become full 
of vigour, and would repel bark lice and Aphis, and sooty-mould is a consequence 
of the presence of these insects. 
• Proc. Linn. Soc., N.S. IF., xxi, 469 (with Plates XXIII-XXXIV), 1896. 
t “The Diseases of Plants induced by Cryptogamic Parasites,” Von Tubeuf, translated by William G. Smith, p. 181. 
X “Journal of Mycology,” Periodical Bulletin, Vol. VII, p. 35 (1891). U.S. Dept, of Agriculture. 
