39 
“ SCABBING ” OF LEAVES. 
I am indebted for the specimens on which this account is based 
to Mr. H. Tryon, Government Entomologist of Queensland, who 
was the first to call attention to the subject in Australia, and pub¬ 
lished a full description of a fungus associated with Leaf scab 
ten years ago in his Report on Insect and Fungus Rests. In 
Queensland the leaves of both Oranges and Lemons, including 
the petioles, have been found elYected with “scab,” and the first 
fungus found associated with it was Ramidaria scabiosa n. sp. 
In this instance the scabs were very conspicuous on older leaves, 
becoming elevated and rough, and as many as 50 have been 
counted on a single leaf. They may be equally distributed on 
both surfaces, sometimes only occurring on one, and two or more 
may run together. The usual effect upon the tree is to cause it 
to shed its leaves after becoming yellow, and consequently to 
produce poor crops or none .at all. In a vigorous tree, however, 
the leaves may persist and not become discoloured. Seedling 
trees were found most liable to the disease, and the Lemon is 
specially subject. The Lemon leaf figured in Plate VI., Figs. 
1 and 2, was gathered at Corroy, in Queensland, on the 3rd April, 
1898, arid is rather remarkable for the crop of fungi found upon 
it. There were numerous ruddy-brown scabs, mostly aggregated 
along the midrib or near to it, and also along the margin, 
occasionally solitary, but generally run together, and forming 
irregular, elevated masses on both surfaces of the leaf. A few 
scabs also occurred on the petiole. The terminal portion of the 
leaf was pale and withered, and the whole had an unhealthy 
appearance. 
Six fungi were found on the leaf altogether, four associated 
with the scabs and two on the withered tip portion. They were 
as follows :— 
1. Phyllosticta scabiosa. 
2. Sphaeropsis citricola. 
3. Pestalozzia funerea. 
4. Sporodesmium triseptatum. 
5. Colletotrichum glocsporioides. 
6. Sphaerella citricola. 
The main object of the inquiry was to discover the cause of 
the extensive scabbing. Mr. Tryon found a remarkable scarlet 
Mite present, and this he believes to be the primary cause of the 
scab-like bodies. Then the question arises, are the fungi found 
in connexion with the scabs of the nature of saprophytes, settling 
down upon the galls produced by this particular Mite ? From 
the nature of the fungi concerned there is no definite evidence to 
connect them with the production of the scabs ; and, taking all 
