3^9 
of rubber from the latex and the difficulties that are encountered 
therein. 
fTo be continued.) 
THE CANKER FUNGUS IN RUBBER. 
A lecture by Mr. J. B. Carruthers, Government Mycologist, to 
the Kalutara Planters Association, Tebuwana, Ceylon. 
Mr. Carruthers’ Address. 
Mr. J. B. Carruthers, who, on rising was received with ap- 
plause, said : Gentlemen, to begin with the history of the disease, 
I may mention that it was first noticed two years ago by the Assis- 
tant Conservator of Forests of the Province of Sabaragamuwa ; but 
it was not till some live months ago that my attention was called 
to it. Following this various diseased speciments of rubber were 
sent to me from a number of districts, and, in some of these speci- 
mens, I found the nectria or canker fungus. The specimens sent 
contained mycelium, and, on investigating this by means of cultures, 
I found spores, which, on scrutiny, showed that they belonged to a 
species of nectria. 1 then made inoculations on trees, and that is 
the only way to prove the guilt of an individual parasitic fungus as 
the cause of any disease. Nectria grow on apple trees, plum, 
cacao, tea, etc., etc., and affect and eventually fill many kinds of 
trees. 
After these preliminary investigations had been to some extent 
finished in the laboratory at Peradeniya, I visited Kalutara and 
went over some fifteen or more estates, and have seen practically 
all the rubber estates of any size. The result of this inspection is 
that the estimated proportion of diseased trees in the Kalutara dis- 
trict is about one in two-hundred or \ per cent. Yatiporua and 
lcdengoda estates on the other side of the river are not included in 
this record. If they are included it would about double the per- 
centage and make it over I per cent. Yatiporua has about 40 per 
cent, trees affected by canker and Edengoda 20 per cent. The 
canker has been there for some years, possibly five or even more. 
Details of the effects and structure of the fungus will be given in a 
circular of the Royal Botanic Gardens, so that there is no need for 
me to lake up your time with these. Coming now to observe the 
aspect of the disease on trees, as a general rule the external ap- 
pearances on the rubber tree are roughened and swollen places in 
the stem and branches. These, on cutting off the outer bark, show 
discoloured tissue, at first a neutral tint colour, and afterwards 
brownish and claret colour. When shaved the whole of the diseased 
parts are shown up like an outlined coloured map in the lighter- 
coloured healthy tissue. When the canker fungus has been grow- 
ing in such a spot for some time — I cannot definitely say how long, 
as this depends on physiological conditions — the fruits are produced, 
at first pink or whitish spores, and later round red fruits like 
A-V 
