July i, 1881.] 
THE TROPICA! AGRICULTURIST. 
i33 
COFFER LEAF DISEASE. 
The abeence of sufficient time is likely to prevent 
the Chairman of the Planters' Association and his 
fellow-Committee members from visiting the scene of 
Mr. Schrottky's experiments in tln> Dumbara Valley 
before Thursday's meeting. But the work done should 
not be overlooked on that account, and the members 
generally cannot but feel obliged to Mr. Sehrottky 
for the paper lie has drawn up for them with a 
resume of his experiments and their results so far as 
he and the planters associated with him have been 
able to judge. Wo have no doubt his statement will 
be carefully considered, and at the very least it calls 
for acknowledgment at the hands of the Committee 
with an expression of thanks to the gentleman who 
has devoted so much of his time to the service of 
the planters without any prospect of direct remuner- 
ation. We do not know how far Mr. Sckrottky's 
confidence in his vaporization process will be shared 
among members of the Association, but certainly so 
far as the estate reports go, the results up to date 
are favourable. Most people however, we suspect, 
will reserve their judgment until the period for an- 
other attack on the large areas recently treated has 
passed over ; but that reserve should not prevent 
due notice being taken of the good work done and 
the satisfactory results already obtained. 
COFFEE LEAF DISEASE. 
MR. SCHROTTKY'S SEVEN MONTHS' 
CAMPAIGN. 
To the Chairman and Members or the Planters' 
Association of Ceylon. 
Sirs,— When in November last, while on a tourist- 
ical visit to Ceylon, I decided to make use of a 
month's leisure, to institute with the help of some 
practical planters a series ot experiments with the 
view to determine, whether it was really beyond the 
reach of Chemistry to give Coffee Planters a remedy 
or palliative of coffee leaf disease (this most dire in- 
fection) 1 had no idea that the work would occupy 
seven months. 
I came very early to the conclusion that science 
in this case would not be so helpless, as she is 
generally represented to be, and that the disease 
(being fairly accessible) could not only he topically 
destroyed by a number of chemicals, but that the 
conditions of the sap of the tree could be artificially 
so altered as to make it less favourable to the de- 
velopment of the disease in the leaf cells. But to 
reduce this conclusion into a practical form, to de- 
vise a practical and cheap method of using any of 
these chemicals as topical applications or otherwise, 
and after having found a method, to obtain such 
proof of the results of the same as would be readily 
understood and acknowledged by practical men :— this 
1 have found an arduous task which 1 more than 
once despaired of bringing to a satisfactory conclusion, 
and which has occupied a time that I have only 
been able to give to it by greatly neglecting and sacrificing 
my interests elsewhere. 
With some professional repute engaged, I was 
naturally reluctant to leave such an important work 
hall done, and with its practical issues involved in 
donbt. It. is therefore with more than ordinary 
pleasure, that I proceed now to sum up the results 
these experiments have yielded up to date, and which 
I think warrant some very satisfactory conclusions 
regarding the method 1 recommended for the miti- 
gation, if not prevention of loaf disease, viz. vaporiza- 
tion with Carbolic Acid. 
Having a practical object in view, I have investi- 
gated the whole subject (as far as I wus able, having 
34 
only a general and not a special knowledge of Myco- 
logy) mainly from a pratical point of view, and 
desiring to make this paper as short and concise aspossi- 
ble, it will, I hope, be understood that my main conclu- 
sions though stated in a few words have not been arrived 
at, without full consideration of every fact that I have 
been able to observe myself, or been able to collect from 
such of the planters whom it has been my privilege to 
meet in my seven months' study of the subject. 
THE FUNGUS. 
As described generally by mycologists, and more 
specially by Mr. Marshall Ward, what is known as coffee 
leaf disease is a parasitic fungus (Hemileia vastatrix) 
propagated by spores, whose germinal tubes when in 
contact with the lower surface < f a living coffee leaf, 
enter into its stomata, establish themselves in the inter- 
cellular tissue, develop at the expense of the cell sap 
into mycelium which finally forms a receptacle (che 
Uredo) from which arise and break through the epi- 
dermis of the leaf, kidney-shaped orange-coloured 
Uredo-spores, forming clusters of what constitutes the 
well-known rust. J be same mycelium also produces a 
secondary spore, the Teleuto-spore. 
Before fruiting the presence of the fungus or rather of 
its mycelium in the leaf tissue, is evidenced by pale- 
yellow circular spots (called pinspots) transparent or 
opaque. The healthier the disease, the more opaque the 
spot. 
The fungus has been classified (by Berkeley and Broom 
I think) as belonging to the Uredinese. An)' doubt as 
to whether this classification is correct has been re- 
moved by Mr. Ward finding the Teleuto-spore, 
It is, therefore, perfectly reasonable to look forward 
to Mr. Ward (the mycologist specially engaged in 
Ceylon in the investigation of the different forms of 
this fungus) describing to us, before he closes his work, 
the three different cycles of generations of this fungus, 
and the other hostplaut on which the transition takes 
place, this being a distinguishing feature of the Ure- 
dineoi. 
But what makes this disease so formidable an enemy 
is the peculiar capability of the Uredo-spores for rust) 
to reproduce themselves indefinitely by their constant 
germination and reproduction without the necessity of 
passing throng the cycle of generations. These orange- 
spores, of a heavy oily character, germinate in con- 
tact with moisture (dew, rain, etc.) and their contents 
p;si into a germinal tube. The spore becomes au 
almost empty cell, and the whole fabric is then ex- 
tremely light and capable of wide diffusion. 
Wind is, in my opiuion, the chief cause of the dis- 
semination of the spores before, but far more so (on 
account of their lightness) after germination, from one 
disease spot to another, from one leaf to another, 
from one tree to another, from one field to another. 
As far as I have observed, and from information I 
have collected, the leaf disease fungus spreads, dur- 
ing the periods favourable to the germination of its 
' spons anil to their establishment in the leaf, from 
chronically diseased centres and travels in the direc- 
tion of wind currents 
The idea that an estate is absolutely free from 
disease for, say, three months, and that then 
it appears simultaneously nil over the estate, 
has, 1 think, its origin in untrained and de- 
fective observation and is greatly due to the extra- 
ordinary rapidity with which the disease spreads when 
all circumst mces are favourable. 
The germinated uredo-spore will not establish itself in 
an inoongenial nidus. Where congenial conditions do not 
exist, it will, even when over a stoma, simply dry up. 
We may take it for granted that, considering, com- 
paratively, force and direction of wind and neighbour- 
hood to diseased paits of an estate, each square inch of 
lower leaf surface of n coffee estate will receive an 
almost equal number of sports that maintain adber- 
