136 
THE TROPICAL AGRICULTURIST. 
[July i, 1881 
which seems to follow the treatment' will make the 
area loss liable to suffer from the disease during the 
next favourable period for its development. 
But still I would advise that four applications cost- 
ing a total of R16 to R20 per acre, including every- 
thing, should be given during the first year. An ex- 
penditure of B8 to RIO or even less the second year 
should suffice. The preparation and application of 
the powder is extremely simple. The cooly under- 
stands it readily, and, though disagreeable work does 
not object to it ; so that under average intelligent 
management I believe it perfectly feasible to battle 
successfully with leaf disease with the above reason- 
able expenditure. 
The degree of success obtainable will depend on 
how nnd when the applications are given. 
Detailed instructions as to bow and when this 
treatment should be applied will form the subject 
of another paper which I have under consideration, 
and which I hope to finish after another visit to 
the estates that I have treated, before my departure 
to India. 
The fungus will best be regarded in the light 
of a weed which has been allowed to over-run and 
firmly establish itself on an estate. It will involve 
some trouble and a good deal of expense in the first 
instance to try and keep it under, but in the natural 
course of things the damage done by it ought to be 
sensibly reduced at each periodical attack following the 
treatment I have recommended ; and the cost of keep- 
ing it out of a certain area, when operations are 
carried on over an appreciable extent, will be after 
a year or eighteen months very trifling. For though 
the danger of infection from neighboiiring untreated 
estates is considerable, the spores tlius re-introduced 
into a treated area will amount only to a very small 
fraction of the countless millions of spores that are 
accumulated by unhindered growth and fruition of 
the fungus within a given area. It is almost need- 
less, I think, for me to add that disappointment will 
result if any planter thinks he has only to scatter a 
bandful of powder over one part of the estate, to 
see the disease disappear out of the other part. But 
once the battle is earnestly begun, there are two 
qualities that will ensure success— Patience and 
Perseverance. 
The following records and reports of the observation 
of the different planters with whose assistance I carried 
on my experiments and who tried and tested the treat- 
ment as finally recommended will, 1 trust, be accepted as 
independent testimony that my conclusions are based on 
data and results, that were apparent not only to the 
trained eyes of an experimentalist, but which were also 
apparent to the careful and intelligent observation of 
practical planters. 
The cause and effect of the vaporization treatment 
with carbolic acid on the incipient forms of the 
fungus when established in the tissue of the coffee 
leaf cells, and of reducing the susceptibility of the tree 
to the disease, I find exactly the same as in case of 
the inoculation process. The observation and results of 
the experiments made with the latter process may 
therefore be fairly accepted as proof of the merits of 
the former in that respect, when operations are made 
under circumstances that admit of the vapjr breathed 
and abaorbed into the system of the tree. 
INOCULATION PROCESS WITH CARBOLIC ACID. 
Dotelova Estate. 
Operations on a Few trees only. 
Observations on the fruiting of healthy pinspots : 
On treated coffee trees, none fruited ; most dried up 
and turned brown. Untreated cp flee trees— 83 percent 
fruited. 
• Results examined by Messrs. James Blackett and 
John Drummond and testified by James Blackett. 
12th December 1880. 
Bellowjalla Estate. 
Operations on one acrj. Observations on the fruiting 
of healthy pinepots specially marked for observation : 
On treated area— 87 per cent did not fruit, most dried 
up, 13 per cent had thrown out a few isolated spores. 
On the adjoining untreated area— all the pinspots had 
fruited, additional pinspots and already developed 
spore patches had formed. 
General Observations : — Progress of disease on treated 
area decidedly checked; progress of disease on untreated 
area at the end of ten day3 about 300 per cent. 
Results examined and testified by Alex. Thom. 
28th December 1880. 
Extract from letter to myself: — " I certainly think 
the trees which have been inoculated are freer of leaf 
disease, either in the pi' spot or red rust stage, than the 
adjoining untreated ana, but so far I cannot say 
that the inoculation of carbolic acid has eradicate! 
the disease." W. D. Gibbon. 
5th January 1881. 
Morayall i Estate. 
Observations on the fruiting of pinepots : — no effect 
of treatment observed on old shuck trees, nearly all 
pinspots fruiting. On the main area treated, not on* 
of the pinspots fruited, spots turning brown. 
Results examined and testified by Mr. Geo. Sloan 
Paxton. 
29th December 1880. 
Fairieland Estate. 
Observations on healthy, specially marked pinspots. 
Treated area — In no single instance had any of the 
pinspots thrown out any spores. The pinspots them- 
selves had turned brown and were pronounced (and in 
this all were guided by Dr. Thwaites' decision) to have 
been injuriously acted upon. 
Untreated adjoining area — In nearly every instance 
had the pinspots on this area thrown out spores, a 
few only had not done so. 
Results examined by Dr. Thwaites (late Superin- 
tendent, Botanical Gardens), Messrs. Anderson, Dewar, 
and Pyper and testified by 
J. Lewthwaite Dewar 
13th January 1881. and Gordon Pyper. 
Roseneath Estate. 
Observations on pinspots : Treated area — 22 per cent 
of pinspots fruited, the rest did not. 
Untreated area — 76 per cent fruited. 
Result examined by Messrs. Anderson, Dewar and 
Pyper, and testified by 
J. Lewthwaite Dewar 
13th January 1881. and Gordon Pyper. 
Sufficient evidence being now collected to establish 
that the checking of the progress of the disease, as 
evidenced by the non-fruiting and the dying off of 
the pinspots, in the treated area, was due to the treat- 
ment and not to accidental natural causes, comparative 
minute observation on adjoining untreated area, 
except broad comparison as to the prevalence and 
state of disease and general appearance of the coffee, 
was considered by me not further necessary. 
Pallekelly Estate. 
Observations on healthy, specially marked pin 
spots : Out of 183 pin spots, only 11 had thrown out 
a few isolated spores which looked pale and un- 
healthy. Nearly the whole of the pinspots had been 
affected and had turned brown. 
Results examined by Messrs. Vollar, von Kriegs- 
heim and Gibbs and testified by Mr. H. J. Vollar. 
14th January 1881. 
Peradenia Estate. 
Inoculation followed upon the 4th day by vaporiza. 
tion. Observation on healthy pinspots and bright 
orange coloured rust patches: "No single pinspot" 
on the marked leaves had thrown out spores, large 
majority showed a brown patch in centre, and were 
to all appearance dead. Bright spore patches bad 
