August i, 1891.] THE TR0P10KL AISmtSOLTURlST. 117 
As the work of destiuction is carried on within the 
leaf by the mycelium, it is quite evident that remedies 
applied after the spores appear on the epidermis of 
the leaf are useless : they must destroy the tissues 
to reach the foe within. Any agent to be of use 
must be on the leaf before the spore finds a resting 
place on it. 
When experimenting on the development of the 
spores on a coffee leaf, I took a clean seedling and 
raised it in a case prepared on Tyndall's method, 
with the result that I got a plant free from leaf- 
disease growing in sterilized soil. The spores only 
grew where planted on the leaf, nowhere else, and 
Mr. Marshall Ward's results were fully borne out. The 
disease is not constitutional : the spore of the parasite 
must be deposited on the leaf before the disease can 
appear. 
A weak tree suffers more than a strong one from 
the loss of its leaves ; and a tree weakened by injury 
to its roots, due to removal of the surface soil by 
wash, mamotie digging, or other causes, recovers less 
rapidly, and if the attack of leaf disease or succes- 
sion of attacks are virulent will in all probability 
succumb. The lower the vitality of the tree attacked 
the smaller its chance of recovery. 
A half -starved coolie readily falls a victim to fever, 
cholera &c., while if well fed he more easily resists 
the attack of disease ; so it is with the coffee tree. 
The conditions most favorable to the developement 
of the spores are a close, steamy, hot, stagnant 
atmosphere, with a subdued light. 
Heavy dews followed by hot days, if a dense shade 
is over the coffee, aid in the fructification. 
As a rule leaf disease is bad in South Coorg twice 
a year : just after the early rains, and during the 
autumn showers. In the hot weather we are practically 
free from it, though I have found the disease spots 
and rust patches in every month of the year. 
Shade under which the coffee of South Coorg is 
grown affects the disease in two ways. 
It acts as a wind screen and retards the passage 
of the spores from one estate to another. If the 
coffee is one continuous sheet the disease may start 
at one corner of the estate and roll right over it 
when the climatic conditions are favorable. 
I have visited an estate on the first of the month, 
and though leaf disease was to be seen, it was not 
suffering to any extent; fourteen days after the estate 
was red from end to end, and by the end of the 
month it had resimied the appearance presented at 
the beginning. 
This estate suffered from these periodical attacks, 
which always began at one corner, and swept over 
the estate in regular progression. 
Further examination showed that it was not the 
only estate affected in this way ; and in every case 
the starting point of the attack was where the shade 
was thick, with damp and sour ground below. The 
air was, especially in the early morning laden with 
moisture, with often not a breath of wind. As the sun 
rose, the best possible conditions for the develop- 
ment of the fungus came into xjlay. 
Here shade did more harm than good ; being too 
thick it prevented the free admission of light, 
conserved the moisture to an undesirable extent, and 
aided greatly in the production of the moist heat 
necessary for the germination of the spores. 
Under the circumstances the course to be pursued 
was first to render the conditions unsuitable to the 
fungus, by regulating the shade, and draining the 
land; then apply the remedies. 
The reason why' the lower leaves of the tree suf- 
fer most, is that the great restingplace of the spores is 
on the ground, on the dead and dying leaves rest- 
ing thereon ; the coolies pick up spores and dust 
as they walk through the coffee, and the bulk of 
the spores find a restingplace on the lowest leaves. 
These are shaded by the upper branches and in- 
tercept more of the moisture evaporated from the 
ground so that in general there are not only more 
spores on the lower leaves but the closer they are 
to the ground the more favorable the conditions are 
for the development. 
Unless the ground and the jungle trees are treated, 
to say nothing of the neighbouring estates, it will 
be impossible to eri<i<^icate leaf diseoise. 
But an estate can be kept practically clear of the 
pest by one application to the ground and two to 
the leaves per annum. 
In France remedies are applied to the vine four 
times per annimi with great success. The work is ' 
not expensive ; only labour must be there to do it at 
the right time. 
The Hemileia vaslatrix or a fungus so closely 
allied to it that I can see no difference between them 
is to be found on at least three jungle trees. Un- 
fortunately I know next to nothing of botany, so can- , 
not classify them. It was on the goni (Ficus 
mysorensiti'!) that I first found the spores: whether 
these are the uredo spore or the second sort 
of spore which prefers another host I am not suffi- 
cently well up in cryptogamy to determine, but 
the spores taken from the goni and sown on the 
coffee leaf developed there, 
I had a few failures, in transferring the spores from 
the coffee to the goni, but on. the whole, results were 
-satisfactory. The atty (Ficus glonierata) when a 
young plant was taken could also be infected. If 
the leaves are old, the yellow spots may show in the . 
leaf, with but very few spores being formed. 
Liberian coffee, which has a much tougher leaf 
than the Arabian, displays much the same characters 
as the atty and goni. 
The damage done by the' Hemileia vastatrix is en- 
tirely that of depriving the tree of its leaves. You 
can make a coffee tree sick by varnishing its leaves 
on the under surface and so preventing its breathing : . 
consequently in selecting a remedy care must, bs 
taken that it does not clog up the pores of the 
epidermis. It would do more harm than good. Strip- 
ping off the diseased leaves ranks in the same category. 
A tree must have its leaves which are its lungs 
in good order or it cannot develope its fruits. If 
all the blossom that appears would set, crops of from 
five to ten tons per acre would be common. As a matter 
of fact only from one or _two to ten per cent set, 
and all of that does not come on. 
The true use of a maniu-e is to enable the tree to 
set its blossom, and to assist in the developement 
of a healthy bean. My experimental plots being 
systematically manured were able to set a larger pro- 
portion of the blossom than the estates, though both 
received the same work, the only difference being in 
the manures and .* Though pruned and 
handled down to the level of the estates, they had 
a finer show of leaf and wood, and recovered from 
an attack of leaf disease more rapidly. 
The results from the estate where leaf disease vfas 
worst, taking the crop of 1887-8 as the basis and 
stating results as percentages on that, for both plots 
and estate, we get the following result : — 
Year 1887-88. 1888-89., 1889-90. 1890-91. 
Estate 100 63-1 34-2 8-5 
Plot 100 90-9 239-5 36-3 
This shows the value of steady systematic manuring 
broadcast annually, and this year the plots have a 
splendid crop on them. 
It requires time, patience, and careful observation 
to get reliable results, and the results to be of value 
must form a series obtained by steady systematic 
work. Not knowing how the various manures would 
act on the coffee tree I began with only small plots 
of 3,200 trees, or rather the space occupied by that 
number when the estate was originally planted. 
Each manure acted on two plots of 100 trees each, 
and the results individually taken are not conclusive. 
Therefore I had to take for comparison the aggregate 
results, including good, bad, indifferent and the un- 
manured plots for comparison with the estates, which 
in most cases did not receive the manures I re- 
commended, owing to failure of the supply of fish 
and other causes. 
Now as to preventative measures. Steady systematic 
manuring annually holds the first place ; drainage ii 
in some cases quite as important, and the careful 
regulation of shade render the conditions under 
which the coffee is grown suitable to it, and 
unsuitable to the fungus ; then special remedies 
can be successfully applied. 
* A word which cauuQt be miwile out.— Ed. T.-il. 
