July i, 1881.] 
THE TROPICAL AGRICULTURIST. 
COFFEE LEAF DISEASE. 
We have more than once pointed out the close 
affinity which subsists between the fungus which is 
known as "the potato disease" and Hernileia vastatrix, 
the great enemy of coffee in these modern days. 
The history of the one fungus is precisely that of the 
other, ODly that the one has existed for forty years, 
and the other twelve, and that more minds have been 
directed to the investigation of the older pest than 
to the later arrival. The scientists, however, agree 
in the circumstance that up to date no remedy has 
been found for either, nor — if we take European 
experience as our guide — can we be sanguine of one 
being likely to be found in the direction of local applica- 
tions. The result of Mr. Ward's and Mr. Schrottky's 
experiments has yet to be seen, and we most certainly 
wish them all success ; but it is uphill work trying 
to accomplish for a perennial fruit-bearing shrub in 
the tropics, afficted with fungus what al] the science 
of the West has been unable to accomplish in refer- 
ence to so important a vegetable, and annual, as the 
potato. One fact stands forth in the history of all 
blights, so that those wbo run may read. The oidium, 
the phylloxera, the potato fungus, the cofTee bug, the 
Hernileia, and we suppose the grub, too, have all ap- 
peared, spread and multiplied, where large tracks were 
under one species of plant. If this can be proved to 
be connected with blight, as an ever-associated fact, 
it may be fairly assumed to be one of the causes, 
till it is proved an error. But, at the same time, 
we cannot forget that blights have apperead, spread 
far and wide, done immense damage, and then dis- 
appeared, as mysteriously as they came. We must 
therefore conclude, that great breadths of one cultivated 
plant do not complete the sole cause of blights, some 
passing condition of the soil, the atmosphere, - or the 
electric currents, may operate to the rapid multiplica 
tion of an insect or parasitic fungus ; which, com- 
bined with the great quantity of food provided for them, 
may give the whole of the conditions necessary to 
make a destructive blight. If such conditions do exist, 
they probably lie too deep for science with its pre- 
sent powers to reach, and if they were discovered, 
they might fiually be found beyond human control. 
The one warning that the cultivator can in the pre- 
sent avail of with certainty is to mix his species, 
and, instead of one prociuct, have twenty, if he can 
find so many that will pay for the ground they occupy. 
This ha3 indeed of late years been the course our 
Ceylon planters have taken, and it is to be hoped 
none of them in the future will plant large unbroken 
breadths of any one plant ; for, let it be remembered 
by cinchona, tea, Liberian coffee, and coco 1 planters 
that what are known as "new products" are just 
as liable to blight as coffee, if the conditions are | 
created. Tbo spread of canker in cinchona seems to 
be a case in point, although we are aware that the 
most diverse opinions exist on tho subject : — -some, 
liko N'ir. Forbes Laurie, for instance, believing that 
close continuous planting over a considerable area is 
a direct inducement to the disease ; others, again, that 
it is all a matter of soil and drainage, tbe disease 
being neither infectious nor contagious ; while Mr. 
Morris of Jamaica in his last lieport writes indirect 
support of close planting as producing the healthiest 
and most thriving plants. Returning however to coffee 
leaf disease, we have to lay several contributions on 
the subject before our readers to-day, including (in 
order to gratify, and, wo trust, finally dispose of our 
correspondent) one from Mr. Oliver Jones, of Dindi^ul 
Medical School, who is so determined to hold all the 
scientific and planting world wrong in regarding the 
evil wrought on the coffee leaves as the work of a 
fungus instead of. as he lias found to his own sa'is- 
32 
faction, an insect. Mr. Jones' letter will be found to 
afford amusing, if not very instructive reading! 
Since writing the foregoing, two letters from planters 
in Fiji have come to hand, and it will be observed 
that Mr. Storck adopts a tone of the utmost confid- 
ence in reference to his discovery of " a cure " for 
leaf disease. We shall certainly await with interest 
this gentleman's further experiments in Fiji, and when 
he has cleared the group of coffee-bearing islands in 
the South Pacific of the fungus-pest, Mr. Storck will 
be most welcome to try his hand in Ceylon, although 
the rate of £4 per acre even for " a perfect cure " 
is rather high. 
LEAF DISEASE AGAIN : MR. OLIVER JONES' 
MOTH THEORY. 
(Communicated.) 
It used to be a favourite simile in the good old 
times, the likening of truth to a rock. Our worthy 
forefathers meant thereby to indicate that there was 
something substantial and abiding about it, something 
that could be bandied and held on by, and if you 
came again and again, it would be found still there 
immovable and unchangeable. 
It would appear, however, that in this rapidly pro- 
gressive age scientists have come upon new forms of 
truth, which are as Protean in shape, and unsub- 
stantial in essence, as cloud or gaseous matter. 
Witness the history of coffee leaf disease. It seems 
a long time now since the scientist pronounced the 
red dust a fungus, and described all it-* parapher- 
nalia of sporidia, mycelia, and all the rest of it, and 
prescribed sulphur in fumes or otherwise as a poison 
that would be the death of it. By-and-bye, lime was 
added to sulphur, to kill it twice dead as it were, 
so that, turn as it might, the disease found sure 
death on the one hand and no mercy ou the other. 
It is as unnecessary as it is painful to relate that 
the disease escaped death notwithstanding. 
Then came more scientists and found that there had 
been some dodging on the part of the mycelia or 
something or other, and one of the said learned men 
began sending carbolic acid solution or dilution up the 
bark of the trees to catch and choke every sporidical 
mycelia dodger of the lot in their "howfs"— in the 
cells of the leafs and slay them all outright. Next 
came the vaporization to smother them as they emerged 
from their hiding-places. 
Then science, under the guidance of the learned, 
detected new phases, and sulphur and lime were again 
in demand. 
Now comes an embodiment of multifarious science 
from Dindigul, and after following truth with watchful 
eye as it went through its various evolutions, he has 
detected that the whole thing is a moth and its 
I belongings, and the sporidia are no fungus at all but 
mere dirt, aud the mycelia only the threads of silk 
spun by the said creature. And the medicine that is 
to do for that moth is ready ; yclept in apothecary 
lingo "cocculus indicus and camphor." 
This might be all very well, but there are others 
again who affirm rhat the sporidia are real fuugi, aud 
find their way into the mouth of the moth, instead 
of " tother way." 
Now all this, of course, is very interesting to those 
who are engaged in the pursuit of science, but what 
can non scientific folks like in make of it all ? They 
may all be right, but one is tempted to think that 
some one of them has got hold of the wrong end of 
the thing. Yet when they get so little out of tho 
modes of truth (it used to bo modes of error in olden 
times), how can plain unscientific men "make head 
or tail of it " ? 
Tbo Dindigul seienti-it dwells ou tho advant ige? oi 
I a theory, anil a theory has ju9t occurred to me. Iu 
