December i> 1881.] THE TROPICAL AGRICULTURIST. 
5°5 
COFFEE LEAF DISEASE: MR. MARSHALL 
WARD'S REPORT. 
Mr. Marshall Ward's final and (so far as it goes) 
exhaustive Report has at length seen the light. Dr. 
rprimen, it will he observed, is very severe on "blind, 
empirical, haphazard experiments (so called)." He 
would reject all notions of "cures" or "specifics" 
and would adopt rather ihc old adage "Prevention 
is better than cure," but, unfortunately, neither he 
nor the OryptOgamist throws much, if any, new light 
on the means of applying preventive checks. This 
motto is, indeed, one that came up very early in the 
discussion on Coffee Leaf Disease, the veteran Mr. 
R. B. Tytler using it, if we mistake not, some half- 
dozen years ago, to enforce exactly the same lesson 
of "c ireful cultivation and judicious manuring," which 
the Director of the Botanic Garden now seeks to apply, 
and which, iudeed, lias been repeated at intervals 
ever since Leaf Disease first troubled the coffee in 
18G9. It is because cultivation and manuring, as then 
practised, appeared to have no permanent effect in 
checking the fungus that the aid of science was first 
called in, and now, so far as practical lvsults are 
concerned, the great benefit planters will derive from 
the thorough investigation which has just been com- 
pleted is to learn that scientists are not able to do 
anything for them : — that they must just help them- 
selves according to sound rules of cultivation, beariug 
in mind what is said about burying diseased leaves, 
the planting of other trees among or alongside the 
coffee, well-dir cted and well-timed pruning, more fre- 
quent applications of manures in lighter quantities 
(according to Mr. Sinclair's sound recommendation), 
and the judcious use of caustic lime. Strangely enough 
the only curative ingredients that Mr. Ward speaks of 
with approval are our old friends " sulphur and lime" 
which Mr. D. Morris at the outset recommended for 
the destruction of his "filaments." 
Among the most, importaut paragraphs in the 
Report are those in which Mr. Ward discusses the 
beariug of well-timed "Manuring" and " Pruning " in 
counteracting the effects of leaf disease on crop. 
We are rather snrprised to find Mr. Ward giving 
special attention to the origin of Leaf Disease in 
order to dispel so-called popular and erroneous notions. 
We were not awure that Dr. Thwaites' explanation 
under this head at the very outset had ever beon 
seriously questioned, and one reason for assurance that 
the fungus bad not begun to feed on cultivated coffee 
previom to 1809, was that it had never come under 
the notice of the late Director, while, wlicn hemileia 
did appear, the rapidity with whicli it spread wherever 
a cofl'oo brush grew afforded conclusive proof that it 
could not have tronbled the coffee previously without 
being observed. Dr. Thwaites wrote so far back as 
Juno 1872, that ho had discovered the fungus on the 
nativ • wild coffee plant, and tin' fact that it must have 
in the first instance passed from a jungle pi nit (prob- 
ably in the Madulsima forest) to the cultivated coffee, 
has since then been generally recognised. "Cultivate 
highly and manure judiciously" was the burden of Dr. 
Thwaites' reoommondation in hi* first report on the 
subject, and the lapse of a decade has not much im- 
proved on his remedy. Nuvurthclea*. there can be no 
127 
doubt of the great value of the information now given 
by Mr. Ward. As Dr. Trimen says, the many ques- 
tions connected with the pest, which have been the 
subject of so much, and varied discussion during past 
years, aro now narrowed down to a very limited c>m- 
pass ; the life history is completely worked out, and 
science has given the practical agriculturist all the aid 
and information that can probably be expected from it. 
LETTER FROM THE DIRECTOR OF THE ROYAL 
BOTANIC GARDENS, FORWARDING A THIRD 
REPORT BY Mr. MARSHALL WARD, 
CRYPTOGAMIST. 
No. 29. Royal Botanic Gardens, 
Peradeniya, 19th September 1881. 
Sir, — I have the honour to forward to you a Third 
Report on Coffee Leaf Disease by Mr. Marshall Ward. In 
this he sums up the whole results of his investigation, 
which has extended over more than twenty mouths. 
1. Continuing in the steady course of direct ex- 
periment and observat ion, and avoiding everything in 
the way of conjecture or theory, the Cryptogam ist has 
now established the main facts of the true nature of 
this parasitic disease beyond dispute. Briefly, they 
are these. I caf disease itself is purely local and in 
no sense constitutional ; it is caused solely by the 
Hemileia. runs a short and definite course, and is so 
formidable from the cumulative effect of constant re- 
petition. The whole direct damage done by the fungus 
to coffee is loss of leaves ; other serious evils, however, 
and especially diminished crops, follow on from this. 
Cleared of many erroneous observations and inferences, 
the ordinary life-history of Hemileia is now shown to 
be of extreme simplicity, and the necessary conditions 
for, and exact duration of, each stage from spore to 
spore again have been demonstrated" with unfailing 
and convincing frequency. It is not too much to say 
that as regards the structure, circumstances and habits 
of Hemileia on the coflee-leaf we are now completely 
informed; and probably no fungus-pest has ever before 
received so prolonged and continuous an examination. 
2. This being so, I apprehend the stage to be now 
arrived at when remedial measures may be intelligently 
considered, and blind, empirical and hap-hazard ex- 
periments (90-called) to be no longer justifiable. We 
know that there is one sufficient cause of leaf-disease 
— the urcdospore of Hemileia vastatrix, that this is 
produced only by a previous one, is carried freely 
by the wind, may retain its vitality for several weeks 
or months, and can germinate only in moisture. This 
then is a vera causa, and, in accordance with 
the well-known medical aphorism, to remove this 
would be the true practice. Difficult and perhaps im- 
possible a3 this may be under present circumstances, 
Mr. Ward here urges several preventive measures 
acting in this way, and it is, in my opinion, the one 
which promises the best results to the practical and 
inventive capacity of coffee-plan: ers. Valuable guides, 
al90 in the same direction, are found in the close 
relations here clearly formulated between attacks of 
diseaso and weather. The portion of the report 
devoted to this subject deserves careful study for its 
obvious practical bearings, especially as to the question 
of the possibility of haviug the coffee-tree in the most 
suitable condition for resisting the effects of the growth 
ofthcpaia ite at the seasons of its chief invasions. 
3. Next to romovitm the cause como curative 
meacurcs. Mr. Ward bus done well to insist strongly that 
to find an agent that will kill Jlfinil< iii is not the most 
important or indeed a difficult tlung to do. Hut he 
has narrowed down the practically available chemical 
substances of this kind to a very few, ami his ex- 
periment* with them do not, in my opinion, lead 
