December i, 1881.] THE TROPICAL AGRICULTURIST. 
549 
»A (JURE FOE HEMILEIA VASTATRIX? 
MR. SCHROTTKY'S EXPERIMENTS WITH 
i, TI 
arc <lr 
parent 
tho su 
leaf fn 
of Ce; 
tropic 
those 
had been dis 
rapidly oversp 
about twelve 
a surprise to 
Berkeley's ins 
to the name 
term which hi 
destroyer of t' 
shews how pc 
apparently coi 
fungus which 
great enterprii 
has appeared 
far islo of thi 
coffee. Mr. \ 
the fungus- hi 
is closely alii 
i with 
rth of 
n very minute and 
mcies may be. The 
terrible injury on a 
uthern India, which 
i, and even in that 
to confine itself to 
oother plant on which 
re believe that plant 
3 the doctrine of spon- 
t, we seem confined 
taneous generation is out of court, we sc 
to tho conclusion (originally arrived at by Dr. Thwaites), 
that up to 18G0 tho fungus existed on the indigenous 
coffees in our jungles, but in a low and latent form. 
What cause or combination of causes, in the shape of 
atmospheric or other influences, gave the fungus such 
virulent activity in 1860, is, as we have said, still a 
mystery unsolved. But all the evil effects which Mr. 
"Ward attributes to wind (the worst of the triad of 
Heaters' foes : " wind, wash, and weeds ") may justify 
the guess that the opening up of large expanses for 
<joffee culture favoured tho rush of wind into such spaces, 
tho moving air first passing over forest containing trees 
infected with the fungus and carrying the spores on 
its wings. This is what the wind does now in career- 
lag over fields and plantations of coffee, and perhaps 
the most important lesson to be derived from the 
elaborate reports of Mr. Marshall Ward is the necessity of 
providing for our coffee fields that shelter of which it 
Kfl a mistake ever wholly to deprive them. We arc 
familiar enough with the difficulties, objections, and rea- 
sons which led orthodox planters to leave nothing on 
their plantations but coffee. Of course tho extensive 
cultivation of cinchonas on coffee estates has to some 
e\lr it remedied tho inistako which was made. But ciu- 
ohouas themselves require shelter, and vast numbers either 
die out or are cut down or rooted up year by year. 
The time, then fore, seems to have arrived for lining nil' 
plautatimiH into moderately sized squares by means of 
the rapidly growing eucalypti and acacias of Australia, 
I trees which combine rapidity of growth with a good 
quality ..f timber al a comparatively easy stage of growth. 
I Those w ho believe in tho doctrine of cycles will not for- 
WF Bee Mr. Sohrottky'a letter on pago 516. 
got that leaf disease has now been ravaging our coffee 
for over eleven years. A decrease in the virulence of 
the pest, therefore, may be now confidently expected. 
And even those who doubt the cycle theory must admit 
that pests of a like nature, the coffee bug for instance, 
have abated into comparative innocuousness with " effluxi- 
on of time." But, virile looking for relief to ' time the 
healer," judicious cultivators will not neglect any one of 
the lessons which t 
tions of scientists 
some feeling of do: 
told that manure 
ledge that much o 
11 experience aud the obscrva- 
;aight. We can understand 
' impatience, when planters are 
ust, although with the know- 
manure they apply will go to 
feed the parasite instead of the plant. Culture, prun- 
ing, and application of remedies, too, must be so at- 
tended to as to induce the tree to put on and mature 
its foliage in advance of the period when the winds of 
the monsoons blow tho spores on to the leaves, while 
the moisture of the monsoons favours the rapid germina- 
tion of such spores. The better grown the leaves on 
a tree are, the better able they will be to resist the 
insidious fungus. It will be gratifying to Mr. D. Morris 
and his friends to be assured that the effect of Mr. 
Marshall Ward's extended experiments and careful re- 
seaich is to confirm the value of a combination of caustic 
lime and sulphur, resulting in the production of sulphur- 
ous acid gas, as a remedy for the fungus. It would 
be " a perfect cure," if we c< 
existing spore, for certain it 
sulphurous acid gas reaches, 
total destruction is the ph; 
universal application ; while 
sucl 
worse than in their first seems 
tree freed from the debilitating 
put on a largo crop of foliage, 
not itself protected by the app 
the appearance of the tree when re 
portion to the number of leaves i 
al in keeping fields of coffee or 
from fungus aud its debilitating i 
apply it to every 
ery spore which 
3. The limit to 
possibility of the 
1 applica- 
.cial to such areas as 
isiderations of finance 
lime aud sulphur, aud 
> in their last state 
ie to the fact that a 
fungus is enabled to 
md if that foliage is 
cation of the remedy, 
nfected is bad in pro- 
carries. To be effoctu- 
ihole plantations free 
lects, the envelope of 
I sulphurous acid gas must be kept up by frequent applica- 
I lions of Urn: ani sulphur, at shortly succeeding inter- 
vals. The effect of " the interactions of sulphur and 
freshly burnt lime on the moist leaf " are thus enumer- 
I a'.ed in Mr. Marshall Ward's latest — we are sorry to 
i believe his last — Report : — 
(1) The mixture is slowly continuous in action for a 
long- time. 
(2) The slowly •evolved gases distribute themselves 
ri pialy l>y diffusion. 
tfh The chief gases arc very readily dissolved in water. 
(1) The solution formed is 'strong enough to kill the 
go minol tubes, but too weak to injure the leaf. 
(5) The acid solution does not concentrate to « danger- 
ous strength, since it is con'inually bom? absorbed 
by porlions of the lime, aud the compounds bo.otne 
further exydised to neu'inl or nearly neutral salts. 
(f>) Ni t onlv are tho final products harmless to thr tree, 
but tho chief one (.sulphate of linio) is a valuable 
manure. 
(7) The mixttiro is simply and reu lily applied by coolies' 
hands. 
Tho morits of Sulphur and lime being thus so great, 
it is unfortunate that the cost of purchase carriage and 
