5*2 
THE TROPICAL 
AGRICULTURIST. [December i, 1881. 
The Peradeniya Experiment. 
§ 17. In order to have a second experiment performed 
of the same nature as that on Harrow, a piece of coffee 
was selected on Peradeniya estate in June 1881, and 
half the piece treated as before. 
The coffee chosen covers a narrow, oblong tract of 
16 acres. It is described as good coffee, and at the 
time the experiment began had a fair crop on the trees. 
A great deal of trouble was spent in obtaining equal 
areas for experiment, as the ground is somewhat broken 
by hollows, ridges, and patches of grass or stones. 
A line was marked by driving stakes into the ground, 
dividing the 16 acres longitudinally ; the half which 
was treated lies generally to the north of the other half. 
The sulphur and lhne were applied on July 6th, 7th, 
and 8th, and the experiment was completed on the 16th, 
rain having come on and interfered with the application. 
The whole area is fairly sheltered, but the S. W. blows 
across the lower end as if from S. to N., therefore 
blowing across the unsulphured patch first. 
The soil is stony and light as a whole, and some- 
what shallow in places ; and the coffee is somewhat old. 
Leaf disease was becoming very bad when the experi- 
ment began, and much "rust" was present on the leaves. 
The area was manured with bulk (cattle and poonac) 
in January 1880, and gave little crop last season. 
On July 15th no change was discernible ; the field 
was yellow with rust, and the sulphur and lhne first 
put on were washed largely to the soil by the rain. 
Examination of given leaves demonstrated the activity 
of the reagent. 
On July 26th I again saw the coffee. Many leaves 
were falling in the hot, dry weather, and although Hemi- 
leia was still abundant, the manager (Mr. Huxley) 
thought the strip was looking better. 
During the first week in August, the bad leaves had 
fallen for the most part, and the new leaves were already 
making the coffee look darker ; but at the end of the 
month a decided though slight difference in colom- could 
be detected on either side of the line of stakes : this 
was most evident on one of the later treated parts. 
About the middle of August, however, a fresh " attack 
of leaf disease " had broken out all over the field, and 
it became clear that the benefit, so far as external 
aijplication was concerned, would be partial and temporary. 
This follows, also, from the other facts. In apply- 
ing sulphur and lime on July 8 — 16, those spores and 
tubes were destroyed which would have produced spots 
about August 1st and later. The rain, however, broke 
into the experiment (and it is clear that no application 
could be made then), while spores did not cease to 
arrive and break forth from mycelia already inside the 
leaf, and the consequence was a new outbreak about 
the middle of August. Of course the good done made 
itself visible — germination was, at least, to some extent, 
delayed, and the cleaner leaves showed forth and dark- 
ened the cokyur. 
It remains to be seen how much benefit will be de- 
rived from the experiment in the end. The crop from 
each field is being kept separate, and it will be pulped, 
(fee, separately. This cannot be decided before the end 
of the year. I am strongly of opinion that the darker 
colour, which is now increasing, is due to the action 
of the lime on the soil, and the absorption of lime 
and sulphur salts, <fec, by the roots.* 
Experiment on Belgravia Estate. 
§ 18. Acting on suggestions derived from preceding 
experiments, the following plan was adopted, and Mr. 
Elphinstono kindly undertook to have it earned out on 
Belgravia estate, Lindula. 
A square of coffee was selected hi April consisting of 
trees as equal as possible and situated on a flat sur- 
rounded by sheltering bills. About 100 trees were en- 
f The results will be watched and reported upon, if 
necessary, at the end of the season. 
closed in a square of canvas arranged as follows : stout 
posts driven into the earth at intervals of a few feet 
supported two lengths of canvas or ceiling cloth three 
feet wide, carefully nailed on and joined. Hence the 
enclosing wall was six feet high. 
The wind of the S. W. monsoon comes in at one 
corner, and blows diagonally across the square. The 
soil is fan - , but somewhat moist at this spot. All the 
leaves and prunings were carefully removed from the 
enclosure, and leaves were buried in the soil. 
The enclosure was completed in May, and a consider- 
able number of "rust-patches" were already on the 
leaves all over the enclosed and surrounding coffee. On 
May 18th the whole inside of the enclosure was treated 
with sulphur and lime, thrown by hand into every tree, 
and on the logs, ground, and canvas. Microscopic ex- 
amination demonstrated the destruction of the germinat- 
ing spores as before. 
At the end of June the enclosure showed no marked 
difference to the unaided eye, and it became clear that 
the disease was very little reduced inside the square. 
On August 13th I again visited the enclosure. Looked 
down on from above, the colour of the coffee was darker 
under the lee of the corner wiiere the wind caught the 
square, and became paler towards the opposite corner. 
Careful examination showed that the trees in the more 
sheltered comer had less rust on the leaves than those 
in the opposite corner ; at the same time no one could 
undertake to say that the most diseased comer was 
more free from the rust than the coffee immediately 
outside and partially sheltered by the whole square. 
It was perfectly evident, in fact, that whatever good 
had been done by the application of sulphur and lhne 
on May 18th, it was only a transitory benefit ; the 
coffee had become re-infected, and was nearly as bad as 
ever. In short, one application of the reagent was clearly 
shown to be insufficient. 
On reflection, and as the facts already detailed in this 
report became known, the explanation of this disappointing 
fact revealed itself to the following effect : — 
1st. — It is clear that those germinal tubes which were 
already in the leaf wiien the application was made were 
safe from the effects of the reagent, and would produce 
spores (according to the knowledge now to hand) some 
fortnight to three weeks later. Hence there wotdd be 
the means of re-infection already inside the enclosure, 
unless the sulphur and lime acted long enough to catch 
the new spores also. This it did not do at that season, 
being largely washed off dming the monsoon rains. 
2nd. — These newly-produced spores would germinate in 
the rains and their tubes enter the leaves forthwith, and 
within another three weeks — i.e., six weeks after the 
original experiment — produce a second stock of spores. It 
must be remembered that the six-feet wall of canvas could 
not prevent some motion of the trees by windand a conse- 
quent shaking of the spores on to suiTOunding leaves. 
3rd. — From the fact that the comer of the square 
furthest removed from the point where the S. W. wind 
first touched the whole, was most diseased on August 
13th, two conclusions might be drawTi ; either the greater 
shaking of these trees by the Mind enabled the spores 
they produced to fall more freely around, and therefore 
to infect more leaves than was possible among the trees 
in the sheltered comer ; or, the greater amount of in- 
fection was due to the advent of spores derived from 
without, the wind passing over the sheltered trees hav- 
ing dropped spores into the more exposed comer, and 
provided for more disease spots in proportion. 
Examination of the canvas demonstrated that the 
last explanation holds good. I took pieces from both 
the upper and lower portions, and found numerous spores 
of Hemileia embedded in its meshes, and in all stages 
of gennination and decay, as well as quite recently 
blown and fresh specimens. 
The Belgravia experiment, therefore, may be held to 
prove, (1) "that one application of the reagent can have 
