THE TROPICAL 
AGRICULTURIST. [December i, 1889. 
find out whether during one stage of its existence 
it does leave the Coconut tree, the tree it passes 
this stage of its existence on and during what period 
of the year, so that we might combat the fungus 
then. I am sure all interested in the question will 
be glad of more particulars from Mr. Potter and for 
a perusal of his paper. I shall make both public. 
And now I wish to address myself to Mr. Drieberg, 
the Principal of the School of Agriculture, who, I 
suppose, is still investigating the disease, and who I 
expect will shortly favour us with a full report on 
the subject. In his preliminary report he says, " I 
have no hesitation in saying that thorough cultivation 
is the surest way of combating the evil." He has 
just returned to the Island after a prolonged course 
of theoretical and practical training in Agriculture in 
Europe, and will be able to tell us authoritatively 
whether "thorough cultivation" has helped European 
Agriculturists to successfully combat the diseases that 
attack crops there. I read somewhere some time ago 
that experiments had proved that the Potato disease 
was due to a deficiency of Potash in the soil, and 
that it disappeared with a free use of Potash. Is 
this so ? Has not experience proved that in a flinty 
soil and also in one in which limestone abounds, 
rust is very nearly absent in wheat ? If this be so, 
it may support the theory I started at the very begin- 
ning that the Coconut leaf disease may be due to a 
deficiency of some plant food in the soil. It may 
be salt, or it may be something else. Analysis ought 
to settle that, or else why the disease is more viru- 
lent in certain areas than in others ? 
With reference to Mr. Potter's statement that some 
species of Phraymidium pass different stages of their 
life on different plants, I came across a confirma- 
tion of this accidentally in the first volume of the 
Tropical Agriculturist. Professor Buchanan de- 
nounced as a popular error the belief of peasants 
that the berberry tree was the cause of rust iQ wheat. 
He said that the peculiarity in the colour of the 
rust in wheat and of the fungus that attacked the 
berberry was at the bottom of the belief, but that 
no connection has been traced between them. Oersted 
and de Bray discovered that they were alternating 
generations, of the same species. Sachs and Prantt 
found out that the ureJo-spores of the rust in wheat 
are red. In the Autumn black telento-spores appear, 
then germinate exclusively on the berberry in the 
following Spring, and the cycle is completed by the 
appearance of uredo-spores with a mycelium on grasses. 
Rust of wheat requires au alternation of host plants 
to complete the cycle of its life history. It was 
supposed that the destruction of the berberry would 
not extreminate the rust, "for fungal parasites have 
have a wonderful power of adapting themselves to 
surrounding conditions, and a new alternating host 
plant might gradually be brought into use. " Fun- 
gal spores being excessively minute are transported 
by the wind, and a wheat field may get rusted very 
many miles from the neighbourhood of berberry plants. 
At the time Coconut leaf disease attacts attention, 
I noticed fungoid attacks on very many plants, and 
I brought them to Mr. Potter's notice. If I mistake 
not, he took away with him other leaves than Coco- 
nut. The wild bread-fruit, wild-fig, cinnamon, and 
other trees had attacks on the upper surfaces of 
their leaves very like the rust-like spots now to be 
seen on the upper surface of Coconut leaves. Could 
these be the alternating hosts of the Fungus ? Here 
is an interesting study for Mr, Drieberg. — B. — Local 
•• E taminer." 
♦ 
THE BLACKMAN SYSTEM OF WITHERING;. 
(By the " Peripatetic Planter.") 
(From the Indian Planters' Gazette, Oct. 29fch.) 
The following particulars about the Blackman sys- 
tem of withering, which I have gleaned from Mr. 
Skinner of Silcoorie, in an interview, may be of use 
and interest to a good many. At Silcoorie, there is 
more than an ordinary amount of heat developed in 
the manufacturing room below the withering floor ; 
as the Blackmau system has enabled Hm to concen- 
trate the manufacture from outlying ga dens, all at 
Silcoorie. Under these circumstances lets fan-power 
is required than auder ordinary conditions, as tha 
warmer the air, the more absorbent it is, and vice 
versa. Hence, the cooler the air to be employed, the 
more air is required, and consequently the more tan- 
power to supply and remove it, rapidly. The length 
of the Silcoorie house is about 100 feet and the width 
45 feet, there being a lean-to roof over an annex 
the full length ot the house and about 20 feet wide. He 
employs four rows of withering shelves down the whole 
length of the main building and three down the 
annex. The " shelves " are only about 2 feet wide, 
and are those known as Main's being metallic. They 
are about 17 deep iu each row. Hence in each row we 
have 17 x 2 x 100 = 3,400 square feet, or iu the 7 
rows 23,800 bqu^re feet of surface. The method adopted 
is, to place the leaf, when brought in, in a godown 
sometimes a foot or so deep, and draw it from theuce 
as rquired to fill the shelves, and be withered. It 
will surprise a good many to learn that with only this 
23,800 square feet of surface, 150 to 200 waunds of 
green leaf cau be easily withered in the wettest of 
weather in ample time to allow of the rolling and 
firing being all completed, and the tea-hjuse cWed for 
the night at 5 o'clock in the evening, fSx 10 hours 
from starting? The chd bungalow Sihib's lit will 
not be such a bad one in the near future as it 
sometimes has been, it is clear. Mr. Skinner does 
not know what night-work is, save as a nigl t-mare of 
the past. All the fatigue, and harrassment, all the loss 
which is so unavoidable when night work is requirerl, 
are things of the primitive past to him. His fans, 
three in number, are erected equally distaut, in the 
partition between the withering floor of the main- 
building and the lean-to annex. At the opp site side 
of the withering floor to the fan-side, there is a s'it in 
the floor, the whole length of the building. Th« waim 
air from the driers below is sucked up through this 
slit, passes through all 4 rows of withering shelves, 
to the fans, and is blown down into and through the 
tea on the shelves iu the annex, (after parsing through 
the fans,) and then out into the open air through 
the two open ends of the anaex. Just below each fan 
is a shield about 6 feet wide, consisting of small bam- 
boos laid horizontally between the roof of tlio annex 
and the main-wall, the bamboos being 1J to 2 inches 
apart; this shield suffices to distiibute and break the 
direct force ot the blast, so no leaf is blown off the 
shelves immediately below the fans. Mr. Skinner 
prefers this arrangement of the fans, to placing them 
at one end of the building, and drawing the air so far. 
The air has less distance to travt 1, and is consequently 
more even in its absorbing power, as it is not saturated 
en route before it has been made to do all its w ork. 
Further, there is no risk of blowing any leaf off the 
shelves, if the shields are properly erected. With his 
three fans (48-inch) he has found with this compara- 
tively trifling withering surface no difficulty in turning 
out 640,0001b of made tea in a season and could have 
easily done more ! Compare the cost of the upkeep 
of such a small house as is thus required with the up- 
keep of the roofing, &c, required under the old system, 
— and that saving should pay for the fans in one season. 
Then, the gain in quality, bv uniformly successful 
withering in all weathers, and the absence of loss due 
to night work, become sail profit. I am only trying to 
repeat Mr. Skinner's own words as nearly as I cau 
recollect them. He has, as I have said, 3 fans at present, 
but thinks that he could still further hasten matters by 
having a fourth. The fans, he says, to draw across a 
house 45 feet wide, with four rows of obstructing 
shelves en route, will succeed capitally when set not 
more than 20 teet apart, having due regard to the 
important factor, that the coldei the air used, the 
more of it must be pasi-ed over the the leaf. By 
making the only exits for the air, the two ends of 
the annex, the leaf in the annex gets the whole 
benefit of the current, and the air, as it leaves the 
ends of the annex, after doing its work, is still 
absorbent enough to dry wet clothes rapidly. The 
