Dm 1901.] THE TROPICAL AGRICULTURIST. 
but it must be remembered that the tiale responsible 
for the evil may have been 12, 19,24, o.- even more 
davs previously". The mycelium of the fan^us ia pre- 
sent in the leaf long before the discolouration is per- 
ceptible. In fict, there is no doubt iu some of the 
flush picked and taken to the factory some myceiiom 
of the fungus so that, if these leaves had been left, 
in a few days the disease would have been noticeable. 
The methods of cultivation of tea are most fortu- 
nately the most excellent moans of comb uing l?af 
diseases. The grey blight in nearly allc.ises is ooofiQed 
to the leaf tissues, uoi spreadint; to the leaf stalk, but 
I have iu a few cases found this not to be the case, 
and I have receive 1 specimens from three different 
districts in which the fun-^us has spread to and partially 
killed the leaf stalk and the young woud of the bash. 
This should be looked out for by all planters carefully, 
and directly it is observed the tiush should be piuned 
back below" the discoloured leaf stalks and youug 
branches. If the grey blight began to invade the 
permanent portions of the tea bush it would prove a 
much more serious enemy than it is at present. 
After the grey blight mycelium has grown for some 
time and ijroduce'l a fairly large discoloured patch, 
spores are produced and these becoming detached 
float about in the air and are carried by the wiud to 
other tea and the same process goes on again. 
A most interesting instance of the nature of the wind 
distribution of spores is to be seen quite near to this 
place. There is a belt of jungle aloug the crest of a 
Jiill about 30 yards wide and a ro_d cut throu^ih the 
trees. The tea on the far side of the jungle was 
blighted fairly badly but the tea on the near side — the 
leeward — was only blighted just at the place where the 
wiud blew through the gap in the jungle — -a clear case 
of wind borne spores and a most instructive one. 
With regard to the measures to be taken to reduce or 
avoid the evils caused by Grey Blight, our knov/ledge 
of the life history of this (though this is not yet com- 
plete) shows us the direction in which success is most 
likely to bs gained. The destruction of as many 
diseased leaves as possible remove an immense 
quantity of spores. Burning is the only effective 
means of destruction. Unfortunately men whoiiad taken 
trouble and spent money iu removing their blighted 
tea leaves were discouraged when the effects wore not 
83 markedly beneficial as they hoped. This would 
always bo so while only one man here and there went 
in for preventive measures. Universal co-operation 
in such sanitary means was essential to a complete 
success. 
The study of the factors which are needed for an 
outbreak of grey blight is of importance and it is a 
matter for surprise that after an abnormal prevalence 
of this disease in 1838, followed by two years of 
rather exceptionably favourable weather for the spread 
of fungi, the quantity of grey blight is less than be- 
fore. What factor is missing is not known. It is prob- 
able that the distribution of spores by the wind 
has been in some way favourable — perhaps a larger 
quantity has been carried av;ay from the areas of tea 
cultivation than at other times. 
The other diseases of the leaf in tea common in Cey- 
lon are CoUetotrichum camellice and ClaJo'poriinn her- 
hai-tiin. The former was observed in 1897, and sent 
home to a mycologist, Mr Massee, at Kaw and 
named. I had not seen it on any tea in Oaylon until 
some months ago I got it from the same estate as it 
was got from before, so that in the four years inter- 
vening it has not spread, and therefore need not be 
considered as a serious danger. Clad osporium is also 
comparatively rare. 
Turning to root diseases, for I am thankful to say 
we have no stem diseases, there is a disease which 
must be watched for and guarded against as carefully 
as possible. It is known to science as llossdUnia 
radicijjerda, and is characterised by a white thread 
like myoalium which can easily be seen with the naked 
eye. The majority of fungi are either s iprophytic i.e. 
living on dead and decaying substances, or parasitic, 
i.e., preying on living animals or plants, but in thia 
case of Rossellhna the fungus starts as ft saprophyte 
on any dead limber, roots especially, and spreads to 
the living roots of tea and other plants. The v/hite 
threads of mycelium can stretch out 710 iuchts from 
the dead root on which they are growing until they 
reach the yonng and tender rootlets of the growing tea 
bush. Those roots of jungle trees like Siiuplocos which 
are soft and spoogv in tissue afford the best home for 
the fungus and enable it to spread more luxuriantly. 
In connection with this I have been working for some 
little time lately upon a disease of Gtevilleas which 
may be due to the savager of this same root disease 
I have not yet discovered whether the root disease. 
[liosselliaia) is the cause of the death of the Grevilieas, 
or whether it comes on the dead roots of that tree 
after the tree is killed. I am experimeut'ag by infec- 
ing the roots of a Grevillea tree with the fungus to see 
if it is capable of killing the tree. However it is im- 
portant for every planter to recognise that the Grevillea 
roots may be the harbourers of this dangerous disease, 
and when they have a tree dying or dead to use 
preveuuve means. The best preventive means for this 
and other root diseases is to isolate the diseased tree 
or trees by means of a trench one foot wide, and a^ 
least two feet deep, over which the mycelium of the 
fungus cannot stresch— in addition lime should be put 
into the affected patch and all diseased roots should 
be taken out and burnt. If this is not done the roots 
of supplies will contract the disease, sometimes three 
or four supplies dying in the same way and from the 
same cause. Buried pruniogs also where this root 
disease existed are a source of danger as the fungas 
could start there on a piece of buried pruniugs not 
thicker than a pencil. In affected spots it is best not 
to bury prunings «t all and in pla ^es where from damp 
or adjacency to infected places danger is feared lima 
should be freely used with the prunings. Damp and 
nudrH.ined spots were the most likely to be the starting 
points of thia evil, and the cutting of the isolating 
trenches would tend to reduce his condition. 
" BKACKBN FEKN AS LITTER." 
Under this hearting the following paragraph 
appears in The Field, of the Idth ultimo : — 
Mr J Hughes f.i.c-, refers to the manurial value 
which the dung-heap supplies to the land where 
this fern is used, but it is not generally known that 
the animals which are littered with it are believed 
to be sale from the attacks of insect pests. Th« 
South Cheshire Fo.Khounda (the bitch pack) 
have for many years had no other litter in their 
kennels and the late kennel huntsman informed me 
that neither the puppies nor the working pack ever 
were troubled with insect parasites of any kind 
and to all appearance it was inimical to lice, fleas' 
and all other insect^. It was believed that the fine 
condition of skin and coat which these hounds 
always possess must be attributable to its use. The 
late master has a large stretch of wood some six 
or seven miles from the kennels, where the bracken 
grows in great profusion and is cut down and 
stacked like hay every summer being carted to the 
kennels in great trusses as required. — W.G. 
- — ■———«»-' ' " -i 
" CACA.O AND Criticism." — Under this 
heading a practical c-icao planter delis^ers 
himself in reference to recent writings and 
criticism in general. It is, as he points out, 
comparatively easy to find fault with Com- 
mittees and Scientists : the great matter is 
to lend a hand and endeavour to work for 
the common good, hy making further use- 
ful suggestions, or additions to the questions 
•which have been circulated. 
