245 
fungus had b:en commenced before my departure from England and 
were practically completed by the end of the year, the establishment 
of the identity between this fungus and the “die-back” fungus on 
cacao in other parts of the tropics has been made, and a fairly 
accurate knowledge of its life-history has been obtained. A preli- 
minary note on these points was issued in the Agricultural Bulletin 
of December, 1910. 
An account of a bacterial disease of potato and tomato was 
published in the same issue of the Agricultural Bulletin. 
Greater attention has been paid to the diseases of Hevea brasi- 
Mensis than to those of other plants. To review the diseases of this 
plant from a general aspect, it may justly be said that the plant com- 
pares most favourably with the staple plant industries of other 
tropical countries. It must, however, be admitted that the continued 
cultivation of one plant in pure culture over large areas, without the 
intervention of other crops or, in many cases, of belts of natural jungle, 
lends itself somewhat readily to the development and spread of 
fungus disease. It should not, therefore, be surprising if there were 
an increase of its parasitic fungi, both in quantity and in number; 
this will call for the application of methods of treatment other than 
those which are employed at the present day. 
Some danger may arise both from the importation of pests and 
from the absence of proper treatment of disease in native cultivations. 
DISEASES OF PARA RUBBER. 
Root Diseases. — Fomes semitostus, Berk., appears to be more 
prevalent in this country than in Ceylon. The amount of the fungus 
which is present on young clearings is directly proportional to the 
amount which is present in the original jungle. The fungus, there- 
fore, continues to make its presence felt among younger rubber, 
where a death-rate of as many as 16 per cent, of the trees has been 
recorded in 18 months. Consequent upon the removal of timber, the 
isolation of diseased areas by a system of trenches, ^he removal of 
trees which have succumbed, the digging over and subsequent liming 
of diseased areas, the fungus gradually disappears as the rubber 
grows older, until on those estates where careful treatment has been 
practised it is practically absent among the older rubber. The rate 
of spread of the fungus mycelium in the soil is directly proportional 
to the water-content ot the soil or, in other words, to its capacity for 
drainage. Whereas on the lighter soils there is no appreciable spread 
of mycelium independently of actual contact with roots, on the lowly- 
ing, damp, heavy and badly drained soils an independent spread of 
the mycelium occurs, and the rate of growth, and consequent period 
of retention of the fungus by the soil, are much increased. This is a 
factor which has not hitherto been brought to light and which should 
be borne in mind in the opening up of land for planting and in the 
drainage and removal of timber of the heavy, lowlying soils. The 
