w. mcrAe 225 



These figures give an idea of the extent of cultivation, of the conditions 

 in which Hevea grows, of the range of age of the trees, and, seeing that the 

 disease is present in most of the area, of the amount of each age affected. 



Early notice of the disease. During the increased activity of planting in 

 1909-1910 there was a large demand for seed, and this was partly met from the 

 existing seed on the older estates. In this way the attention of planters was 

 directed to the fact that fruits were becoming attacked by a disease by which 

 they rotted on the trees. Then, too, it was noticed on these estates that there 

 was a considerable shedding of leaves during the monsoon in addition to the 

 normal leaf-fall in the dry weather, but when the demand for seed subsided, 

 less attention was paid to these phenomena. About 1913, however, when 

 efforts were being made to utilize the seeds of Hevea for purposes other than 

 planting, attention was again directed to the tmit-rot. Still it was not thought 

 of much consequence, as the demand for seed for planting had become small, 

 compared to the available supply, and the utilization of seed for other purposes 

 had not yet become a commercial proposition, or at least it had not been 

 undertaken to any extent. About the same time it was noticed on the oldest 

 estates that the leaves fell in increasing nmnbers during the heavy weather 

 of the monsoon, and this was thought to be a result of the exceedingly moist 

 monsoon conditions and to be a partial explanation of the somewhat dis- 

 appointing latex yields which were lower than had been anticipated. This 

 led later on to an investigation, an accomit of which is published in this 

 paper. 



Hevea sheds its leaves periodically in December- January, and all or nearly 

 all the leaves fall then. Up to about the fourth or fifth year from planting, 

 however, yomig Hevea trees do not show this phenomenon to any marked extent, 

 and during these two months yomig plantations are evergreen. Sometimes 

 the leaves are shed before the new flush appears and the trees are comparatively 

 or quite bare, but some trees retain a considerable part of their fohage till the 

 new flush of leaves is well expanded. Thus the " picture of repose " on an 

 estate during the season of leaf-fall is by no means uniform. The leaves 

 assume various tints of yellow, brown, and red, and the whole phenomenon ia 

 comparable to the wintering of deciduous trees in temperate regions. A 

 description of the second leaf-fall that occurs in the monsoon (Jime to August) 

 is to be found on page 227. 



During 1915 a considerable amomit of information was gained about the 

 disease, and it seemed that the fruit-rot, the abnormal leaf-fall during the 

 monsoon, and a rot of the tapped surface that occurred in the latter half of the 



