127 



By careful observation it will be noticed that the discoloration 

 more often appears on the under side of the leaflet first, but the 

 pale yellow, and later the greyish discoloured areas, are equally 

 evident on both surfaces. This is due to the disappearance of the 

 chlorophyll or leaf green, and the subsequent death of the cells 

 comprising the tissue of the leaflet, as the diseased areas are gene- 

 rally sunken through being thinner than the healthy portions. 



It would appear that the tips of the distal leaflets show the 

 effects of the disease first, although an examination of an affected 

 leaflet shows that diseased areas are scattered all over its surface. 

 From these distal leaflets, the disease appears to spread gradually 

 to those nearer the stem, and often when all the leaflets on the 

 terminal 2-3 feet of the leaf have been attacked and appear in a 

 dry, withered condition, this portion of the leaf breaks down, if 

 the leaf happens to be floating in the air in a position between 

 the vertically upright and the horizontal. This end of the leaflet 

 rarely falls to the ground, but remains hanging to the healthier 

 postion, and is very characteristic of the disease. 



If, however, the leaf is older before it is attacked i.e. hanging 

 between the horizontal and the trunk of the tree, the tip does 

 not often break. This shows that the breaking of the tip of the 

 leaves is due to the weight of the diseased portion itself and is, 

 therefore, due to natural causes. Many trees were examined that 

 showed leaves with their tips broken off and hanging down in 

 this manner and all showed that they had disease spots distributed 

 throughout their leaflets. 



The yellowish spots that are characteristic of the disease in 

 such cases are found in the greatest abundance on the distal leaf- 

 lets but eventually all the leaflets become attacked. 



After a time, when a large number of disease spots have made 

 their appearance, the whole leaf assumes a yellowish appearance 

 and gradually becomes greyish and withered. This may remain 

 hanging to the trunk for a considerable time but finally it drops. 

 In the early^ stages of the disease, only a single leaf may be at- 

 tacked, but usually several are noticed on every diseased tree. 

 As a result of the diseased condition of the leaves, the number of 

 nuts borne on the later-developed flower-stalks diminishes, and 

 finally no flowers set. When a large number of the leaves have 

 been badly attacked the terminal bud is left standing alone, and 

 it is only a question of time before this falls over, and the death 

 of the palm results. 



Close examination on the upper surface of the leaf of one of the 

 disease spots when it has assumed the grey colour, shows minute 

 warts, not larger than the head of a small pin. They are black- 

 ish-grey in colour, and are irregularly distributed, often being 

 very numerous. They are more or less oval in shape and suggest 

 that the upper cuticle of the leaf has been raised. This can be 

 shewn to be so, for if a diseased leaf that has fallen on the 

 ground where sufficient moisture is present,be examined, it will be 

 observed that these small postules rupture, usually by a triangular 

 slit, through which a greyish powder protrudes. 



