DISEASES OF COCONUT 185 



when trees are suffering from drought, water-logging, or any 

 cause which affects the ability of the tree to nourish the full 

 number of fruits set. Injury to the base of the spikes such as 

 may be caused by insects or by careless picking will also cause 

 young nuts to drop. 



Another early sign of the disease is the discoloration of 

 the flower spikes, which turn chocolate brown and eventually 

 blacken and wither. Investigation at this time reveals a dark- 

 coloured wet rot about the base of the affected parts. The 

 rot works its way through or under the moist strainer, affecting 

 the leaves or inflorescences as it reaches their points of attach- 

 ment. Water-soaked areas appear on the leaf stalks, and as 

 the rot progresses the leaves involved turn jellow and hang 

 down. On the relatively hard tissues of the leaf base the rot 

 does not penetrate far below the surface and if the spots become 

 exposed to the air they dry up. The softer tissues adjacent to 

 the bud are much more easily penetrated and when the infection 

 reaches the central column they become entirely in^■olved in a 

 soft rot which gives off a particularly offensive odour. 



Causation. 



Apart from the type recently separated in Jamaica, in- 

 vestigators of bud-rot in the Western Tropics have so far agreed 

 in reporting the association of bacteria with the disease from its 

 earliest stages. It has not been possible, however, to correlate 

 the findings of the different workers in respect to the species of 

 bacterium regarded as its probable cause. J. R. Johnston 

 reached the conclusion that a species indistinguishable from 

 Bacillus coli was causative, but unfortunately his inoculation 

 experiments were confined to young plants under glass in Wash- 

 ington, in which, moreover, infectipns were only obtained through 

 holes made with an auger. Reinking in the Philippines isolated 

 what appears to be the same organism, and with this and with 

 B. coli from animals found that infections of seedling palms 

 could be obtained through wounds made in the growing point, 

 but only in case of severe injury or excessive dampness. He no 

 longer regards bacteria as the cause of the epidemic disease in 

 those islands. Rorer in Trinidad mentions having obtained with 

 an unidentified but different bacterium typical infections through 

 wounds and also by pouring material from a culture among the 

 leaves of an unwounded tree. 



Control. 



The experience of Jamaica and Trinidad demonstrates that 

 when supported by powers of legal compulsion and carried out 

 under eflective supervision, a vigorous policy of cutting down 

 and burning the tops of all infected trees, with periodical in- 

 spections for the detection of fresh cases, can quickly reduce the 

 incidence of the disease from serious to insignificant proportions. 



