310 DISEASES OF CROP-PLANTS 



grew less intense from without inwards. These observations 

 presumably indicate the course of the infection. 



Infection. 



According to the experiments made in India the fungus 

 cannot penetrate the unbroken rind of the internodes, but can 

 enter by way of wounds, leaf scars, or the root eyes of the nodes. 

 Cuttings were also experimentally infected by dipping them 

 before planting in water containing spores and mycelium of the 

 fungus. It is further reported from India that the infection so 

 far as it has been followed is not virulent ; spread within the 

 cane is gradual and communication from one plant to another 

 slow. A large number of borer holes become infected late in the 

 season, but the parasite usually remains confined to a few inter- 

 nodes. Leaves have been artificially infected with the fungus, 

 but it has not been found occurring upon them in the field. 



J. S. Dash carried out inoculation experiments in Barbados 

 and found that in healthy canes the fungus was only weakly 

 parasitic and made slow progress beyond the point of infection. 



The point of greatest interest in connection with the presence 

 of this disease in the West Indies is that under certain circum- 

 stances it can produce effects similar in their nature to those of 

 red-rot in varieties which are regarded as practically immune 

 from the latter disease, and may thus to some extent account 

 for reports of their occasional infestation. 



Control. 



No general measures are at present called for in respect of 

 the disease on West Indian canes, which would seem to be more 

 resistant than those of India. Should it become more serious 

 it will be necessary to avoid suspected stools as sources of material 

 for planting and to reject cuttings showing red discoloration. 



Top-Rot (Bud-Rot) 



In the year 1895 an affection to which the name top-rot was 

 given began to assume epidemic form in Java. It had previously 

 been known only through sporadic cases. At an earlier date a 

 disease with similar characteristics had been described from 

 Australia under the name of gum disease. Cases have occurred 

 from time to time in the West Indies which have had somewhat 

 similar general symptoms and have been described under this 

 name. 



The Javan disease consists essentially in the failure of the 

 terminal joints of the cane ; the leaves attached to the growing 

 point may remain normal, or degenerate into a pulp, while the 

 interior of the nodes immediately below it becomes involved in a 

 sort of soft rot, producing a glassy appearance of the tissue and 



