234 



In the vast majority of cases, however, another disease 

 was concerned, which has of late years received the 

 name of „die-back disease", and which, after a preliminary 

 investigation, was found to be caused by Chaetodiplodia. ') 



Symptoms of the Disease. 



The disease is especially destructive in fields, where the 

 trees, for some reason or other, are leafless or hâve only 

 a thin foliage. Such a condition is often brought about 

 by successive attacks of witches'brooms, by repeated 

 shedding of the leaves in attacks by Thrips, by the 

 eating of the leaves by ants or by the sudden exposure 

 of the trees to sun and wind. In short, trees in such a 

 state of complète or almost complète leaflessness, are the 

 first to be attacked by the die-back disease. We never 

 noticed the disease on healthy leafy branches. 



There is an obvions différence between trees killed by 

 canker {Spicaria colorans) or by worms (larvae of Steirastoma 

 depressimi) and trees which are suffering from the die-back 

 disease; in the former cases the leaves generally dry up 

 and in this condition they remain hanging on the dead 

 tree, a resuit of the rapidly fatal course of thèse diseases; 

 in the die-back disease on the other hand the leaves while 

 still attached to the tree, first assume a yellow and 

 sickly appearance and then they fall off, so that the tree 

 has already lost ail its leaves before it is quite dead. 



Generally the disease first shows itsolf at the top of the 

 twigs which hâve borne witches'brooms, or hâve sufFered 

 from Thrips or other adverse influences. Thence the 



1) C. J. .J. van Hall and A. W. D r o s t. Recueil des Travaux 

 botani(|ues néerlandais Vol. IV. 1908. p. '288. 

 Département van Laudbouvv in Surinaïue. Bulletin no. 16. p. 41. 



