COLLETOTRICHUM LUXIFICUM, Van Hall 



AND DROST. 

 (Witches' Broom of Cacao). 



This disease was reported from Surinam in 1898 ; in 

 1906 it was observed in Demerara. 



When a tree is attacked by the fungus hypertrophied 

 shoots are produced in bunches, the whole structure 

 assuming the appearance of a witches' broom. These 

 branches are enlarged, show a tendency to grow vertically 

 and have well-marked longitudinal furrows at their basal 

 end. Finally, the whole structure thus formed dies. The 

 inflorescence is frequently attacked, with the result that 

 a dense mass of flowers is produced owing to the branching 

 of many of the pedicels ; the flowers are usually abortive. 



The fungus has been shown to be capable of infecting 

 the fruits directly ; such fruits as are attacked show a 

 hardening of the shell, swelling of the fruit-stalk and 

 blackening of the infected area. Diseased pods seldom 

 mature. 



Diagnosis : — Stromata isolated, forming small masses of 

 a dirty white or sometimes of a rose colour ; conidia 

 continuous, hyaline, slightly constricted at the middle, 

 13-19 by 4-5 microns, usually with a very refringent region 

 in the centre ; setae multiseptate, black or fuscous, 50-120 

 by 3"5~4"S microns. 



HALL AND DROST : Recueil des Trav. Bot. Neerl., Soc. 

 Bot. Neerl., Vol. IV., p. 243, 1908. 



MASSEE: Kew Bulletin, No. 5, 1909. 



Howard : West Lnd. Bull., Vol. II., p. 205. 



Colletotrichum Cradivickii, Bancroft, has been recently 

 found on pods of cacao from Jamaica and is considered to 

 be a new species. The pods had been killed when in a 

 young condition, and their shells were rendered exceedingly 

 hard. 



Diagnosis : — Acervuli erumpent, yellow at first, becoming 

 later pink in colour ; conidiophores hyaline, length at 

 least greater than that of the conidium ; conidia hyaline, 

 pinkish in mass, elongated, with a constriction at the middle, 

 14-17 by 5 microns ; setae straight, rigid, tapering to a point, 

 2-3-septate, purple, 70-100 microns long by 4-6 microns 

 broad. 



BANCROFT: West lnd. Bull., Vol. X., No. 5, 1910. 



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