164 Ustiilina Zonata [Lev.) Sacc. on Hevea Brasilieiisis 



wood was well marked by a diffuse brown discoloration, and after twenty- 

 four hours in the Laboratory, a copious white mycelium appeared at this 

 junction. Pieces of this myceUum used to inoculate flask cultures of 

 potato agar gave rise to cultures which, except for the absence of zoning, 

 corresponded to those obtained from the collar-rot caused by Uslulina 

 zonata. 



Other cultures were started by placing small portions of the black 

 lines developed in the rotten portions of the wood in sterile damp cham- 

 bers. In two days hyphae began to grow out; after four days the small 

 pieces of diseased tissue with the attached mycelium were taken and 

 placed in flask cultures; similar non-zoned cultures to the ones described 

 were ultimately obtained. 



The boreholes made by the insects through the rotten wood were 

 filled with fungus mycelium. Small portions were taken to inoculate 

 other flasks and again non-zoned cultures resulted. 



The non-zoned cultures are characterised by a peculiar folding of the 

 crust which forms on the surface, due to unequal growth in different 

 directions. This folding is seen especially well when the culture medium 

 is rather soft; when hard the folds radiate out from the centre in a more 

 or less even manner. 



CULTURES FROM SCORCHED TREES. 



Stems of the trees attacked by borers, from estates which were 

 troubled with leaf fires, were taken to the Laboratory and the fungus 

 isolated from them. Specimens from two estates were treated and 

 typical non-zoned cultures were obtained starting from small pieces of 

 the black lines. 



CULTURES FROM CONIDIA AND ASCOSPORES. 



From another estate which suffered similar damage owing to a leaf 

 fire a rubber log was obtained carrying a large fructification twelve inches 

 long and four inches broad on the stem. Over the greater portion of the 

 surface the smooth conidial layer was present. After two days in the 

 Laboratory the ascospores began to be extruded from the perithecia over 

 about one square inch of the stroma. Cultures were obtained from the 

 ascospores by setting a few of these in flask cultures. Non-zoned cultures 

 resulted. 



Cultures are difficult to start from conidia. Numerous foreign spores 

 fall on the flat fructifications, and these develop more quickly in cultures 

 than those of Ustulina zonata, with the result that the latter is crowded 



