510 XOTK OX POLYPORUS LUCIDUS LEYSS. 



were arrested I am not at this stage in a position to sa>-, hut it 

 is not unlikely. 



On the upper surface of the mature sporophore there are 

 usually spores resembling in colour, size, etc., the ordinary spores 

 of the fungus. I have not seen any of these spores attached, 

 and hence can only look- upon them as Conidia with a certain 

 amount of doubt. 



These conidial spores are also found in Fames apfilaiiatus 

 Pers. and other Polyporacese. 



How THE FUXGUS GAINS ENTRANCE INTO ITS HoST. 



As often as not the fructifications are formed near the 

 .uround (observed in Acacia, Salix, Ziz\\phus), and this would 

 suggest that usually an entrance is obtained near the ground 

 level. 



Though there is thus far no direct evidence, it must be held 

 that it is primarily through wounds and abrasions at or near the 

 soil level that the fungus gains entrance, and as is general in 

 fungoid diseases, trees wdiose vitality has been diminished 

 through external conditions would be more suscej^tible than 

 young actively growing trees. 



It has been observed that usiially the afifected trees are on 

 low grotmd, a situation which, owing to the usual i^resencc of 

 moisture, would be a favourable factor for the external growth 

 of the hyphse of the fungus. As observed on Salix and Acacia 

 around Pretoria, these trees were in the vicinity of watercourses, 

 though elsewhere I have found the fungus where there was no 

 watercourse in the immediate vicinity. 



I would reuard the fungus as a facultative parasite which 

 is rmly likcl\' to Ijecome established when the ability of the trees 

 to re.sist its attack is impaired by unfavoural)le conditions. 



Patiioi,o(;i( AL Anatomy t)F Willow infected with 



POLYPORUS LUCinUS. 



It was originally intended to compare the jjathological 

 anatomy of Salix and Acacia infected with this fungus, but 

 owing to difficulties in obtaining material of Acacia, I have for 

 the jfresent to limit my.self to a description of Salix. 



Stevens* mentions Pomes Incidns as causing cocoanut root 

 rot. ])ut I have not been able to gain access to any work on the 

 fungus cither in relation to cocoanut root rot or disease in other 

 trees. 



The general naked-eye appearance of the disease is the white 

 mottled spots in the wood. In tangential sections these areas 

 are seen to run at about right angles to the grain of the wood, 

 and also to extend upwards and downwards along the stem, i.e., 

 in the wood elements. Plate i6, h and c, are photograi)hs of 

 diseased wood of Salix and Acacia respectively. 



* .Stevens. F. T.. : "The Fungi whicli cause Plant Diseases," (1913), 



I 



