RUBBER 685 



preparation need not trouble the estate manager whose 

 drying shed is ordinarily effective. Under extraordinary 

 conditions of retardation of drying it is possible for spores 

 to germinate upon the surface, the mycelium ultimately 

 growing into the rubber and causing characteristic spots. 

 But it is unnecessary to isolate spotted rubber from 

 factories in order to prevent the spots spreading from the 

 infected to the clean sheets. However, if the drying 

 shed becomes congested so that the spotted rubber is 

 in contact with the clean, the former ought to be removed 

 to facilitate the drying of the remainder. 



Dilution oj Latex in relation to Spotting. 



Planters assert that there is a great increase of spotted 

 rubber during rainy weather. Experiments were con- 

 ducted to test this view. Rubber samples prepared from 

 latex diluted with varying amounts of tap-water and dis- 

 tilled water always showed a greater tendency to produce 

 spots than samples prepared from undiluted latex. This 

 is not surprising when the facts are taken into considera- 

 tion. 



Evidence has been brought forward to show that 

 undiluted latex is an unfavourable growing medium for 

 fungi. If latex is a good medium the tapping of the 

 tree provides the opportunity required by many fungi to 

 enter the tissues and to cause diseases. If such is the 

 case there would be far more trouble with Diplodia 

 cacaoicola, the common " die-back " on Hevea brasilien- 

 sis, than there is at present. Not only this fungus, but 

 many other " wound parasites " would find their way 

 into the tissues of the tree. Latex diluted with water, 

 however, is probably a much better growing medium. 

 Addition of water to latex means : (i) Closer approxima- 

 tion to a neutral solution; (2) changes and solution of 

 some of the protein materials; (3) quicker development 

 of acidity which up to certain limits increases the chances 

 of germination of the spores. All these factors favour 

 the development of the spores and give the fungi a much 

 better chance of development. 



