RUBBER PLANTING 187 



which the roots of the dead tree occupied should be dug 

 over and quicklime forked in, but the elaborate pre- 

 cautions recommended in the case of Fames do not 

 appear to be necessary, as the fungus seldom spreads 

 after the source of infection has been removed. 



On the other hand, if Sphaerostilbe makes its appear- 

 ance, the treatment recommended for Fames should be 

 carefully carried out, since this fungus, too, is able to 

 spread through the soil to adjacent trees by means of a 

 free-growing mycelium. 



Diseases of the Stem Canker. 



Three diseases of the stem are more or less prevalent 

 in Hevea, whilst four others which at present appear 

 to be of minor importance have been recorded from 

 time to time. 



Probably the most serious of the stem diseases is the 

 so-called canker, which has recently been shown to be 

 due to the attacks of the fungus Phytophthora Faberi, 

 and is therefore a near relative of the deadly potato 

 disease. Like the potato disease, the canker of rubber 

 is disseminated by motile spores, which swim actively in 

 the film of water which may cover the surface of the 

 trunk in wet weather. The canker of rubber has been 

 shown to be identical with that of cacao, and the same 

 fungus attacks the fruits as well as the bark in both 

 species. The term canker is a singularly unsuitable one 

 for this disease,' which gives rise to no roughness or 



