RUBBER 195 



East Indies is frequently followed by Botryodiplodia 

 elasticae which may become very destructive. Alte- 

 naria castilloae, Zimm., and Capnodium javanicum, 

 Zimm., have both been reported from the Dutch East 

 Indies, but the latter is doubtless saprophytic on the 

 secretions of insects. 



Root Diseases. Fomes semitostus, Berk., is a fungus 

 which attacks Hevea braziliensis and other trees, causing 

 a root disease which has proved very destructive, in 

 some cases destroying as much as 40 per cent of 

 the trees of the Malay States, Ceylon, and Straits Settle- 

 ments. The roots of the dead trees become covered 

 with white or straw-coloured masses of mycelium which 

 also penetrate the soil and may pass from tree to tree. 

 If the dead tree or stump be protected by a vine or 

 other dense plant growth, the fructifications will be 

 produced in the form of hoof-shaped or bracket fungi. 

 These fruiting bodies are frequently four to six inches 

 across. The upper surface is a dirty yellow or buff 

 colour, which may be orange or maroon in the older 

 parts. R is covered with a delicate map and marked 

 with concentric, shallow grooves. The lower surface is 

 orange-coloured when young, shading into brown as it 

 grows older. It is filled with numerous very small pits 

 which can be distinguished only by aid of a hand lens. 

 Within these pores the spores are produced. Although 

 parasitic the fungus will persist on the dead trees as a 

 saprophyte. 



The only satisfactory remedy that can be recom- 

 mended is the complete destruction of the diseased trees 

 by digging and burning. However, it is possible that 

 trees may be protected to some extent by digging 

 trenches about two feet in depth around the healthy 

 trees, which are close to infected areas, and putting 

 a considerable quantity of lime in the trenches. This 

 precaution may serve to prevent infection through the 

 soil, but would not interfere with many insects and 

 animals which may carry the organism from the diseased 

 or dead trees to the healthy ones. 



