F. T. Brooks 213 



the stumps of old forest trees are so large and so resistant to decay 

 that it is very expensive to remove them. Where, however, stumping 

 can be carried out at a low figure before the estate comes into bearing 

 the operation insures against serious attacks of root disease and facilitates 

 the movements of coolies engaged in weeding and tapping. If the cost 

 of clearing the timber is high, and Fomes does not threaten seriously, 

 the cheapest course will probably be to treat root disease as it appears. 



Even on estates which are apparently equally encumbered with 

 timber the prevalence of Fomes varies greatly. Some plantations are 

 seriously troubled by it in the early years, others are never much affected. 

 Soils which are either very loose or clayey seem to favour the disease, 

 soils of an intermediate character being less liable to it. The underground 

 strands of the fungus are sometimes found at a depth of two and a half 

 feet in loose soils but usually they are not more than 18 inches below 

 the surface. 



As Petch(iO) points out, trees that are invaded by white ants have 

 generally been previously attacked by Fomes lignosus. When such 

 trees have been blown over, examination often fails to reveal signs 

 of the fungus which together with much of the diseased wood has been 

 consumed by the termites. 



Even though the stumps and underground timber are not removed 

 after planting, most estates which are properly managed become 

 practically free from Fomes as they become older. This is due to the 

 preference shown by Fomes lignosus for living upon timber in the early 

 stages of decay ; as the wood becomes more and more rotten there 

 s less likelihood of Fomes growing upon it. Fomes lignosus com- 

 paratively rarely attacks old rubber trees and the death of many old 

 trees attributed to it is likely to have been really caused by Ustulina 

 zonula as described by the writer (5) elsewhere, or by Sphaerostilbe 

 re-pens as will be pointed out later in this paper. 



With the general decrease of this disease the fructifications of the 

 fungus are now more rarely seen. The growth of lalang grass in badly 

 kept estates appears to favour the development of fructifications at 

 the base of diseased rubber trees, and upon one low-lying estate seen by 

 me the fruit bodies were produced in abundance along the sides of the 

 drains. 



A large number of fructifications were examined by the writer at 

 different times of the year and the large majority of them were found 

 to be sterile. Sections of fructifications which were apparently mature 

 repeatedly failed to show functional basidia. I never succeeded in 



