RUBBER 6OI 



As to the circumstances in which the fungus is able 

 to enter the stem there is some difference of opinion. 

 Bancroft, as a result of his experiments, concludes that 

 it is simply a wound parasite, i.e., that it can enter 

 through any wound, or, at least, one which exposes the 

 wood. His experience in Malaya differs from that in 

 Ceylon, in that dieback has been found to begin there 

 from the stubs of pruned branches. In Ceylon that has 

 not yet been observed, though pruning has on many 

 estates been carried out on an extensive scale. And 

 attempts to infect healthy Hevea saplings, i or 2 years 

 old, with the spores of Botryodiplodia have failed. The 

 most remarkable fact, however, which tells against the 

 theory that the fungus is a simple wound parasite is that 

 it has not yet been found to attack the tapped surface, 

 even though the wood has been exposed by bad tapping. 



It is noteworthy that Botryodiplodia theobromse follows 

 soon after the attack of another fungus in many cases, 

 and it is because of that faculty that so many diseases 

 have been attributed to it. It develops rapidly on Hevea 

 pods, or Hevea cortex, previously attacked by Phyto- 

 phthora Faberi, and it similarly follows pod disease and 

 canker of cocoa. Observations in Ceylon would seem to 

 indicate that, in general, Botryodiplodia follows a previous 

 fungus attack, and that in tKe case of dieback of Hevea it 

 obtains an entrance through dead green shoots. 



The green shoots of Hevea frequently die, and this 

 effect may be produced by several agencies. Wind, over- 

 tapping, shade, or excessive rainfall account for it in 

 some cases, while it may be brought about also by a 

 definite fungus attack, as by Gloeosporium alborubrum, 

 Phyllosticta ramicola, or the canker fungus, Phyto- 

 phthora Faberi, following an attack of pod disease. So 

 long as the green shoots only are concerned this effect 

 is negligible, but it may be followed by an attack of 

 Botryodiplodia theobromse, which kills the tree. Observa- 

 tions in Ceylon would appear to show that when the 

 Botryodiplodia attacks the tree the green shoots have 

 been previously killed by Gloeosporium. 



The abundant development of Botryodiplodia on felled 

 Hevea stems provides a reason for burning all Hevea 



