172 Ustulina Zoiiata {Lev.) Save, on Hevea Brassilieiisis 



escape attacks by Ustulina zonata. This fungus appears likely to cause 

 damage on most old properties. 



(6) Plantations thinning-out with trees not yet ten years old. 



Estates about to thin out from which no jungle stumps have been 

 removed or timber cleared, should attempt to follow the advice given 

 under (a). On all estates the method of thinning-out should follow the 

 same lines as treatment advised for clearing land at the beginning. One 

 tree should be cut, and the stump, lateral roots and logs removed and 

 destroyed immediately. A sharp watch should be kept over the thinned 

 area for signs of borer attacks on standing trees and those attacked should 

 be cut out and destroyed quickly. This treatment prevents the multipli- 

 cation of boring beetles by destroying their breeding grounds. 



PERIOD AFTER TREES ARE TEN YEARS OLD. 



On most old plantations in Malaya, this disease will be found to be 

 responsible for the death of numerous trees. In a previous publication (lO) 

 the writer stated that it might be possible to treat old trees attacked at 

 the collar by cutting out the diseased tissues and running a pillar of 

 concrete up the middle. Since then, this method has been tried, but from 

 the planters' point of view is unsatisfactory because of the expense. 

 Therefore, if diseased trees are found in an advanced state of decay, they 

 should be cut out immediately, care being taken to remove all diseased 

 laterals to prevent contact infection. The greatest damage on old planta- 

 tions arises from infection of roots of healthy trees by contact with 

 diseased laterals of neighbouring trees ; the recognition of this fact must 

 not lead to a minimisation of the dangers of spore infection. 



Fructifications are common on the surface of the diseased tissues at 

 the collar. They develop quickly, so a constant watch should be kept on 

 attacked trees, if left standing. Two examinations a week would be 

 advisable, and immediately fructifications are observed, a tin of kerosene 

 oil should be obtained and the fruit-body gathered and immersed in the 

 oil. This will help to prevent the spread of the fungus about the plan- 

 tation by means of wind-borne spores. Wounded lateral roots on trees 

 over six years old showing above the surface of the soil are convenient 

 places of entry for the fungus. Such roots showing black lines below the 

 wounds should be cut off if they can be spared. 



Many managers see difficulties in the amount of burning which is 

 required. Burning, however, is carried out successfully all the year round 

 on many estates in the treatment of " Pink Disease," with little damage 

 to the permanent trees. 



