RUBBER 695 



per acre, selection methods are now being adopted in 

 new clearings. By tapping and testing individual trees 

 over large areas, a few which give a very high yield of 

 latex and rubber are selected, and these are broken up 

 into cuttings from which new clearings are planted. The 

 tree grows readily from cuttings if care is taken in plant- 

 ing them. Several clearings have now been established 

 in this way, and it is intended to select the best trees in 

 these and plant further areas with cuttings from them, 

 and it is hoped that in this way the yield per acre may be 

 materially increased in the future. At the same time the 

 possibility of seed selection and the breeding of hybrids 

 with increased latex content has not been lost sight of. 



Manurial experiments are in their infancy, and Ceara 

 has not been treated seriously over a long enough period 

 as yet for any reliable figures to have been obtained. 



In 1909 Mr. Wilcox, the Special Agent in charge of 

 the Hawaii Experiment Station, published an account of 

 some experiments he had conducted which showed that 

 nitrate of soda had a decided tendency to increase the 

 flow of latex. We repeated his experiments on a small 

 scale with nitrate of soda in 1911, and on a larger scale 

 with nitrate of soda and nitrate of potash in 1912, with 

 the result that Mr. Wilcox' s results were confirmed. 

 Nitrate of soda applied just before tapping begins un- 

 doubtedly does increase the latex flow and rubber yield 

 of trees which do not normally yield well, while nitrate 

 of potash apparently still further increases this flow. 

 Over areas which normally yield well, however, no 

 improvements could be obtained from the application of 

 these salts. The experiment is still being continued, and 

 perhaps it is too early as yet to say more about the 

 results obtained. 



The diseases of Ceara in Southern India are few and 

 comparatively trivial. The most important is a root 

 disease due probably to the fungus Hymvnochsete noxia, 

 which also attacks Hevea rubber, coffee, tea, and a 

 number of other plants in India. This disease is con- 

 trolled by removing as many jungle stumps as possible 

 from the clearings and ridding the soil of decaying wood 

 on which the fungus can live, and by means of which it 



