146 PARA RUBBER. 



pagation be thereby ensured. The larger their food supply , the quick- 

 er they will increase in number and ultimately prove more serious 

 to the crop on which they are living. On these grounds the conten- 

 tion of Colombo friends " that the cultivation of Para rubber to the 

 exclusion of other kinds of rubber is a dangerous system," has pro- 

 bably much to recommend it. On some large estates the Para 

 trees are being grouped, and each group is separated from its neigh- 

 bour by a belt of forest or of Castilloa elastica trees. Such a belt 

 would prevent, to a certain extent, the spread of disease, and would 

 allow one to more easily combat insect or fungus pests, as soon as 

 they made their appearance on the enclosed Para rubber trees. 



In any case it is well to realize that trees of Para rubber, whether 

 growing under unhealthy or perfect conditions, are not immune 

 from the attacks of parasitic fungi and insects, even at a time when 

 the number and age of the host plants may seem to be almost neg- 

 ligible. The best advice which can be given is to attack all diseases 

 in their earliest stages before the parasites have increased beyond easy 

 control. It is fortunate that among the thirty odd diseases or 

 pests mentioned below none are of a very serious nature, but 

 they are nevertheless worthy of full consideration. 



Para Rubber Pests in Brazil and Java. 



Hennings* has described and figured five leaf fungi, viz., Phylla- 

 chora Huberi, Dothidella Ulei, Aposphaeria Ulei, Ophiobolos He- 

 vese, and Parodiella Melioloides. These have been found in Brazil, 

 but do not seem to be very serious, though the Ophiobolos is said 

 to destroy the leaf and is perhaps the most dangerous of them. 



On sick and rotten trees of various species of Hevea, Allescheriella 

 uredinoides was found. 



In Java, Zimmermann in the Bull. Inst., Buitenzorg, has recorded 

 several fungi on Para rubber. Phyllosticta Hevese, Zimm., is a 

 fungus causing brown spots especially at the tips of the leaves ; Gloe- 

 osporium elasticae, Cooke and Mass., is another leaf fungus which 

 produces light greenish spots and masses of reddish spores 



Leaf Diseases. 



There are already several insects and fungi which live on the 

 leaves of the Para rubber trees, but none of them are very harmful. 

 To a very limited extent the annual fall of leaf that takes place on all 

 Para rubber trees after they have passed their second or third year is 

 an advantage when dealing with leaf pests, as the foliage can be easily 

 and regularly collected and burnt. Again, the leaves may happen 

 to fall prior to the formation of the spore-producing bodies, and in 

 this way assist, to some extent, in checking the spread of disease. 

 But it should be remembered that the Para rubber trees are in pos- 



* Nbtizblatt des Konigl. Botanische Gartens und Museums zu Berlin 

 (Vol. 4, No. 34, p. 133). 



