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The special part, in which the pests of Hevea braziliensis (Para), 

 Ficus elastica (Eambong), Castilloa elastica, Kickxia elastica, and 

 Mamhot Glaziovii (Ceara) are detailed one by one is preceded by an 

 interesting introduction in which the author advances some general 

 considerations on plant disease, and complains incidentally of the bad 

 condition in which material sent in for identification is received. He 

 says that during the past two years planters have frequently sent 

 to the Department of Agriculture at Buitenzorg specimens of rubber 

 plants attacked by diseases more or less serious. Unhappily the 

 material, being for the most part badly packed and having been for a 

 greater or less time in over-heated waggons or in store-rooms, arrived 

 in such a bad state that it was impossible to make a serious examina- 

 tion of it or to give the real cause of the injury done ; the humid warm 

 atmosphere which surrounded the plants favoured the devolopment of 

 a crowd of organisms among which it was impossible to distinguish 

 the originator of the disease. 



" It is necessary in the first place to give a few recommendations 

 which may appear common-place, or at least elementary, but on 

 which it is nevertheless good to insist and which are important to keep 

 before one's mind when occupied with plant disease- 

 It is not necessary, I think, to delay long on questions pertaining 

 to soil, drainage or manure. I have occasionally seen a soil, excellent 

 in outward appearances, which at a depth of a foot or so changed its 

 constitution and became for example clayey and damp. This miy be 

 serious in the case of plants with a tap root such as Hevea ; when the 

 root reaches the wet layer of soil, it will be in a condition to rot and 

 to become a source of disease. Enough account is not always taken of 

 the richness of the soil in nutritive substances. I have been able to 

 demonstrate several instances of plants becoming the prey of various 

 parasites, because the soil having been previously exhausted by long 

 cultivation the plants were debilitated and had not the force to resist 

 their enemies. 



I wish to insist on a knowledge of the importance of proper 

 surveillance and of the immediate notification to competent persons of 

 the least appearance of unhealthiness among the plants, whether it may 

 appear serious or mild. This recommendation is important for rubber 

 plants. Their cultivation is not yet very extensive in Java, or at least 

 has only developed within the last few years ; but as it has made 

 remarkable progress it is necessary to give it the greatest attention. It 

 is much easier to protect a cultivation in the way of formation against 

 its enemies, than to save old plants from parasites which have multi- 

 plied at their convenience on account of special circumstances. 



Diseases of Hevea braziliensis. 



(a). Corticiitm javanicum, Zimm. This appears to be the most im" 

 portant disease of Hevea. The parasite is well known from the havoc it 

 has caused among coffee, where it attacks the stems and fruits. 

 Zimmermann, who discovered it on Hevea, attached great importance 

 to it, and proved that it is a true parasite which kills the branches 

 which it attacks. During the past two years I have studied several 

 cases w 7 here the parasite brought about the death of the plant. 



