318 



THE AGRICULTURAL NEWS. 



October 1, 1910. 



FUNGUS NOTES. 



SOME DISEASES OF RUBBER TREES. 

 PART II. 



.STEM DisEASE.s. Tlie.se, though nuiuerou.s, are mainlj" 

 confined lo Hevea, with the exception of that caused by 

 Corticium javanicuin, Zimm., which also occur.5 on Castilloa 

 in Java. The principal ones are as follows: — 



Ceylon canker, attributed to Nectria diversisjjora, Fetch; 

 Ceylon bark disease, due to Corticium Javanici/m, Zimm.; 

 Malay bark disease, due to Corticium ccdceum, Fr.; die back, 

 due to Gloeosporium alboruhnim, Fetch, frequent!}" followed 

 by Botryodiplodia elasticae, Fetch, black canker, in the 

 Dutch East Indies, due to Fusir/adiuiii sp.; new bark disease, 

 in the Malay States, due to Diplodia rapax, Massee; new 

 stem disease, in the Malay State.s, due to Euti/pa caulixora, 

 Massee; a branch and stem disease, in the Malay States, 

 not yet completely worked out, possibly due to Corticium 

 javanicum; horse-hair blight. 



All of these occur on Hevea. In addition, a disease of 

 Funtumia similar to the canker of cacao in Ceylon, has 

 been reported from Uganda; it is attributed to Nectria 

 funtumiae, Massee. Corticium javanicum attacks Castilloa 

 in Java, and Botryodiplodia elasticae has been found on 

 certain specimens of the same plant which had previously 

 been damaged by fire in Ceylon. 



Ceylon canker on Hevea was described by Carruthers in 

 .the Circidars and Af/riniltiiral Journal of t/iK Royal Botanic 

 Gardens, Ceylon, Vol. II, p. 4-1:6. The disease was discovered 

 in November 1903, but was not of very wide distribution, .so 

 that the usual remedial measures for canker which were 

 employed to control it were successful in almost eliminating 

 it from the island. Though the term canker has been em- 

 ployed to describe it, no typical open wound is formed. There 

 are no very definite external characteristics, except that the 

 bark over the aflected .spot appears different from that over 

 healthy tis.sue. It may be darker in colour, or split in a differ- 

 ent manner. The diseased tissue below this bark is of a dirty 

 yellow, or neutral tint, deepening, as the attack proceeds, to 

 claret colour. Xo latex will flow from such parts. The causat- 

 ive fungus usually attacks the lower portions of the stem 

 and the lower branches, but never occurs on the roots. The 

 remedial measures consist, as usual, in excising the affected 

 areas, and tarring the resultant wounds. The disease has 

 been attributed to a species of Nectria, found on infected bark 

 by Carruthers, This was also found on dead branches of tea, 

 and on Hevea fruits by Fetch, and named Nectria diversispora, 

 Fetch. The parasitism of the species does not appear to have 

 been satisfactorily established. (Fetch, Annual Report of the 

 Mycologist, 1905, Circulars and Aijriculturcd Journal of the 

 Royal Botanic Gardens, Ceylon, Vol. Ill, p. 281, etc.) 



The bark disease due to Corticium javanicum was 

 described in the A(jricnltnral News, Vol. IX, p. 286, and 

 need not be further dealt with here, except to add that, in 

 some instances where the development of the fungus is check- 

 ed, the wound often becomes surrounded by callus, and in this 

 way an appearance is caused which is very similar to that of 

 canker. It is interesting to note that some authorities con- 

 sider Corticium lilacino-tuscum, B. and C, as identical with 

 Corticium jivanicum, in which case care should be taken in 

 these islands to keep pink disease of cacao well in check, for 

 fear the causative fungus may spread to Hevea, on which 

 host it seems to be capable of causing considerably more 

 serious damage than on cacao. References to this disease 

 may be found in the Agricultural News, loc. cit.; also, Bernard, 



Bulletin XII, p. 21, du Departement de I'Agriculture aux 

 Indes Neerlandaises; Zimmermann, Alededeelingen uits Lands- 

 plantentuin, LXVII, p. .t1; and Bulletin de I'lnstitut 

 Botanique de Buitenxorg, X, 1901. 



The Malay bark fungus, Corticium calceum, Fr., is known 

 as the writing fungus, because the patch formed by it often 

 splits up in a manner suggestive of hieroglyphics; its general 

 effect is very similar to that oi C. javanicum, as has been 

 pointed out heiore {Agricultural News, Vol. IX, p, 286, where 

 further references are given). 



Die-back disease, which occurs in Ceylon, has already 

 been described in the Agricultural Neivs, Vol. IX, p. 270, 

 and, as it was considered at .some length, it need not be further 

 mentioned here. 



The black canker disease in the Dutch East Indies appears 

 on the branches of trees that have been pruned, and on the 

 tops of pollarded trunks. It is not of very wide distribution, 

 and should yield readily to treatment. The progre.ss of the 

 disease is as follows: the leaves wilt, turn yellow, dry up 

 and fall: the flow of latex rapidly diminishes, and very 

 soon ceases altogether. A few days later, the tree is dead. 

 In some cases, however, only the upper parts die, and the 

 tree puts out branches from below the diseased area. The 

 bark of the parts attacked splits, and scales ofl", and between 

 it and the wood the mycelium of the causative fungus 

 appears as a l>lackish down. Among the hyphae of this 

 mycelium, the brown bicellular conidia of a species of Fusi- 

 cladium may be found. The hyphae themselves are brown, 

 septate and branched; after destroying the bark, they 

 penetrate the young wood ami give it a dark colour. As 

 preventive measures, Dr. Bernard, by whom the disease was 

 first described, recommends careful tarring of wounds made 

 in pruning, and filling of the central hollows in the trunks 

 after pollarding. When the trees are not dead,, the whole of 

 the diseased portion, as indicated by the colour of the wood, 

 .should be removed and burned, and the wounds so made 

 tarred. (Bernard, Bulletin XII du Departement de I'Agri- 

 culture aux Indes Neerlandaises.) 



In the Agricultural Bulletin of the Straits and Federated 

 Malay States, Vol. VIII, p. 310, an account is given by the 

 editor, Mr. H. N. Ridley, M.A., of a black fungus occurring 

 on Hevea in Perak; the disease was also reported a little later 

 from Selangor (loc. cit., p. 521). The attack commences on 

 the shoots, which turn black and die, and eventually the 

 disease spreads to the trunk, and kills the tree. The bark of 

 the branches aflected shows numerous raised spots, which 

 eventually .split, and reveal the black fructifications of 

 a fungus. Older branches show large elevated patches, of 

 a black colour, looking as if soot had been thrown on the 

 tree. The fungus kills the cambium and turns it black, and 

 the wood soon dies; it is active during the wet season, but 

 becomes stationary in dry weather. Diseased parts should 

 be cut back to a point where latex flows healthily, infected 

 material [nomptly burned, and the bark below the attacked 

 areas treated with Bordeaux mixture. It is also suggested 

 that spraying all trees in an affected district might prove 

 useful. The fungus was first thought by Ridley to be 

 a species of Cucurbitaria, but specimens sent to Kew were 

 identified by Massee as a new species of Diplodia, and 

 named Diplodia rapax. In making this identification, 

 !Massee remarks that the appearance of the fungus suggests 

 that it is a stage in the life-history of a Rosellinia. This is 

 interesting, as a species of Rosellinia has recently been found 

 on Castilloa stems in Grenada. Dipdodia rapax also occurs 

 on Hevea in West Africa. (Agricultural Bulletin of the 

 Straits and Federated Malay States, Vol. VIII, p. 570; 

 Few Bulletin, 1910, No. 1, p. 3.) 



