414 



THE AGRICULTURAL NEWS. 



December 27. 19 IS. 



PLANT DISEASES. 



THE CACAO CANKER FUNGUS AS A 



CAUSE OF COCO NUT BUD ROT. 



The following summary of the re.sults of a recent 

 research on coco-nut bud rot in the Philippines, by Otto A. 

 Keinking, is reproduced from the Pkilippim Journal of 

 Science^ Vol. XIV, No. 1, dated January, 1919 :— 



' Enormous losses, amounting tc^ thousands of pesos each 

 year, are produced by coco nut bud rot. As shown by the 

 Bureau of Agriculture reports, the disease is most prevalent 

 in Laguna, Tayabas, Pangasinan, and Zamboanga Provinces. 

 It is most abundant in very humid sections and in thickly 

 planted groves, both of which conditions are found on the 

 slopes of Mount Banahao. Field studies show that the spread 

 may be extremely rapid during favourable weather. 



' Ad organism similar to Bacillui col:, (Escherich) Mig., 

 and other saprophytic bacteria are associated with the disease. 

 Under certain conditions, such as a hoa't weakened by severe 

 injury, the former organism and Bacillus coli, (Escherich) 

 Mig , isolated from man or horse, may in inoculation experi- 

 ments produce disease. 



• A smmmary of the entire bacteriuiogical work done by 

 the present writer, including approximately 300 inoculations, 

 his indicated that, while the bacteria are always present and 

 are a factor in destroying the weakened tissues, they oannot 

 srcounl for the initiation of the disease or its prevalence and 

 rapid spread. 



'■PhytophOwru faberi, Maubl., isolated from cacao pro- 

 duces a typical bud lot of coconut .seedlings and of mature 

 C'jco-nut trees. 



' A fungus isolated from a typical field case of coco-nut 

 bud rot was found to be identical with Phytophthora faberi, 

 Maubl , is'lated from cacao. 



'■Phytophthora faberi, Maubl., isolated frrm the field case 

 of coco-nut bud rot produced in all inoculated seedlings a 

 . topical infection. 



^Phytophthora labeti, Maubl., isolated from the field case 

 of coco-nut bud rot, produced disea.><e in coco nut aeedlings, 

 cacao fruit, Hevea rubber .seedlings, and papaya fruit. The 

 .same species of fungus isolated from cacao fruit produced 

 disease in coco-nut seedling.s and mature trees, cacao fruit 

 and stem, Hevea rubber seedlings and mature trees, and 

 papaya fruit. 



'A morphologic and taxonomie study of the organism 

 isolated from coco-nut has proved that it is Phytophthora 

 mheri, Maubl., as described by Kosenbaum. 



'From these researches it can be stated that with certainty 

 that Phytophthora faberi, Maubl, causes coconut bud rot ; 

 bacteria are apparently, in the majority of cases, always 

 vecondary, but are concerned with destroying the weakened 

 tissues.' 



'By proving that the fungus causing coco-nut bud rot 

 i.s identical with the organism which produces blAck rot of cacao 

 pods, canker of cacao, fruit rot and canker of Hevea rubber, 

 and rot of papaya fruit, it becomes evident an entirely new 

 .•isries of controls will have to be devised, l hytopht ho ra faberi, 

 M»ubl , may grow readily, under favourable conditions as a 

 saprophyte also, on dead portions of cacao, cocri-nut and pa[)aya. 



UI'.COMMENDATION.i. 



'Trees when once severt-ly infected never rtcovtr. The 

 mode of growth of the palms and the nature of the disease 

 in»ke it imposeible to cure trees already badly affected. 



'Systematic inspection, condemning and burning of all^ 

 diseased coconut trees, as carried on by the Bureau of Agri- 

 culture should be cont inued. 



'All parts of diseased trees must be burned: otherwise the 

 organism will live as a saprophyte on dead matter, and thea 

 .spread to healthy trees. 



'Clean cultivation ought to be practised in all groves. 

 'Under no circumstances should coco-auts be interplanted 

 with cacao or papayas. 



'If coco-nuts are planted near diseased Hevea rubber, pre- 

 cautions should be taken to avoid the spread of the disease. 

 'Trees in new groves must be planted 10 metres apart 

 each way. This spacing is one of the most satisfactory means 

 of control against bud rot, and at the same time tends to give 

 the highest production of nuts.' 



The type of bud-rot to which the above summary refers 

 is one which affects the central leaves and causes rotting of 

 the heart, the older leaves remaining in a perfectly healthy 

 condition for some months later. It is highly infectious, 

 and most commonly attacks trees that have just come into 

 bearing. The trunk is not affected for more than some fc 

 inches at the top 



Notices of Mr. Keinking's paper have already appeared 

 in the Journals of the Agricultural Society of Trinidad and 

 of the Board of Agriculture in British Guiana, and the 

 announcement has naturally aroused great interest, from its 

 possible bearing on the bud-rot problem in the West Indies. 

 The present reviewer when recently in Trinidad, found 

 a tendency on the part of coconut planters to assume that 

 the results obtained in the Philippine.^ were immediately 

 applicable to the local afifection, while the British Guiana 

 Journal in an editorial comment states ; 'There is little doubt 

 chat a careful scientific investigation here will prove a similar 

 relationship ' between Pliytophtliora faberi and bud rot. 



Assumptions of ths kind are to be ilepieeated, and 

 there are special reasons for caution in the case of bud rot. 

 The writer has insisted from time to time on recognition 

 of the fact that the existence of bud rot in coco-nut palms is 

 not of itself evidence of the presence of a specific disease, or 

 of disease at all in the ordinary sense of the word. Bud rot 

 is a condition which may be induce) by mechanical, chemical, 

 or parasitic interference with the life processes of the palm. 

 The material of the ' heart ' is extremely tender, and when 

 the natural resistence of the living tissue is reduced, it affords 

 a highly nutritive medium suitable for the rapid development 

 of any of a large variety of possible invading organisms. In 

 the case of epidemic or infectious bud rot, the issue i.s narrow- 

 ed down to the respou' ibility of a transferable parasite but 

 there is no ground for assuming that the parasite coneerned 

 in producing a condition of .such a general nature if necess- 

 arily or even probably the same in different situations, 

 J. K Johnston, now confirmed to some extent by Keinking, 

 has put forward evideace to show that Bacillus coli may be 

 effective in setting up coco-nut bud rot. The widely prevalent 

 and destructive bud rot of palms in Southern India has been 

 long known to be due to Phytophthora pahnivora (Pythium 

 palmivorum), and the same fungus has recently been found 

 by S. F. Ashby in connexion with coconut budrot in 

 Jamaica. 



The need for caution emphasized above is at the same time 

 an indication of the need for furihtr examination of bud rot in 

 different parts of the West Indies, in the light of the Philippine 

 discovery. Ileinkinn'u piper affords valuable evidence of 

 the manner in which a fungus parasite may be masked by 

 early bacterial infestation, and provides an interesting parallel 

 with the history of the investigation of the same fungus in. 

 connexion with cacao pod rot. 



