94 



THE AGRICULTURAL NEWS. 



March 16, 1912. 



FUNGUS NOTES. 



BUD ROT OF THE COCOA-NUT PALM. 

 Part I. 



The bud rot disease of cocoa-nut palms has been known 

 in the West Indies for many years, and has caused serious 

 losses in some cases, particularly in Cul>a: but although this 

 is so, and though many workers have devoted time and 

 attention to its investigation, its true cause has only very 

 recently been determined, and there are still many miscon- 

 ceptions of its origin, and of the efficacy of the different 

 methods of treatment that have been suggested. The account 

 of an extensive and careful investigation, which has led to 

 a clear understanding of the symptoms and causes of the 

 disease, has recently lieen publi.'^hed as Bulletin No. 228 of 

 the Bureau of Plant Industry of the United States Depart- 

 ment of Agriculture. The work has been carried out by 

 J. E. Johnston, late Assistant Pathologist in the Laboratory 

 of Plant Pathology, now Pathologist to the Estacion Experi- 

 mental de la Associacion de Productores de Azucar de Puerto 

 Rico, who investigated the disease in Cuba, and also visited 

 Jamaica, Trinidad and British Guiana, for the purpose of 

 comparing the forms of disease reported from those localities 

 with that found in Cuba. The results of this work are given 

 below. 



SYMPTOMS OF THi-; DisEA.-iE. The accouut of these, in 

 Mr. Johnston's own words, is as follows: ' The common name 

 of the disease, bud-rot, well describes its nature, for in its 

 acute or advanced stages the bud of the tree, i.e., the growing 

 point in the centre of the crown, is affected by a vile-smelling 

 soft rot which destroys all the younger tissues. At this stage 

 most of the nuts have fallen, the lower leaves are turning 

 yellow, and the middle folded and undeveloped leaves are 

 dead and hang down between the still green surrounding 

 leaves. Signs of the disease in its incipiency are (1) the 

 falling of immature nuts; (2) a staining of the open flower 

 spikes, partly or wholly, to a rich chocolate brown; and (3) the 

 dying and bending over of the middle undeveloped leaves. 

 When the nuts are being shed, investigation reveals at the 

 base of the affected spikes a dark-coloured wet rot which 

 spreads around the leaf sheaths, or strainers, as they are 

 locally known. This rot appears as water-soaked areas which 

 may reach a length of 15 or 20 cm. on both the upper and 

 lower surfaces of the bases of the leaves. This condition often 

 penetrates the leaf bases to a depth of 2 cm. or more, and the 

 tissues involved in it swarm with bacteria. As the white 

 tissues at the base of the leaf become old and green the 

 water-soaked spots harden, and they may often be found in 

 this condition on otherwise perfectly healthy trees. 



' The rot gradually spreads from the base of one spike 

 to another through the wet strainer. It is probable that 

 insects carry the disease from one part to another, since there 

 may lie one or more points of infection. Gradually all the 

 spikes become affected and shed their nuts, and the leaf stalks 

 become so rotted at their bases that they are not able to 

 maintain their natural position, but are pendent, often for 

 a long time, or else fall off. 



' If the infection starts in the central leaves the disease 

 is apt to progress rapidl}- downward into the younger tissues, 

 which it is very active in disintegrating, the vascular bundles 

 being so soft as to allow the tissues to go entirely to pieces. 

 In the centre it may progress into the trunk for a short dis- 

 tance and rot out the fundamental tissue, leaving only the 

 fibres which are too hard to be disintegrated. This rot has 

 been found, exceptionally, as far as TS metres under the 



heart of the bud, a hard outer shell lieing left around the 

 central rotted portion. U.sually the decay extends in the 

 trunk under the bud for a distance of only 02 to 0'5 metre 

 and never throughout its length. 



' Spots which are merely fungus infections often occur 

 on the middle leaves. These spots spread and coalesce, leav- 

 ing blackened, wet, and later, dry and dead tissues. Insects 

 and small animals are often found in the decaying tissues, 

 but the advancing margin of the soft rot appears to be occu- 

 pied exclusively by bacteria.' 



DISTRIBUTION. Johustou's principal investigations were 

 conducted in Cuba, but he also found a bud rot with exactly 

 similar symptoms in Jamaica, Trinidad and British Guiana. 

 Its spread and general effect are most serious in Cuba; in 

 Jamaica where it used to be prevalent, the destruction of 

 diseased trees, and general sanitary measures, have reduced it 

 very greatly, so that Johnston estimates that probably only 

 about fifty cases existed there at the time of his visit ; while 

 in Trinidad he found it to be fairly prevalent and responsible 

 for consideraljle damage. Since then, however, an active 

 campaign for the destruction of diseased trees has been insti- 

 tuted by the Board of Agriculture, in the latter island, and 

 the majority of them have been destroyed, so that only a few 

 cases can now be found. In British Guiana the disease 

 is present though not very virulent in form. 



l)iseases with very similar symptoms have been reported 

 by other observers from the Cayman Islands and from British 

 Honduras. Although full accounts of these are not available 

 in all cases, and though careful comparative investigations 

 have not been made, there is not much doubt that these 

 diseases are the same as bud rot It may here be noted that 

 one or two instances of a disease strongly suspected of being 

 the same as that under consideration have been reported from 

 certain of the smaller islands of the Lesser Antilles. Old 

 traditions of the wholesale destruction of cocoa nut planta- 

 tions still linger in some of them, and lead to the surmise 

 that possibly at one time or another bud rot has been present 

 in the majority. 



It is interesting to note that, although there have been 

 reports of the existence of bud rot in Porto Pico, Johnston did 

 not find it there; neither did he observe it in New Providence 

 Island, in the Bahamas, nor ia certain small groves along 

 the Coast of Colombia and Venezuela; while according to 

 Professor Rolfs and Dr. Bessey, it is also absent from 

 Southern Florida. 



Diseases witlT similar symptoms, also attributed to bac- 

 teria, have been reported from the Philippines and Ceylon, 

 and these are very probably the same as the West Indian 

 disease. From German East Africa, Portuguese East Africa 

 and Tahiti, there are reports of a similar disease which cause 

 it to be very desirable that comparisons should be made with 

 the local disorder. In India, a similar disease of certain palms 

 in Travancore has been attributed by Butler to a fungus, 

 Pythium jialmivorum, while Coleman has found another 

 fungus, Phytophthora omnipora, var. Arecae on the Areca 

 palm in Mysore. (See Agricultural Jfews, Vol. IX, p. 254 

 and Vol. X, pp. 14, 30 and 206.) 



CAUSE. The disease has been attributed to very many 

 different causes by various observers, and its infectiousness 

 has been doubted or ignored by some. In connexion with 

 the agents to which the disease has been ascribed, Johnston 

 writes as follows: 'By many it has been thought due to some- 

 thing in the soil or to the climatic conditions, and various 

 applications have been made to the Ijase of the tree in the 

 hoi* of curing it. Insect.s eating the roots and working in 

 the trunk or in- the crown have also been con.sidered as 

 causes. It has likewise been claimed that a mechanical 



