254 



THE AGRICULTURAL NEWS. 



August 6, 1910. 



FUNGUS NOTES. 



RECENT WORK ON DISEASES OF 



COCOA-NUT PALMS 



The information contained in the following article is 

 taken from Cirruhnit n-ntl A<jricHlturaI Journal of the Roi/al 

 JJotanic Gardens, Cei/lnv, Vol. IV, Nos. 22 and 24, on ' The 

 Stem Bleeding Disease of the Cocoa-nut ' and ' The Root 

 Disease of the Cocoa-nut Palm', by Fetch, and from two 

 articles in the Bulletin of the department of A;iriciilture, 

 Trinidad, Vol. IX, No. 64, the first entitled ' The Bud Rot of 

 the Cocoa-nut Palm', by Rorer, the second ' Cocoa-nut Palm 

 Diseases', by Mr J. B. Johnson, Assistant Pathologist to the 

 United States Department of Agriculture. The diseases 

 described in these pipers are three in number, namely, the bud 

 rot disea.se, the root disease, and the stem bleeding disease. 

 BUD EOT Di.sEASE. According to Rorer and Johnson 

 it is now almost certain that this well-known disease of 

 cocoa-nut palms is due to the action of bacteria. The causa- 

 tive organism has not yet been definitely separated, but evid- 

 ence accumulated from various parts of the world leaves very 

 little doubt as to its nature. The disease, as is well known, 

 occurs in .several islands of the West Indies, and one with 

 very similar characters has been found in various parts of the 

 East, particularly in India, Ceylon and the Philippines. 



In Trinidad bud rot is usually distinguished ' by the 

 yellowing and drooping of the leaves, the falling of the imma- 

 ture nuts, the wilting and breaking over and browning of the 

 terminal leaf and the putrid condition of the whole of the 

 region of the cabbage'. Apparently the disease may com- 

 mence either in the young central tissues or at the base of the 

 outer leaves. In the latter case its action is not so rapid as it 

 is in the former. In Ceylon it would seem that the disease 

 always commences in the cabbage, and the young erect leaves 

 become brown and dead, while the outer whorl of leaves is 

 still apparently healthy. The fact that the disease commences 

 at the centre and not at the outside is one of the characters 

 by which it can be separated from the root disease as found 

 in the latter island. ;-! 



Various methods of dealing with this disease have been 

 suggested, and it is possible that in very early stages flaming or, 

 in the case of young plants, the use of Bordeaux mixture may 

 be found effective in checking it, but in advanced cases 

 little can be done in the way of remedial measures, and the 

 safest course to pursue is to promptly and thoroughly destroy 

 all trees showing advanced symptoms of the disease. In 

 Trinidad, the Board of Agriculture voted the sum of §500 for 

 the purpose of destroying diseased trees, and the work was 

 started on November 30, 1-909, under the direct supervision 

 of an agricultural inspector. 



ROOT DisE.vsE. A root di.seasB of cocoa-nut palms is 

 reported from both Trinidad and Ceylon, but the accounts 

 given from the two islands would appear to indicate that 

 they are not due to the .same organism. The Trinidad disease 

 was described by Stockdale in 1906, and attributed to 

 a species of Botryodiplodia. A similar disease of cocoa-nut 

 palms at Travancore in India is described by Dr. E. J. Butler 

 and also attributed by him to a species of Botryodiplodia. 

 The symptoms of root disease in Trinidad, as described by 

 Stockdale, are somewhat similar to that of the bud rot. It 

 may be recognized by a yellowing and hanging down of the 

 leaves, by the disorganized condition of the cortex of the 

 roots, by the formation of a red ring of discolouration in the 

 stem, and by the eventual' death and rotting of the cabbage. 

 The diseased roots generally contain the mycelium of the 



fungus called Botryodiidodia sp. As a result of a critical 



examination of the literature, Johnson is of the opinion 



that Stockdale's conclusions were not warranted, and 



states that, according to his own observations, the disease 



of the roots is of bacterial origin and in all probability due to 



the same organisift as that causing the bud rot disease, so 



that in reality the bud rot and the root diseases of cocoa-nut 



palms in Trinidad are identical in origin. Johnson appears 



also to be of the opinion that the various forms of bud rot 



met with in ditferent parts of the world are identical, and due 



to the same organism as is found in Trinidad. Since this 



is the case, it is evident that the root disease found in Ceylon 



cannot be considered as identical with that in Trinidad, for 



Petch proves almost conclusively that the disease is due to 



a fungus. Fames : lucidus, which belongs to the family of 



bracket fungi. The symptoms characterizing the disease in 



Ceylon are as follo»'s : '(1) The outer leaves wither and droop, 



usually remaining for a long time suspended vertically 



around the stem; (2) the tree becomes barren owing to the 



suppression of the flowering branches; (3) new leaves are 



successively smaller, so that the crown becomes a handful of 



dark yellowish leaves; (4) finally these small leaves wither 



and the bud decays.' Instances were noted in which the 



tree was killed so rapidly that the leaves and terminal bud 



dried up before the decaying of the latter had time to 



commence. The fungus causing the disease develops in the 



outer ring of vascular bundles in the butt of the tree, that 



is from the ground level to a distance of about 3 feet 



above the ground. The water-conducting cells become 



filled with hyphae, and in this way the food supply from 



the roots is cut off. The mycelium of the fungus is, in 



general, white but the older hyphae are often brownish in 



colour. Another fungus, Lasiodijdodia theobromae, which is 



better known in connexion with the di^ea.ses of cacao, was 



frequently found to occur in the dead roots of cocoa-nut palms, 



but careful investigation showed that it was almost certainly 



saprophytic in this case. It may be stated here that the fungus 



referred to by Stockdale as Botri/odiplodia .sp., and found on 



dead roots of cocoa-nut palms in Trinidad, is now known to 



have been also, in all probability, Lasiodiplodia theohromae. 



In addition to attacking cocoa-nut palms, Fomes lucidus can 



affect bamboos, mango and flamboyant (Poinciana regia). As 



noted above. Fetch calls attention to the difference between 



the symptoms typical of the root disease as found in Ceylon, 



and those characteristic of bud rot disease. It may also 



be noted that the root disease in Ceylon differs from that 



in Trinidad in the absence of the red discolouration of the 



stem, and in the fact that the terminal bud is frequently 



quite healthy. 



In the case of monocotyledonous plants such as the cocoa- 

 nut palm, there is not much possibility of treating root diseases, 

 but the following preventive measures are recommended: all 

 diseased trees should be felled, and the butt, wdth the last 2 or 3 

 feet of the stem, burnt. It is not necessary to burn the upper 

 portions of the tree as these are not infected by the fungus. 

 When the tree has been felled, a trench at least 2 feet deep 

 should be dug around the roots, which may then be left in 

 the soil to decay. There is very little likelihood that these 

 roots will serve as a source of infection, since the food supply 

 which they contain is rapidly consumed both by the fungus 

 cau.sing the disease, and by numerous other saprophytic fungi, 

 .such as Lasiodiplodia theobromae, which has already been 

 alluded to ; when the food supply is exhausted these fungi 

 will neces.sarily die of starvation. Lastly, it is advised that 

 the hole from which the tree has been removed be left open 

 for at least one year. 



STEM BLEEDING DisE.\isE. The 'symptoms of this disease 



