Vol. VII. No. 163. 



THE AGRICULTURAL NEWS. 



219 



DISEASES OF COCOA-NUTS IN TRAVANCORE. 



Considerable interest, has, of late, been taken in 

 the diseases of cocoa-nut palms. The Mycologist' 

 (Mr. F. A. Stociidale B.A., F.L.S) on the statt' oC this 

 Department has carefully studied the fungus diseases 

 prevalent in Trinidad and British Guiana. 



His report on a visit to Trinidad was given in 

 abstract in the A(/ri,i-iiltuml A^eiv.t, Vol. VI, p. 75, 

 and attention w.as called to (1) root disease, (2) leaf 

 disease, and (3) bud rot. The root disease was found 

 to be the most serious and was causing considerable 

 loss in some districts. 



The ibllowing extracts taken from a report by 

 Dr. E. J. Butler, Imperial Mycologist for the Govern- 

 ment of India, in which he describes a root disease of 

 cocoa-nut palms in Travancore caused by afungus similar 

 to that founil by Mr. Stockdale to be as.sociated with 

 the root disease in Trinidad, are full of interest: — 



As a general rule the lirst indiL-atioii tliat a cocoa-nut 

 palm is attacked is the (jjjening out of the outer leaves from 

 the head. The leaf stalk becomes slightly flaccid and the 

 weight of the leaf causes the whole to droop. Then the ends 

 of the pinnae or leaflets at the extremity of the leaf become 

 flaccid and hang down almost vertically. This is accompanied 

 by a loss of colour; the drooping and discoloration of the 

 leaflets then e.xtend gradually backwards to the whole leaf. 

 Later on, the tijjs of the leaflets turn yellow and dry up, 

 followed gradually by the entire leaf, which eventually hangs 

 down withered from the crown. One after another, or many 

 together, all the leaves are sinularly affected. Intermediate 

 conditions are common ; young trees often have a large 

 proportion of leaves healthy witli only a few yellowed, others 

 have all the leaves equally discoloured and drooping at the 

 tips of the leaflets, before any dry up. 



After the leaves, the most extensive alterations are 

 found in the roots of diseased palms. 



Each main root of a palm gives off nundjers of wlnte 

 lateral roots, which again give ott' others. Except in advanced 

 •cases of disease, the main roots of a diseased tree will be 

 found for the most part unaltered. A large proportion of 

 the lateial roots are however njtted, and, in some cases, this 

 rot extends back into the main roots and even into the base 

 of the stem. 



Lateral roots affected l>y the rot mentionetl above are 

 invaded by a parasitic fungus, which enters from the soil and 

 develops the miiuite threads of wliich its body is composed in 

 and between the cells of the cortex. When a root becomes 

 invaded by this parasite the cortical cells are killed as soon as 

 the thread of the fungus reaches them. They quickly turn 

 brown and collapse. Tins is especially marked in the large 

 thin-walled cells of the inner layers. At a later stage the 

 •whole root appears l:(lackene<i and shrunken as a result of the 

 death of a large lunnber of its cells; it can evidently no 

 longer perform its work of taking in food, and decomposition 

 rapidly sets in. The threads of the parasite are of twr) kinds 

 The older ones are deep brown and comjiaiatively large. 

 From them arise finer colourless branches. All are divided 

 into segments by transverse walls. In older stages masses 

 of these brown threads become crowded together and divide 

 freciuently, so that a brown patch of fungus tissue is formed. 

 In this at a still later stage, spore capsules are developed 



under the rind and these burst out to open on the surface of 

 the root and discharge spores. 



The spores are I'ather large, egg-shaped bodies, colour- 

 less and single when young, but divided into two cells and 

 deep brown when older. It is a species of the genus 

 lldtri/odiploiliii, of which several parasitic members are known. 



Quite recently ^Mr. V. A. Stockdale, .^^ycologist to the 

 Imperial Department of Agriculture, West Indies, has 

 described a similar and perhaps identical species as the cause 

 of a cocoa-nut disease in Trinidad. The symptoms of 

 this disease are on the whole sinular to those desci-ibed above, 

 and it appears to be possible that both are really the same. 

 There is no absolute ex])erimental proof that the Botfi/Mli- 

 jilodl'i is the cause of the disease either in Travancore or in 

 Triindad. It is not even certain that the two are identical, 

 as the scientific description of the latter has not yet been 

 l)ublished. So far as can be gathered from Mr. Stockdale's 

 report, the spores of his fungus were not found actually on the 

 cocoa-nut roots, but only on the leaf petioles, though he 

 attributes the death of the roots to a fungus found in them 

 and appaiently agieeing with that on the petioles. In 

 Travancore, the Botri/odljilodld was only found on roots and 

 was obtained from diseased roots of areca as well as cocoa-nut 

 palms. Spores were not found on roots actually in the soil 

 but developed on diseased roots after these had been dug up 

 and kept for some time. Only the early stages of formation 

 of the .spore capsules were found in freshly dug roots. The 

 brown threads within the roots were found in these cases to 

 comnuuucate with the spore capsules, both immature and 

 ripe, and there is no doubt that the threads in diseased roots 

 belong to the Bofri/odiplodia. Scientific proof that this 

 fungus is the cause of the disease can only be obtained by 

 inoculating the roots of healthy palms with a culture of the 

 fungus and thereby producing disease. 



The intensity fif the disease differs greatly in ilifl'erent 

 localities. It spreads most rapidly and is most severe in the 

 low-lying, badly drained lands. The spread has probably occur- 

 ed from one or a few centres, which were early attacked, 

 and every evidence tends to prove that the disease is infec- 

 tious. The spread of the fungus takes jilace in the soil. 

 Cultivation hinders it, owing to the disturbance and conse- 

 quent aeration of the upper layers of soil, and improved 

 drainage is to be recommended. 



The remedial measures suggested consist of : (1) the 

 destroying of all diseased material and so preventing 

 infection of healthy palms, (2) the experimental trial of 

 ordinary manures, supplemented by ammonium suljihate, lime, 

 sulphur, and sulphate of iron, (3) improving the general 

 health and vigour of the trees by high cultivatifin, (4) search 

 for disea.se-resistant varieties, and (5) the prohibition of living 

 plants and of roots (said to be used for fuel by metal 

 woi-kers and also as medicine) from disease infected areas. 



Preliminary inoculation e.xperiments conducted 

 by Mr. Stockdale in the laboratories of the Imperial 

 Department with the species oi Boiryodiplod ui, found at 

 Trinidad, and subsequently also received from British 

 Guiana, would indicate that this fungus is parasitic in 

 habit, and may infect healtiiy roots of cocoa-nut palms. 

 It is hoped, at a hiter date, to duplicate these experi- 

 ments and then to issue a brief report on the results 

 obtained. 



