and Magazine of the Ceylon Agricultural Society. 



403 



gave, up to a year or two ago, an average of 

 twenty nuts per bunch : it is now diseased and 

 gave this year only three or four. The top of 

 the stem and the white internal part of the 

 crown (known as the "cabbage") are quite 

 normal, except in old cases, just before death, 

 when the latter rots. Even in severely affected 

 palms no trace of the disease or of any unhealthy 

 condition can be found in these parts. The 

 rest or the stem is equally healthy in appear- 

 ance ; I was told that wood from diseased trees 

 is weaker than from healthy and it is certainly 

 more spongy in texture. In some cases 

 cracking of the rind with exudation of 

 gum occurs in the early stages; it is not a 

 general sympton but only seen in a fow cases. 

 As in palms everywhere, discoloured patches on 

 the rind are frequent, but they are mostly super- 

 ficial and entirely unconnected with the disease. 

 A brown discolouration frequently appears after 

 cutting open the trunk. This is apparently 

 more marked in diseased than in healthy trees. 

 It is not visible when first cut, is quite uncon- 

 nected with any parasite and is probably due to 

 an oxidation process. 



The absence of any parasite in the stem is of 

 interest. A coconut disease similar in many 

 respects to the Travancore disease has recently 

 engaged attention in Ceylon. It has been at- 

 tributed by the Government Mycologist, Ceylon, 

 to a fungus known as Thielaviopsis ethaceticus, 

 well known as the cause of tho "pine-apple 

 disease : ' of sugarcane. A similar fungus oc- 

 curred with such regularity on the cut stems of 

 coconut palms wherever examined in Travan- 

 core that the likelihood of its being the cause 

 of the disease appeared considerable. Further 

 investigation showed that this is not the case. 

 Tho fungus though allied to the cause of "pine- 

 apple"disease,is a distinct species of Thielaviopsis 

 It occurs equally on healthy and diseased palms 

 aud on all or most of the Indian species, being 

 common on coconut, areca, palmyra and date. 

 It is found on cut surfaces of roots, stem and 

 crown and appears freely on split areca nuts 

 that are perfectly healthy. Hence its spores 

 must be very widely distributed on the sur- 

 faces of palms, and in the air in palm-growing 

 tracts. As it 



LENDS ITSELF EMINENTLY TO EAPID DISSEMINATION 



this fact alone would be enough 

 to put it out of court as a cause of the 

 disease, for the progress of the latter is 

 extremely slow. Even more definite 

 evidence is fortunately available. It occurs 

 equally freely on palmyra and date palms at 

 Pnsa where no serious palm disease is known. 

 It has also been encountered in Sylhet on areca 

 oalms, in the Godavari on palmyra and coconut, 

 and on date palms from Sind. In none of these 

 areas is there a similar disease to that in Travan- 

 core. Further slabs of the stem of diseased 

 coconut palms in Travoncore were cut out with 

 a red hot knife under asceptic precautions and 

 incubated. These did not give rise to any 

 fungus when kept from exposure to the air, 

 though whon uncovered they quickly showed a 

 characteristic growth of Thielaviopsis. Hence 

 whatever be the cause of the Ceylon disease, the 

 palm Thielaviopsis is a perfectly harmless fun- 

 gus in India, so far as is at present known, and 



certainly has nothing whatever to do with the 

 Travancore disease. After the leaves, tho most 

 extensive alterations are found in the roots of 

 diseased palms. As the roots themselves show 

 differences in the sandy soils of the littoral tract 

 and the heavy alluvium of the inland valleys, 

 they will be separately described. In the sandy 

 soils of the coast and the light silts of the back- 

 waters the main roots extend both downwards 

 and laterally for great distances. For most of 

 their course they are unbranched, finger-like 

 structures, covored with a reddish bark, usually 

 straight and gradually diminishing from three 

 quarters of an inch or more to half an inch or 

 less in diameter. From their structure they 

 must he considered to be primarily "fix- 

 ing" roots, whose chief function is to 

 fasten the tree into the soil. Water and 

 food-suphes taken in by the feeding roots must 

 pass to the stem through them, but it is impro- 

 bable that they themselves play any part in ob- 

 taing supplies. From these main roots the lateral 

 roots are given off at intervals, and from the 

 lateral roots finer rootlets arise. The roots of 

 the second and third order are snr>all, white, 

 softer and less brittle than the main roots and 

 appear to extend only a short way from the 

 parent root. 



FOOD AND WATER ARE TAKEN IN 



by the finer rootlets, which thus have functions 

 of the highest importance in the economy of the 

 tree. In the heavy alluvial soils of the sub- 

 montane area the roots do not run to anything 

 like the length of those in sandy soils. The main 

 roots are smaller, much curved and twisted and 

 frequently branched. The lateral feeding roots 

 are given off closer together and are better 

 developed than in the other case. 



In the sandy soils food-supplies are scanty. As 

 are suit an effort is made by the tree to tap an 

 large an area as possible. It can hardly be 

 doubted that this is the explanation of the long 

 exploring roots of palms in the littoral tract. 

 The valley soils of the interior are, on the con- 

 trary, rich in organic matter washed down from 

 the hills and food is present in sufficient quan- 

 tities near the base of the stem. Hence there is 

 no need for the penetration of a considerable 

 bulk of soil and the roots mass and ramify in a 

 comparatively small space. In consequence of 

 the larger expanse of roots an examination of 

 the entire root system of any but seedling palms 

 is practically impossible in the sandy area. The 

 following account is therefore based chiefly on 

 conditions observed at Pulliyanur in deep valley 

 soils ; such examination as was possible at 

 Alleppey on the coast was only sufficient to 

 show that the essential features are the same. 

 In seedling coconut palms the main root 

 arise densely crowded together from all parts 

 of the swollen base of the stem, and diverge 

 in every direction. Each main root gives oil' 

 numbers of white lateral roots, which again 

 give off others of the third order. 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 LATERAL ROOTS ARE HOWEVER ROTTED 



and, in some cases, this rot extends 

 back into the main roots and even to the 

 base of the stem. In some advanced case* 



