174 



The Supplement to the Tropical Agriculturist 



all the cases which I have seen the cement 

 has dried into a compact mass quite free 

 from the wood. In such a condition it can- 

 not add anything to the strength of the tree ; 

 and the rain water which lodges behind the 

 cement soon induces decay. It is better to 

 slope the lower edge of the hole so that rain 

 water will not lodge, and to leave the hole open. 



Though the prescribed treatment has been 

 adopted, there have been many suggestions that 

 it ought to be possible to discover some more 

 conservative treatment, i.e., some method which 

 does not involve excision of the diseased tissue. 

 Needless to say, no hope of such a treatment 

 has ever been held out. The idea which under- 

 lies these suggestions in every case is that it 

 should be possible to water the roots of the 

 tree with some solution which will eradicate 

 the fungus without injuring the tree. Such 

 an idea has not escaped the imagination of 

 mycologists ; but in spite of many years of ex- 

 periment, the internal application of fungicides 

 has not met with the slightest success, whether 

 they have been applied as liquids to the roots or 

 as liquids or solids in holes in the stem. In the 

 present case 



ANY SUBSTANCE WHICH WOULD KILL THE FUNGUS 

 WOULD UNDOUBTEDLY KILL THE TKEE IF 

 APPLIED TO THE ROOTS, 



or would locally kill it if inserted in healthy 

 tissues. Moreover, even if it killed the fungus 

 without damaging the healthy tissue, there 

 would be left a mass of decayed tissue within 

 the stem, to act as a nidus for other fungi when 

 the fungicide had disappeared. It is impos- 

 sible to convert the diseased tissue into sound 

 tissue again, though such a claim has been 

 recently made in Ceylon. Further, if the fungi- 

 cide is inserted into the decayed portion of the 

 stem, it can do very little harm to the fungus, 

 for the bundles which convey liquids up the 

 stem are here interrupted, so that it can only 

 penetrate the wet rotting mass by diffusion ; 

 and that process is so slow that the fungicide 

 would never overtake the advancing fungus. 



Further suggestions which have been made for 

 treatment of the bleeding disease will be consi- 

 dered later. -Peradeniya Circular, Vol. IV, ]So. 2'J. 



The long expected Peradeniya Gardens circu- 

 lar of Mr. T. Petch, the Government Mycologist, 

 on the subject of the Coconut Bleeding Disease, 

 from which the foregoing is extracted — will 

 be read with considerable interest by a large num- 

 ber of coconut planters. The completeness of its 

 contents will be seen from the following list : — 



Historical and general ; the structure of the co- 

 conut stem; the effect of the disease ; influence 

 on the crop ; the distribution of the disease ; the 

 size of the coconut stem ; the cause of the dis- 

 ease ; the fungus ; the growth of the fungus on 

 coconut tissue ; general biology of the fungus ; 

 effect of various chemicals on the growth of the 

 fungus ; treatment ; methods of infection ; the 

 manufacture of coir ; other causes of bleeding ; 

 suggested causes of the disease; suggested re- 

 medies ; the fungus in other countries ; resistance 

 to disease ; miscellanea ; the use of salt. 



The circular, which makes a record for this 

 publication, numbers no less than 110 pages, 

 and contains eevoral valuable illustrations, the 



first being of a coconut tree which has had 

 bleeding disease on it for more than two years. 

 The second shows the black external patch on 

 the stem, and has a cross section showing de- 

 cayed strands. The third gives a plantation 

 on which the old scars of the bleeding disease 

 are distinctly visible on the trees. The fourth 

 represents a striking specimen of an old scar 

 of the bleeding disease with a fresh patch 

 started near the top. The first two seotions 

 of the circular do not call for much reference 

 or comment ; but the third, on the effect of the 

 disease, is one which will be looked to first 

 and must be studied in detail. Mr. Petch finds 

 it difficult to decide how much of the tapering 

 in the case of poorer trees is due to the effect 

 of age and how much to the wounds conse- 

 quent on dealing with the disease. In the fourth 

 section he finds there is no reason to think 

 that the crop is reduced where the trees have 

 been lightly affected, and the controlling factor 

 in the fluctuations of crops still remains the 

 weather. The section on distribution of the 

 disease will interest proprietors and it will 

 surprise many to learn that the total number 

 of diseased trees reported is no less than 

 208,184, all of which have been treated, with 

 few exceptions, but even this number is doubt- 

 less below the mark. The sixth section on the 

 size of the coconut stem is one partly of aca- 

 demic interest, but the information in it will be 

 useful to any planting up fresh acreages — the 

 advice in planting being to set the nuts close 

 to each other and in a slanting position, trees 

 from these nuts, apparently, not having a 

 swollen base, which is so much waste material. 

 The section on the cause of the disease points 

 to a fungus, known to cause a similar disease 

 in sugar cane, being responsible. It is en- 

 titled "Thielaviopsis ethaceticus." Section eight 

 gives a very scientific account of the fungus 

 and section nine explains the reason why tho 

 fungus grows freely only on the coconut stem, 

 namely, because (ignoring the inflorescence) 

 that is the only tissue containing appreciable 

 quantities of sugar as such. The biology of 

 the fungus is gone into at length and the preli- 

 minary results of experiments still in progress 

 with various chemicals on the fungus growth 

 are presented. It seems to be proved that an 

 immersion of spores of 15 minutes in one per 

 cent of carbolic acid kills them. The most valu- 

 able section is that which deals with treatment 

 of the disease; this we have quoted above. The 

 methods of infection also require careful study 

 even if special coolies cannot be assigned, as 

 advised, to inspection duty only, and for marking 

 diseased trees. No danger, it appears, is to be 

 feared from the manufacture of coir from dis- 

 eased trees. Other causes of bleeding than the 

 fungus are detailed, while still further causes are 

 suggested though not actually proved. The sec- 

 tion dealing with suggested remedies disposes of 

 several which have been accepted hitherto, ex- 

 plaining why they must be discounted and 

 abandoned. The last sections, which are men- 

 tioned above, are perhaps less important but 

 should also be examined to'round off one's know- 

 ledge of the coconut tree. The one on the use of 

 salt summarises the information available from 

 various sources up to date,— T. Peich, b, a., b.sc. 



