62 



THE AGRICULTURAL NEWS 



Februaey 24, 1917. 



FUNGUS NOTES. 



^HE RIND FUNGUS OF SUGAR-CANE. 



In Vol. I No. 1 of the Journal of the Board of Gom- 

 vdssioners of Agriculture, Porto Rico, Mr. J. R. Johnston, 

 formerly pathologist of the Insular E.xperiment Station, 

 ■<iiscusse.s the history and cause of the so-called rind disease. 

 The subject is one which has been exceptionally fruitful in 

 siiisunderstandings, and the records of old mistakes still 

 •confuse issues which in themselves should now be fairly clear. 



As to the actual position of the fungu.s Melanronium 

 ■sicchari'm sugarcane pathology, there is now probably little 

 «s=ential difference of opinion. The account given by John- 

 ston attributes more damage to the action of this fungus 

 than experience in the Lesser Antilles would be held to 

 ju.stify, but this is probably due for the most part to 

 differences in agricultural practice. In some parts of 

 fit. Kitis, where owing to the small capacity of the 

 aiiuscovado works cane is often left standing longer 

 than in the general custom in these islands, infestations 

 «uch as those described by Johnston have several times been 

 noticed. Experience here further coincides with Johnston's 

 conclusions that the fungus occurs on green cane only in 

 shoots injured or killed by Marasmius or by insects, and in 

 such circumstances can hardly be considered as more than 

 .saprophytic. At a later stage the rotting back of certain 

 varieties is .said to be not uncommon in Porto Rico, and is 

 ■attributed primarily to a weakened condition brought on by 

 poor soil or climatic influences, which leads to infestation with 

 the fungus. The latter, by rotting down the canes to which 

 «,ccess is thus opened renders recovery impossible. The 

 -conditions are admittedly not clear, and it cannot be .said 

 that damage of this type has been definitely recog- 

 nized by the mycologists of this Department. This niay be 

 •due to a disposition to regard all such occurrences as due to 

 infestation with red rot (Colhtrotric/ium falratuitt), with 

 Melanconium as a universal scavenger following close behind. 



The mention of red rot brings this review to the point 

 where some exception must be taken to Johnston's attitude. 

 After re-traversing the now familiar ground of the synonymy 

 rA Melanconium sacchari and the confusion introduced into 

 the study of sugarcane diseases by Massees illconsidered 

 pronouncements, he criticises somewhat severely the conclu- 

 •sions of Howard in attributing rind disease primarily to 

 Collet otriclium falcatutn. The point m>ty be at once ronced- 

 ■ed that rind disease received its name from the appearance 

 caused hy MelanconiwH. sacchari, and if the name be restricted, 

 as it is by Johnston, to the effects produced by that fungus, 

 then Howard's work mainly cunccrns a dift'erent subject al- 

 together, which is Johnston's contention. He remarks: 

 '[Howard) has selected certain symptoms of disease in the 

 plant . . . and has then concluded that the fungus he is dealing 

 ■with is the cause of the rind disease, .disregarding the fact 

 that neither the symptoms nor the fungus have much to do 

 »vith the rind and have notliing whatever to do with 



the eruptions on the rind.' This is little more than a dispute 

 about a popular name. Using the term rind disease at its 

 face value, Colletotrichura may have nothing to do with it; 

 using it in its historical sense, it had almost everything. The 

 real startinji point of the whole business of rind disease was- 

 the occurrence well known and deeply remembered throughout 

 the British West Indies as the breakdown of the liourbon 

 cane. There were no plant pathologists in the West Indies 

 in those days, and few planters had ever heard of a fungus. 

 The trouble was first attributed to the .shot-borer beetle, the 

 association of which with the affected canes was plain to be 

 seen. When the idea of a fungus became more familiar, the 

 presence of Melanconium was similarly obvious, and belief in 

 its association with the disease was confirmed by the conclusions 

 of Massee. The terms rind disease and rind fungus were at 

 that stage perfectly appropriate, and were u-sed in reference 

 to the disease, be its cause what it might, which was 

 threatening to wipe the sugar industry out of existence. 

 It is to the work of Howard, applying the discoveries 

 of the Java pathologists to the West Indies, that we 

 owe the recognition of the epidemic as due to the obscure, 

 but potent infestation of the Bourbon with the red rot fungus. 

 The statement that tliis was the cause of rind disease conveyed 

 an accurate enough meaning to those whom it most concerned. 

 Further, the remark that Colletotrichura had 'nothing what- 

 ever to do with the eruptions on the rind' will certainly not 

 bear literal interpretation. That fungus was killing out canes 

 by the acre, and everyone of these canes, as present experience 

 shows, would become thoroughly infested with Melanconium. 

 With the adoption of resistant varieties, shot borer has almost 

 disappeared and Melanconium has .sunk back to the position 

 outlined in the earlier part of this review, but at that time it 

 must have been almost a prominent object in the landscape. 



This reversion to history was necessary in vindication 

 of Howard's usage of the terra, but the confusion that its use' 

 has continued to cause has led to the very geniTal adoption oi 

 the name red rot for C'olletotrichum disease, and in the publi- 

 cations of this Department the term rind fungus is now 

 restricted, as logic demands, to Melanconium sacchari. 



W.N. 



West Indian Food Supply— A*i<!«e for Decem- 

 ber 7, 1916, the leading English scientific journal, reproduces 

 the principal facts brought forward editorially in the Agricul- 

 tural A'ew.'i, for October 21, on the subject of the eU'ect of the 

 rise in the price of Hour upon the local food supply in the 

 West Indies. It is stated: 'The failure of the North 

 American wheat crop this year is causing some anxiety in 

 the West Indies, as the islands rely entirely on this source 

 of supply. It seems doubtful if the usual quantities of 

 flour will be available, and the question of possible substi- 

 tutes is receiving (..tficial attention. The Agricultural News 

 (Barbados) of October 21 suggests that the cultivation of 

 maize, tiuinea corn, cassava, and sweet potatoes should be 

 extended. All these foodstuffs are already grown in tho 

 islands, but in contrast to the important cereals, none of 

 them will keep without special precaution; the sweet potato, 

 the principal vegetable of the people, is particularly perish- 

 able. As regards corn, the difficulty can be overcome by 

 drying, and the Governments of Antigua and St. Vincent 

 have established kiln driers working on a co-operative basis. 

 If the shortage of wheat flour should become seriou.s, the 

 rice crop of British Guiana will have to be drawn on to a 

 greater extent than it is already, aud the cultivation of this 

 cereal, which is at present a large industry in Trinidad, may 

 be further developed.' 



