C6 



THE AGRICULTUKAL NEWS. 



March 



190S. 



The symptoms of root disease are well known to 

 most sugar planters in the West Indies. The shoots 

 affected present a stunted appearance ; the leaves are 

 few in number and pale-green in colour, while the 

 oldest leaves show a tendency to dry up from the apex 

 and margin. The youngest leaves present infolding of 

 the two halves of the blade, to prevent, as far a^, 

 possible, undue loss of moisture by evaporation. It is 

 characteristic of the disease, too, that the leaf bases 

 at the foot of the cane are matted to the stem by 

 a 'felt' of white mycelium. 



Root disease tends to destroy the cane crop in two 

 ways : it destroys the roots of plants and ratoons, and 

 it also smothers the new shoots of ratoon stools. 



Destruction of the roots is caused by the fungus 

 entering and destroying the delicate cells that consti- 

 tute the gro\^'iiig points. The growth of the root is 

 stopped, and the available supply of water and 

 minerals, etc. in solution, is therefore gradually reduced. 

 The efforts made by the plant to replace the dead or 

 dying roots by new tissue cause a constant drain upon 

 its resources, with the result that the affected cane crop 

 is, at the best, poor and light in character. 



In addition, the matting of the white fungal 

 mycelium undoubtedly smothers or seriousl}' injures 

 young ratoon shoots, and the loss entailed in this way 

 is often very considerable. Young shoots which have 

 died off, too, have sometimes been found to be pene- 

 trated in all directions by a fungus similar in appear- 

 ance to that attacking the roots. 



It may be pointed out that the Marasiulus 

 t-^aevliarl can be distributed in three ways: (1) by 

 spores boriic by the toadstool-like fructifications, (2) by 

 the mycelium that travels undergrouiiil, and (o) by the 

 planting of affected cane cuttings. 



At the late West Indian Agricidtural Conference, 

 the whole question of root disease of the sugar-cane 

 was discussed in a paper prepared by Mr. F. A. Stock- 

 dale, B.A., F.L.S., Mycologist on the staff of the Imper- 

 ial Department of Agriculture. At the beginning of 

 his paper Mr. Stockdale reviewed the advance of knowl- 

 edge that had been made during tiio past ton or 

 twelve years on the subject of root diseases of the 

 sugar-cane. Stress was laid u)miu tho importance of 

 a more thorougli ad<.)])tioii of remedial luoasiirrs with 

 a view of stamping out the disease. 



'I'hc renu'dial and preventive nu'asures rc('on\nien- 

 ded were divided into tJiree classes: (1) cultural 

 improvements, (2) sanitai-y measures, and (.'>) selection 

 of varieties. 



In view of the f;ict that a cane, growing vigorous!)- 

 under iiealthy conditions, is not likely to be seriously 

 attacked by the fungus, the value of thorough and 

 carc'ful cultivation of thesoil becomes at once aijparent, 

 since this tends to allow of good ruot development. 



Ratoons are always much more badly affected by 

 root disease than plant canes, and in fields where the 

 trouble is especially noticeable, it may be better to give 

 up ratooning altogether for a time. 



The importance of good drainage was alluded to, 

 and the question of rotation of crops fully discussed. 

 Sometimes cotton can be grown on the affected land, 

 and in this way a remunerative return can be obtained, 

 at the same time resting the soil from sugar-cane. 



Rotten canes and trash from land where the 

 disease has recently apjieared should never be made 

 into pen manure, but should be destroyed. 



1'he use of lime as a fungicide was also discussed 

 by Jlr. Stockdale, and tho possibility that some of the 

 good results attendant upon the use of lime in many 

 sugar-producing countries might be due to its action 

 on the parasitic enemies of tho cane, rather than its 

 indirect manurial action, was mentioned. Tlie use of 

 lime on sugar lai|ds in Hawaii has recentl}- been on 

 the increase, and in Jamaica it has been shown that 

 lime and cow peas form suitable treatment from 

 a manurial point of view on many sugar-cane soils. 



Another point of groat importance in this connex- 

 ion is the necessity of the greatest care being exercised 

 not to plant cuttings from affected canes. If such 

 cuttings are planted, they obviously serve as centre.s 

 from which the disease is propagated. With suspec- 

 te<l canes, or in planting on soils where disease is likely 

 to occur, the cuttings may with advantage be .soaked 

 in Bordeau.x mixture. 



The disease-resisting i|ualities of nianv ot the 

 seedling canes were referred to by Mr. Stockdale, who 

 i-eportcd that some progress had lately been made in 

 brooding h3brid canes for ilisease resistance. 



I'"inally it was mentioned that the adoption of tlie 

 remedial and ]ir'.venti\e measures described has had 

 such excellent results in Java, where root disease of 

 the sugar-cane was first noticed, that it is now stated 

 to be difficult to liud specimens of the fungus 

 Miira--<in)Hs SiicrlHD'i in the island. The s^-stem of 

 rotation adoptcl, with elimination of ratoon crops, and 

 th(^ great care taken with material for planting purposes 

 have been c.^peci.Hlly iulluontial in bringing about this 

 result. 



