Vol. SVin. No. i:iO. 



THE AGUlUUL'ltJRAL NEWS. 



GS 



average of two countings of each lot was as follows: lots 

 1, -2, and 4, 100; h.l 3, Uo; lot -5. V8; lot G, 99. 



(7) Tbe di-ea.se spieaJs soneiiiii-s slovviy, at other 

 times wiih rapidity, but it alw.tys spreads. 



Ill the already iii ntioned e.'«periiiieiil in Eliwaii, 12 per 

 •cent, of the Leilthy cines became diseiseit d'jriiig their 

 growth. Ill aiio. her expeiiiiieiit luide iu Java, ihe diseased 

 pltuts were counted twice on December "2 and on February 

 16. It appeared ilut in December the di-'eas-e was encoun- 

 tered at tiie beginiiins; of i s g'owil), and in Febma/y an 

 important increase of diseased plaols was observed, rising in 

 •caoes to 25 per rent. 



(8) Tde disease is not in the soil; so that the mere 

 fact that a field has conta ned diseised cane has no indaen'^e 

 on the greater or less infection of a subsequent plantioi;. 



In Java the following ^e^ull3 were obtained in planting 

 the variety G.Z. 217; (I) in soil wh.ch hid held dise«sed 

 •cane, (2i in soil whi-h hal been occupied by hea'lhy cane, 

 and i3) in soil wliich h-id never befo e been planted in cane. 

 The percentage of diseased plants w is calculated on the total 

 Aumber of plants in the p'ot. At the Hrstc itting the percen- 

 tage on soil which hai borne previ .nsly heilthy cines was 

 .2-6; on soil which had borne diseased cane, 3-6; OD soil which 

 had never been planted in cane, 3 3. At the aeconil couoiing 

 the percentage was rt^spective y 2r2"', 22'3-">, and 16-47. 



At Ceiitial Fajaido the varieties Yellow Ciedonia, 

 D. 4-18, D, 433, Sir pad, and B 3112 were planted July 31, 

 1918, in holes from which disea-jed cane h»d j i-t been cut. 

 On September 18, not one of the new sho its were diseased. 



(9) Approximately the disease is wide.^pread in the cane 

 plantations of Porto Hico situated lotbe west of an imaginary 

 line drawn from Biyaraon in the north to Ginicaia the 

 south. To the east of this line only a few diseased stalks are 

 met with on isolated plantations. 



ERADICATION OF THE DISEASE. 



The 'mosaic disease,' also known as the 'mottling disease, 

 the 'Arecibo disease,' and the 'dog bite disease' is the same 

 ■disease which attacks canes in Java and Htwaii, and which is 

 known there as the 'yellow stiip-^ disease.' This disease of 

 'the sugar cane is an infection which is transmitted in plantings 

 ciade with infested cuttings. There also exists a secondary 

 infection by which healihy plants can be rendered diseased at 

 any stage of their growth. Probably this infection is carried 

 by insects. The disease is not transmitted in the soil. 

 Soils are not rendered infectious by the growth of dis^eased 

 cane on them. Tue pre.-ence or absence of the disease depends 

 ia no degree on the kind of soil, or its preparation, or of 

 the kind of manure employed on it. 



This disease is incurable. A diseased plant remains in 

 that condition; it may live many years, bat its i^rowth will 

 ■always be slow, and its production much reduced. To eradi- 

 Cite this disease it is necessary to employ for planting only 

 healthy and resistant cuttings. As far as possible, infected 

 plants in neighbouring fif Ids ought to be rooted up and des- 

 tioyed, in order thus to aihieve the elimination of contagion 

 and to avoid a secondary infection. In districts widely 

 infected, cuttings free from the disease will be obtained wi'.h 

 diflBculty. In the majority of Cises it would be necessary to 

 import cuttings froia other districts where there are no indi- 

 cations of the disease. That might he very expensive, and it 

 would practically be pref< rable to oultivaie sp-citl plots with 

 e utings carefully selected, to be used as nurseries for successive 

 plantings. The cuttings for such nurseries ought to be 

 selected while the cune remains growing in ihe field. As 

 soon as the leaves begin to fall it is very difficult to distin- 

 guish a diseased plant from a Ltaltby one. 



By chance some heilthy plants miy be seen in fields- 

 most conspicno isly infected. These instances are entirely 

 accidenial, biit d)ubtles^ they repres3nt a greater or less 

 iuimuniiy to the disease. 



The best of these healthy canes in fields badly infected 

 ought to be selected and •.■.jcd f ji" iua p..;,:;.;-.!^ ol u.;..,..;-.-^ 

 for s ipplying o'.lier-*, and for the cuttings for the ne«t planting. 

 Such nurseries ought to be located as fir as possible from tho 

 fields where diseased cmes have been planted, and to wind- 

 ward of such fields. When the cuttings have geruiiuated iha 

 n-irseries ought to be carefully inspected, and dis3a:cd c-.ittiags 

 which iniy have been accidentally planted ought to be rooted 

 out. Tnese in.'pections should be continued, if possible, every 

 two wee^s during the period of growth, for the purpose of 

 diicovering aid eradicating every cise oj secondiry infection 

 whici miy appear. If attention is devoted to carry this 

 out carefull'-, a nursery of absolutely healthy canes will be 

 obuined which will assure health of the next planting. The 

 plots f.ir the ab-jve mentioned nurseries ought to be 

 prep ir d close together, to the windward of the plantation. 

 They o'ght not to be dispersed among fields of infected 

 cane. They ought to be inspected frequently in order to bo 

 sure that all second iry infections may be immediately noticed. 



If these directions are followed rigidly aad completely, 

 an entire district can be freed from this dis93,33 in the short 

 ppice of two or three years. There are only two things to be 

 done, and the one is as important as the other: 



(1) Always plant the healthiest cuttings which cau be 

 obtained. Never plant infected cuttings, and the propaga- 

 tion of the disease will be controlled. 



(2) Inspect the fields freq-iently. Eradicite the contam- 

 inated cuttings sown accidentally, and keep a watch for cases 

 of secondary infection. 



In order to control the disease, it is necessary to 

 destroy the source of infection. Aa the infec ion is not in 

 the soil, the problem is simplified; attention must be focussod 

 on the plant. As the disease is traasmissible, diseased 

 cuttings must not be planted. As the disease is widespread 

 to the west of the im-^iginiry line from Biyamon to Guaaicfa, 

 care must be taken not to use cuttings from that region. Ia 

 order to avoid the use of doubtful plants, cuttings ought to 

 be made while the cane is in growth. As the diccase is prop»« 

 gated from diseased plants to healthy plants, tho fields must 

 be inspec ed continually, the diseased plants eradicated and 

 burnt, and fresh cuttings supplied, since it is conceded that the 

 infection is not in the soil. As the mottling dise-ase is mora 

 easily distinguished in young plants, and as at this period 

 there is opportunity for replanting, examiaatio-u should always 

 be made preferably of the young plants- 



In order to offset as much as possible the financial 

 losses sustained lately in coauexion with their coffee planta- 

 tions, the planters in Soutliern Brazil are busily engaged in 

 arranging for planting cotton instead, the pric?.' now obtained 

 for this product maintaining at present a continu.il upward 

 tendency. Enormous trac'.s of Isnd in Sao i'a'ilo .ird neigh- 

 bouring districts are suitable for cotton grovrine, and there 

 is evr-ry reason to believe that the prodcctiou of this article 

 during the next yt-ar or two will amount to unprecedented 

 quantities. That this will oauso a great roductiou in the 

 present quota'ions there is no doubt, but what is doubtful is 

 whether the price will d-soend lowenotigh to aJiojF for cxpjr- 

 taiions to f^irei^'D countriv.", such as Great Britain. In that 

 cise the only outlet will bo to sell to the national weaving 

 mills. (The Clumber nf Commerce Journal, Deoember 191S.J 



