182 



THE AGRICULTURAL NEWS. 



CONFERENCE OF COTTON GROWERS AT BARBADOS. 



June 13, 1908. 



(Continued from last issue of the A<jrl<-uUa)-al iTefrs.) 



Mr. F. A. Stockdale, B.A., F.L.S., M.\eoli)s;i.st on 

 the staff of the Imperial ])epartmeiit of Agricnlt.nre, 

 read a paper on the fungus diseases of cotton »\\A their 

 treatment. 



Cotton in Barbados had suffered but sliyhtly fiom 

 fungus di.seases during the past two seasons, t^ut constant 

 watchfuhies.s and prompt appHcation of remedial nieasure.s 

 were necessary. 



Anthracnose or ' pink spot ' had formerly cau.sed a certain 

 amount of damage to the cotton croii. 8poi-cs of the fungus, 

 carried on cotton seed, have frequently been the means of 

 spreading the disease. The disinfection of the cotton seed, by 

 steepin" it for twenty minutes in a solution of 1 part of 

 corrosive sublimate in 1,000 pails of water (1 oz. of corrosive 

 jiubliniate in 7 gallons of water) forms a safe way of destroy- 

 ing the fungus without injuring the germinating power of the 

 cotton .seed itself. 



Mildew is probably the mos-t common of leaf diseases of 

 cotton at Barbado.s, and is the only one which has caused any 

 considerable damage during the past season. When cotton 

 plants are attacked by mildew it is observed that the ujiper 

 surfaces of the leaves turn reddish-biown in irregular areas, 

 while the under .sides of the disea.sed leaves become covered 

 with a white, glistening felt of fungus In phae. Spores of the 

 fungus are produced externally, and these ;ire WMslied about 

 by rain, and also distributed by wind. Mildew most 

 frequently makes its appearance on leaves of plants 

 that have passed their prime, and towards the end of the 

 season when the cotton ]ilants are in less vigorous growth. 

 Injured spots on the surface of the leaf form a favourable 

 ■iipportunity for attack, which probably iiccounts for the 

 frequency with which mildew follows an attack of aphides. In 

 view of the los.ses of leaves and bolls ri'sulting from attacks 

 ■of this fungus, it is evident that the time has arrived when 

 steps should be taken to prevent the disease from becoming 

 a further source of trouble. Experiments as to the best 

 means of controlling the fungus have been connnenced at 

 Barbados. Spraying with Bordeaux mixture, or dusting with 

 .sul[>hur and lime, should keep nnldew in check. 



Increasing attention is now being given to siiiaying as 

 a means of controlling insect ])ests, and it is possilile that 

 further experiments may show that various mixtures can be 

 utilized for spraying iiur|(Osps whii-h will give etl'e<-tive 

 results as fungicides us well as in.secticides. I'.ordeaux 

 iinxture and Paris gre<Mi may be used in combination, and 

 possibly some material might be mixed with lead arst-nate, 

 which woidd make it etlective as u fungicide, in addition 

 to its value for insecticide i)niposes. 



The planters of the island were a^ked to co opciate 

 with the otticers of the Depaitment in carrying on trials for 

 the purpose of ascertaining the mo.st econonii(!al nietlioil of 

 i-ombating insect pests, and at the same time of preM'iit- 

 ing the appearance or si)rcad of fungus parasites, .\ttai-ks of 

 aphis and bad attacks of nnldew not infi'eqnerilly occur on 

 tlie .same crop of cotton, and tlieicfoic tii.ds .■■hould be iiumIc 

 to discover some method of irralinrnl cipially etlt'rti\c 

 ;igainst both. 



Mr. H. A. r.alhni, M.Se., Eiitoiiiolooist on the staft 

 of the Imperial Department of Agriculture, read 

 ;i paper which gave particulars of the insect pests 

 affecting cotton in Barbados during IftOT-S. 



The cotton worm was fairly aliundant thr(.iughovit the 

 sea.son, and se^■eral seVere attacks were experienced. The 

 application of Paris green and lime, howe\er, at the rate of 

 1 part of Paris green ti^' 6 parts of lime, gave good results- 

 in keeping the worm in check. The occurrence of frequent 

 .showers of rain had at times made repeated applications 

 nece.ssary, and some planters lielieve that the krge amount* 

 used have injured the leaves of the cotton plants. .Spraying 

 with lead arsenate is also reported t(j have been satisfactoi-y 

 for this puriiose. '' 



It is expected that during the conung season, spraying 

 will lie practised on several estates in Barbados for the 

 control ot the cotton worm. Paris green and lead arsenate 

 are the insecticides to be used. 



Neither the red maggot nor the cutworm has done 

 nmch damage at liarbados during the year, but aphis lias 

 been very abundant in certain localities. An etl'ecti\e method 

 of treatment for attack by (-utworm consists in the use\o{ 

 a mixture of bran, molasses, and Paris green. 



The lady birds and the lace-wing fly, though abundant 

 in most parts of the island aie lacking in others, or at least 

 are not sutticiently nuineruus to C(.introl the ajihisand prevent 

 damage by their attacl^. The mixture (Paris green and lime) 

 used fur tlie cotton worm has been .said to kill, by contact, 

 the larvae of these beneficial insects. The difference in the 

 number of lady-birds and laci-wing flies that is evident in 

 various districts of the island, however, does not lend supi)ort 

 to this statement, since the use of Paris green and lime 

 is general, and if it killed bcneiicial insects in one locality 

 it woidd do so in all. 



Spraying with kerosene emubion Ins been successful in 

 controlling the cotton a])his in one of the Northern Islands. 

 This treatment can be carried out at low cost. 



One of the most tioublesome of the insect pests of cotton 

 is the hibi.scus (or black i .scale. This scale in.sect attacks not 

 only the cotton [ilaiits, but even weeds- growing wild in the 

 fielils. Prevention is the best method of treatment in the 

 iMse of this i)est. Estate owners should see that all old 

 cotton is destroyed some time before the planting of the new 

 (■ro|i Planters "on adjoining estates .should, if possible, so 

 arraime the time of clearing old cotton and ])laiiting the new 

 crop, that there .should be no cotton standing on their estate* 

 for a miinler of weeks. Wild plants, growing in pastures, 

 gullies, etc., which harbour this scale insect, .should be 

 destroyed. 



A parasite of the black scale was 

 which is now doing excellent work 

 ^cale insect in check in P.arbados, 

 probably increase in number. When 

 jiulled, it ought to be left in the fiehl 

 order to give a greater number of the parasites an opportun- 

 ity to mature and escape. The white' .scale is not often 

 a serious pest, but is very troublesome at time.s. Thi 

 also has its parasites, which have been found in llarbi 

 the first time within 'the |)ast tew days. 



Spraying to control scale insects on cotton plants may 

 become necessary, but cle*in. cultural methods, such as the 

 destruction of old cotton some time before planting the new 

 crop, the destruction of wild or useless plants harbouring the 

 siales, and i-lean weeding in the fields, should jjrove sufKcient, 

 together with the beneficial work of the iiarasites mentiouecl. 



discovered last year, 

 towards keeping thi.s 

 and the parasite will 

 old cotton i.s cut f)r 

 for a week or so, in 



s insect 

 idos for 



