356 



Ufeniece (N.)- OnbiTii opraHHsai^'m OTpnAa paGoMMXii no 6opb6t 

 C"b BpeflMTeJlflMH LlHTpycOB'b B"b 1915 r. [An Experiment in 

 organising Gangs of Workmen for the Control of Pests of Citrus 

 Trees in 1915.— «PycCKie Cy6TponMKM.» [Russian Suhtropks], 

 Batum, no. 11-12, 1916, pp. 29-72. [Received 18th June 1917.] 



This paper describes fully the work carried out by a sub-committee 

 of the Batum Agricultural Society entrusted with the conduct of the 

 campaign against pests of citrus trees in the spring of 1915. A special 

 gang of workmen was organised by the owners of the orchards in the 

 locality at their own expense, the instructor of the Society being 

 responsible for the general supervision of the work, which consisted of 

 thinning the crowns of the trees and spraying wnth various insecticides. 

 Over 30,000 trees were sprayed during the summer, at a cost of about 

 £80. The principal insecticides used were carbolic emulsion, Scalecide, 

 tobacco-lye emulsion, kerosene-carbolic emulsion and lime-sulphur. 



Carbolic emulsion was prepared to contain from TG to 2 per cent, 

 of carbolic acid and from TS to 2 per cent, of soft soap ; in some cases 

 scorching of the fruit occurred, owing to the variable quality of crude 

 carbolic acid available ; its application therefore requires great 

 caution, especially in summer. 



Kerosene emulsion contained 5% kerosene, and from '5 to 1"3% 

 soft soap ; it requires constant stirring, otherwise the kerosene rises 

 to the surface ; it spreads easily over the tree and penetrates into all 

 the cracks of the bark, but flows down the leaves and trunk, which 

 may result in injury to the roots. 



Carbolic-kerosene emulsion was composed of 5 per cent, kerosene, 

 1*7 per cent, soft soap and from r5 to 2 per cent, carbolic acid ; the 

 last-named being added to the mixture of kerosene and soap ; this 

 compound is more homogeneous, being lighter than carbolic emulsion, 

 but heavier and less volatile than kerosene and is very stable, keeping 

 for a long time. This emulsion, with from 0"88 to r66% hemp oil 

 added, as recommended by Prof. Cholodkovsky, is more effective 

 against scale-insects. 



Scalecide, which is a ready-made product, was used at a strength of 

 10% in summer and 20% in winter and is, w^hen fresh, very effective 

 and harmless to the plants, its only disadvantage being its high price. 



Tobacco-lye emulsion is composed of 1*66 to 3*33% tobacco 

 extract and 1'66% soft soap in 100 parts of the liquid prepared by 

 boiling dry wood-ashes in three times their volume of water for about 

 one hour. This liquid should be tested before use for scorching and 

 further diluted, if necessary ; it requires constant stirring and careful 

 preparation to avoid choking the nozzle. 



Lime-sulphur, when used in summer, contained 2% flowers of 

 sulphur and 3% quick lime ; for winter use the proportion was 3% 

 sulphur and 4 '6% lime. 



Soda-naphtha emulsion (Woburn mixture) was prepared either of 

 3'33% naphtha or kerosene, 0-88% soft soap and 2*1% caustic soda, 

 or of 5% naphtha or kerosene, 0-83% soft soap, 7'43% carbonate of 

 soda and 2*03% quick lime ; the last mixture is very unstable and 

 requires constant stirring. 



Tobacco extract emulsion consisted of 2 '66% tobacco extract and 

 0-83% soft soap. 



