.■)C2 .loiK-NAi. OF riiK l)i;i'.\in Mi:.\i- ok A(.iti( i i;i i uk. — Oct., 1922. 



iuforior lo tlio load arsniale. and failed to adhere well to tolia;^*' and 

 liui'i. A later iiiaiiu lact ured iniproNed nuiteii.il may possiUly ^i\-e 

 hettei- results. No hurninu' ;)t toliaye or fruit was exi)erieueed . 



Caleiuiu arsenate is soniewliat (dieaper than lea<l arsenate, pound 

 tor pound, and wiien used at the rate of j lb. in 40 imperial gallons 

 of water, is consideral)ly cheaper than lead arsenate as a spray. In 

 Xova vScotia it is said to be used in the orchard districts almost to the 

 exclusion of lead arsenate. It is extensively used in the southern 

 part of the United States as a dust for the control of cotton insects. 

 Uefore it can be recommended to the fruit grower in South Africa, 

 much better results under South Afri( an conditions must lie obtained. 



The Lnfmi:n(I': of JiiMK-si i.nii i; and Uou'divm x Mi.mthk on thk 



P;FF1(IE.N( V OF liKAl) AkSK.NATF. 



IJattail, a French scientist, in a paper on " The Causes which 

 afiect the Toxicity of Arsenicals employed in Agriculture," states: 

 " The addition of these arsenicals to liordeaux mixture with the idea 

 of producing a cond)ination spray against both insects and mildew, 

 reduces the efl^ectiveness of the arsenicals by 50 per cent., and it is 

 a matter of common complaint that these mixed sprays are not 

 effective. " (2) Sanders, of Canada, (3) states : " Lime-sulphur reduces 

 the killing value of arsenical poisons by 20 per cent.; bordeauK ly 

 44 per cent.'' Robinson of the United States (4) states: "When 

 lime-sulphur is mixed with the acid forrii of lead arsenate (the form 

 that must be used for satisfactory control of codling'), the efficiency of 

 the spray is decreased by about .")') ])er cent." 



The results of experiments carried out at Elsenburg for the last 

 two years to determine this question, clearly indicate that neither 

 lime-sulphur nor bordeaux, wjien used ns a combination spray with 

 lead arsenate, at the concentration usually" ad^'ised, destroy the effici- 

 ency of lead arsenate ir. codling-control any more than from 1 to o per 

 cent. It a])])ea]s that an increase from I5 lb. of lead arsenate jio^der 

 to ll 11). in 40 imperial gallons of water prevents .sJightly the inlluence 

 of the fungicides on the efficieiu y of lead arsenate, but not sufficiently 

 to wairant tins increase in concentration. The tiuit grower is 

 therefore advised to continue using a fungicide with lead arsenate, 

 when circumstances warrant its employment, aud at no less concentra- 

 tion than 1] lb. of lead arsenate jxn^der oi' 2^ lb. of paste in 40 

 iriiperial gallons of diluted boideaux or lime sulphur. A weaker solu- 

 ti(m than this would not g*ive as satisfactory eontrol of the insect 

 according to results obtained in 1919-20 (5). 



Thk IXFLIJENCE OF CaI,( ILM CaSI'.KNATE Sl'l!EAI)i:u 0.\ TJIE EFFICIENCY 



OF Leau Arsf:xat]:. 



Many attemi)ts have been made by scientists to improve the 

 spreading of common insecticides and fungicides in water over foliage 

 and fruit, as well as the ability of such solutions to stick to the 

 surface. Lead arsenate is not an ideal insecticide in several lespects. 

 It does not remain in suspension in water very long*, and theieiore 

 must be constantly stirred in the spray tank during spraying- opeia- 

 tions. This is a serious failing- in Soutli Afiica, where many hand- 

 pumps are used, which necessitates constant watching- of the native 



