42 



N. S. ENTOMOLOGICAL SOCIETY. 



of Wagner app'e trees sprayed with varying strengths of barium tetrasulphide (B.T.S.) 

 with f lb. arsenate of lime in each are interesting. 



Arsenate of lime I lb 



B.T.S, 



3f lb 

 3 



2\ 

 2 



u 



Percentage of leaf 

 injury estimated 

 Aug. 8, '16. 



to 40 gals. 



10 



none 



5 



10 



15 



While these results were obtained from experiments conducted on a very small scale, 

 and though the varying percentage of leaf injury was noticeable when the results were 

 being taken in the field, they still indicate what other field observations show, that with 

 excessively dilute fungicide solutions or alone arsenate of lime is highly dangerous to 

 foliage, but, in some manner, normal solutions of lime sulphur, barium tetrasulphide 

 (B T.S.) Bordeaux and, to a great extent, solutions of sodium sulphide (soluble sul- 

 phur), protect arsenate of lime from the carbon dioxide of the air and so reduce or pre- 

 vent injury from it. 



EFFECT WITH OTHER SULPHIDE SOLUTIONS. 



The arsenate of lime, as noted before, causes no chemical change in sulphide solu- 

 tions whereas arsenate of lead invariably has a very serious effect. 



Barium tetrasulphide (B.T.S.) is a dry powdered sulphide, which may be ob- 

 tained by coking barytes, washing and filtering the coke, boiling the filtrate with free 

 sulphur and drying. With this compound lead arsenate give? a marked reaction, with 

 the rapid formation of lead sulphide. Arsenate of lime with barium tetrasulphide 

 causes no reaction. The following percentages of leaf injury were obtained on July 17th 

 from the poisons in combination with barium tetrasulphide after three applications of 

 spray. 



Dry (acid) lead arsenate 1 lb. to 40 gals, barium tetrasulphide 3 lbs. to 40 gals; 50 

 per cent of the leaves burned slightly. 



Dry arsenate of lime f lb. to 40 gals., barium tetrasulphide 3 lbs. to 40 gals., 2 per 

 cent of the leaves burned slightly. 



As with lime and sulphur, lead arsenate breaking up the barium tetrasulphide 

 makes the spray more unsafe than where arsenate of lime is used. 



The effects of arsenate of lead when used with sodium sulphide (Soluble sulphur) 

 are so well known to the fruit-growing public that they need but little comment. As 

 a rule this combination resulted in burning all the leaves, more or less, causing a por- 

 tion of them to drop from the trees. In some cases the burning was not so severe as in- 

 dicated. With mixed lead arsenates (acid and tri-plumbic) or with tri-plumbic lead ar- 

 senate the burning was usually not so severe as with hydrogen or acid lead arsenate. 



In two instances in the Annapolis Valley growers added lead arsenate to the sodium 

 sulphide and sprayed a portion of the tank on immediately, and on account of trouble 

 with the outfit did not apply the remainder till the following day. The burning in both 

 cases was more severe where the combination was allowed to stand than where applied 



