87 



satisfactory. The amount commonly recommentled is one 

 pint of nicotine solution (forty percent) to one hundred 

 gallons of Avater. The addition of three to five pounds of 

 !^"oap enhances the adhesive and spreading properties of the 

 s}>ray. If the insects are not numerous the nicotine solu- 

 tion without the soap may be added to lime-sulphur solution 

 and arsenate of lead, forming a "three-in-one" mixture. 

 Thorough applications should be made just Ijefore the 

 llossoms open and after the petals have fallen. 



Defects of an entirely different character to the fore- 

 going are large, irregular cavities in young apples which, 

 in healing, form yellowish or brownish corky patches or 

 areas in the mature fruit. These are the result of the ac- 

 tivities of various caterpillars known as leaf-rollers, green 

 fruit-worms, tussock moth and the palmer worm. The 

 fruit-tree leaf-roller especially has in certain communities 

 <(one much damage to the crops of some orchards. 



THE INSECTICIDAL PROPERTIES OF VARIOUS 

 SULPHIDES AND POLYSULPHIDES 

 Recent years have witnessed the appearance on the 

 rsjarket of a large number of spraying mixtures which derive 

 their efficient properties from sulphides and polysulphides 

 cf sodium, potassium calcium and barium. Most of these 

 are in liquid form, but preparations in a powdered or gran- 

 ular state, containing sulphides of the foregoing bases, are 

 offered for sale or can be obtained for experimental pur- 

 I'Oses. The amount of sulphur^ in proprietary insecticif^'^s 

 containing sulphides and polysulphides of the different bases 

 varies greatly, ranging for the sodium preparations from 

 1.79 to 58.92 per cent; potassium, 2. .39 to 38.72 per cent; 

 calcium, 3.97 to 26.40 per cent, and barium 16.54 to 44.0 

 per cent. 



The variation in amounts of sulphur in the commercial 

 mixtures reveals a need of definite information as to the 

 comparative insecticidal properties of the foregoing sul- 

 phides as a basis for safe and specific recommendations. To 

 obtain data as to the relative merits, experiments have been 



