

I 



INTRODUCTION 



The introduction of lime-sulphur spray compound into New York State 

 about the year of 1907 and 1908 caused a great many inquiries as to their var- 

 iation, and value of it as a repression of blister-mite and San Jose scale. How- 

 ever, apparently slight changes in material used or in methods, have resulted 

 in compounds widely different in appearance; spraying qualities, and insect- 

 icidal value or effect. The uncertain tity of securing the best results with the 

 home made mixtures, due to their vaiiiticn, and the unpleasant features con- 

 nected with the making of it at home caused many to welcome the advent of 

 the commercial preparations in concentrated form. The number of brands 

 grew very rapidly due to the marked success of the first, when in 1909 there 

 were at least five on the market. The comparison of the different strengths of 

 the several brands, led to the investigation as to their comparative value. 



So with the advent and marked success of the Lime-sulphur preparation, 

 as a spraying material, for the control of the blistor-mite and San Jose scale 

 the question of combining materials as the Arsenate of Lead and Nic- 

 otine preparations, naturally came to be considered essential, as a saver of time 

 and expense. 



At the suggestion of Professor Cavanaugh, of the Chemistry Department, 

 and Professor Crosby, of the Entomological Department, a chemical study of 

 the reactions with reference to the advisiabilty of mixing Lime-sulphur solu- 

 tion, Lead Arsenate, and Nicotine preparations together for the control of San 

 Jose scale, Red Bugs, etc., by one spraying, was begun, with the results as 

 given in this paper. 



HISTORICAL 



CHEMICAL BASIS OF LIME-SULPHUR PREPARATIONS 



The insecticidal value of these lime-sulphur washes rests, not in any 

 mechanical mixture of the tvo but to the chemical compounds formed by the 

 union of lime or rather calcium and sulphur. In what particular manner the 

 lime sulphur solution acts as an insecticide and fungicide, no one has yet clearly 

 demonstrated. What specific compounds are directly responsible for the eff- 

 ects produced we are not yet certain. If we mix together the two elements in 

 a dry form namely, calcium in the form of lime (CaO) and sulphur they would 

 not combine and would have no effect on each other, but when brought 

 together in a boiling water solution for about forty-five minutes to one hour, 

 they combine to not only form one compound but a series of compounds 

 called calcium polysulphides (CaSx). 



At least two of these compounds are very soluble in water and are very 

 destructive to insect life with which they are brought in contact. There may 

 be formed at least five compounds of calcium and sulphur; since one part of 

 calcium may combine with four-fifths its weight of sulphur, or with two- 

 three, four or five times that amount. The different calcium sulphides in the 



