05-4 ANNUAL ItKl'OUT UK THE • Ofif. Doc. 



RECENT ADVANCES IN OUR KNOWLEDGE OF LIME- 

 SULPHUR 



By J. V. STEWART, Experimental Horticulture, State College, Pa. 



Owing to the increasing interest in the subject, 1 have been 

 asked again to run over the details of making concentrated lime- 

 sulphur. Details are hard to remember, however, and since they 

 are already available for the asking in our Bulletin i)IJ, it has seemed 

 to me wiser to deal here with some of the more general phases of the 

 subject, presenting rather the principles upon which the details de- 

 pend. In doing this, it has seemed best to trace out the develop- 

 ment somewhat along historical lines, adding briefly in their proper 

 places those features of most importance that we have learned dur- 

 ing the past year. 



As we have noted before, the career of lime-sulphur as a spray 

 material has been rather checkered. Starting in 1886 at Fresno, 

 Cal., when a Mr. Dusey borrowed a pail full of sheep dip from his 

 neighbor, Covell, thinking that if it killed the lice on sheep it ought 

 also to do it on trees, it speedily became the leading contact insect- 

 icide throughout the Pacific Coast. It was then brought East in 

 1894, soon after the discovery of scale in Virginia, was tried in 

 Maryland, and discarded, being found apparently useless under east- 

 ern conditions. It was partially revived by Marlatt in 1900, but 

 failed to secure wide acceptance until after the work of Forbes 

 and others in 1902. From the latter date until approximately 1909, 

 it remained the standard insecticide throughout the country, in 

 spite of its many objectionable and disagreeable features. This 

 was the old, home-boiled, dilute mixture which finally came to be 

 made by using 15 or 20 pounds of lime and 15 pounds of sulphur to 

 50 gallons of total product. 



While this development was taking place in the dilute mixture, 

 another preparation, without the objectionable features, was grad- 

 ually coming to the front. This was the so-called commercial or 

 factorj-boiled lime-sulphur. It Avas storable, free from sediment, 

 easily applied, and though much denser than the home niatie prej)- 

 aration, it was practically free from crystals. Just when and by 

 whom it was first used as an insecticide, I have been unable to dis- 

 cover. It appears, however, that along in 1902 or 1903, a Stock 

 Food Company of Omaha learned that some of their patrons in 

 Utah were buA'ing a few extra barrels of a concentrated cattle-dip 

 for application to trees. Later inquiries and tests showed the value 

 of this, and from that beginning has developed the present remark- 

 able production of commercial lime-sulphur materials. Both types 

 of lime-sulphur insecticides, therefore, came into use rather acci- 

 dentally and apparentlj^ independently, as the result of a transfer in 

 use from dip preparations. 



