33 



yoinewhat resembling the down on the seeds of thistles separated out. 

 These were composed of bisulphide of lime (CaS 2 ) aud being freely solu- 

 ble in water, were dissolved when the balance of the water was added. 

 In this action all of the sulphur had been incorporated with the lime, 

 since the residue when dried would not ignite. Added a sufficient 

 quantity of water to the above solution aud sprayed an apple tree with 

 it at 10:30 a. m. March 18, sun shining, light breeze. 



About 14 hours after makiug the above experiment it began to rain 

 very gently and this was continued for 24 hours. April 23, I found a 

 great many living San Jose scales on this tree. At the time of making 

 the above test I also sprayed some of the solution on a branch of a 

 peach tree in full blossom, but this did not appear to produce any in- 

 jurious effect upon the blossom, since at the time of my visit on the 

 23d of April this branch bore as many peaches as did any of those 1 

 had not sprayed. It seems almost certain that the rain, coming on so 

 soon after the wash was applied, rendered neutral the effect of the 

 above solution on the scale insects sprayed with it. I have seen 

 orange trees that had been sprayed with the resin wash on a certain 

 day and a rain occurred during the night following the application ; 

 but the wash did not prove fatal to nearly as large a percentage of the 

 red scales as would have been the case had no rain occurred. 



On the same day that the above test was made (March 18), I also 

 tried the above mentioned lime and sulphur solution at half strength, 

 but it did not produce any apparent effect upon the San Jose scales 

 infesting the tree sprayed with it. It was now too late in the season 

 to make additional tests of this solution, but I hope to be able to fol- 

 low up this subject during the coming winter. 



From the above experiments it would appear that neither lime, salt, 

 nor sulphur when used separately are effectual in destroying the San 

 Jose scale ; and the same is true in regard to any two of them when 

 used in combination, except, perhaps, the lime and sulphur, which have 

 not as yet been sufficiently tested. It is very probable, however, that 

 these two ingredients give to the wash its insecticidal property, while 

 the addition of the slaked lime and salt simply impart stability to the 

 wash, rendering it less liable to be washed off the trees by the winter 

 rains. Should this surmise prove correct, then the directions given at 

 the head of this article for preparing this wash should be changed, an 

 equal number of pounds of lime being required with the 33 pounds of 

 sulphur, instead of only 21 pounds of lime, as at present used. 



I experienced considerable difficulty in preparing and applying this 

 wash, owing to the fact that some of the materials used are not solu- 

 ble in water, necessitating an almost constant stirring of the solution 

 while it is being sprayed upon the trees. On this account it is quite im- 

 possible to spray it uniformly upon all of the trees, aud this difficulty 

 has also been experienced by each of our fruit-growers who have used it 

 and with whom l have conversed upon the subject, or who have written 

 25910— Bull. 23 3 



