762 NEW YORK STATE MUSEUM 



better condition than it was two years ago. It is only necessary 

 to compare pi. 5, 6 to obtain a relative idea of the value of 

 spraying for San Jose' scale. The experimental orchard was 

 the first in that vicinity to become infested with the San Jos6 

 scale; and two years ago it was composed of a very bad-looking 

 lot of young trees. Today the conditions are reversed, so far 

 as these two orchards are concerned, and the later infested, 

 near by orchard is in much worse shape than the other. It i& 

 true, that the former is composed of appletrees set a consider- 

 able distance apart, and that naturally makes the orchard look 

 thin compared with the more closely set peachtrees and pear- 

 trees, but a close examination shows that the true relative con- 

 dition of the trees is very fairly expressed in the two plates. 



The poor results obtained from early spring applications of 

 kerosene and mechanical emulsions of the same in 1900, led 

 to the concentrating of the work on the more promising insecti- 

 cides, namely, crude petroleum and whale oil soap in various 

 combinations. Two crude petroleums were used, care being 

 taken to make field tests of the oil just before spraying, conse- 

 quently there can be no doubt regarding its weight as deter- 

 mined by the hydrometer. One of the crude petroleums used 

 was obtained from a local oil dealer handling the products of 

 the Standard oil co. This is a quite fluid, greenish oil, and it 

 gave a field reading of 41.8° Beaume. It was presumably about 

 the same as that used last year, as it appeared no different and 

 was obtained from the same source. The other crude petroleum 

 was received directly from the Frank oil co., Titusville Pa. 

 This was of a light amber color, and it was said to test from 

 44° to 45° on the Beaume oil scale. In the field it gave a read- 

 ing of 43.3° Beaume'. Both of these tests were made at a tem- 

 perature of about 65° F. These two crude petroleums, for the 

 sake of brevity, have been characterized in our records as 

 Standard oil and Titusville oil respectively, and these names 

 will be used in the following pages. Comparative tests of 

 mechanical emulsions of both these oils were made, and the 

 results are given below. The spraying was done April 11, which 

 was bright, with at times a rather strong wind. 



