SAN JOS:fi SCALE INVESTIGATIONS. II* 



V. H. LowB. 



SUMMARY. 



In a series of winter spraying experiments with refined (150° 

 fire test) kerosene oil, peach trees were killed with one applica- 

 tion of a 20 per ct. mixture of oil with water, and plums seri- 

 ously injured with a 40 per ct. mixture. Pears and apples 

 were not injured except by the pure oil, and then only slightly. 

 The 20 per ct. mixture of kerosene had no apparent effect on 

 the scales, but the 40 per ct. proved effectual in every case. 



Summer applications of 100° and 150° fire test oil showed the 

 former to be dangerous, burning the leaves at a percentage too 

 low to kill the scale, while the latter did not injure the foliage 

 except when applied undiluted. 



I. SPRAYING- EXPERIMENTS WITH KEROSENE OIL. 



The experiments herein recorded were begun two years ago, 

 the original intention being to duplicate them the following year. 

 At that time kerosene oil was used more extensively in combat- 

 ing the San Jos6 scale than now. Although crude petroleum is 

 taking its place in many localities it is still used extensively in 

 this State. Where but few trees are to be treated it is often 

 more convenient to use it than crude petroleum, as it is more 

 easily ohtained, and in most localities costs less in small 

 quantities. 



The number of trees and bushes treated, 382, is not a large one 

 for a series of experiments of this kind, but is sufficient to give 



♦Reprint of Bulletin No. 194. 



