72 THE SAN JOSE OE CHINESE SCALE. 



MEANS OF CONTROLLING THE SAN JOSE SCALE. 

 INSECTICIDE APPLICATIONS. 



Active experimentation with different remedies for the San Jose 

 scale was instituted b}" this Office promptly after the discover}- of the 

 occurrence of this pest in eastern orchards and nurseries. A full 

 record of these earl}^ experiments is given in Bulletin No. 3 (new 

 series) of this Bureau, pages 56 to 71. The subject of these experi- 

 ments will not be gone into in detail. Thev covered the use of the 

 lime-sulfur washes emploj^ed against the San Jose scale in California, 

 the hj^drocyanic-acid-gas treatment for orchards and nursery stock, 

 lye washes, pure kerosene, kerosene-soap emulsions, resin Avashes, and 

 soap washes. The early experience with the lime, sulfur, and salt 

 wash was unfavorable, largelv due apparently to the fact that the 

 observations on the trees treated were not continued long enough to 

 note the effect of the late summer results. Good results were 

 obtained with the kerosene emulsions, and particularly with the soap 

 washes, and the fish-oil-soap wash became one of the standard means 

 of controlling the scale and is still among the best and safest washes 

 to be used, altho rather more expensive than necessary, except where 

 only a few trees are to be treated. 



The subject of remedies was promptly taken up by different experi- 

 ment station entomologists in the East, and a vast body of experimen- 

 tal data is now on record in various station publications. The stud}' 

 of the subject of remedies has also been continued by this Bureau and 

 reported in different bulletins. The lime, sulfur, and salt wash at 

 first reported on adversely by us was afterwards deoionstrated to be 

 of real value, and experimental work was taken up. first by the Illinois 

 Experiment Station, under Professor Forbes, and subsequently by other 

 stations, and it has now come to be the general!}^ accepted remed}^ for 

 the San Jose scale. Without going at all in detail into the subject 

 historicalh', it is sufficient for the purpose of this bulletin to reproduce 

 the recommendations for the control of the San Jose scale substantially 

 as o'iven in the fourth revised edition of our Circular ttS. 



In addition to the standard remedies mentioned below a great many 

 proprietary substances have appeared, and some of these have some 

 merit. The best of these are certain merchantable brands of lime- 

 sulfur compounds, and oils which have been treated by some secret 

 process to render them miscible in water. The predominating con- 

 stituent of the latter is mineral oil, and the resulting mixture, which 

 is not apparentl}' an emulsion, is undoubtedly of value if used in suf- 

 ficient strength to get the required amount of oil on the trees. There 

 is no advantage in using an}' of these compounds over the standard 

 insecticides, and their greater cost is a distinct objection, together 



