Till RTEES Til AX X UAL MEETIXG. 83 



Fighting the San Jose Scale-Insect. The Latest and 

 most Effective Sprays. 



By Prof. JV. E. Britton. 



The ideal spray for killing this destructive insect should have 

 these requirements : 



1. Cheapness of materials, 



2. Ease of preparation. 



3. Effectiveness in killing insects. 



4. Not injurious to trees. 



Such a spray has not yet been found. Formerly, whale-oil 

 soap was used and recommended, but this was too expensive 

 and was not very easy to prepare. The oils, especially crude 

 oil, are fairly cheap, are easy to apply, and are certainly effective 

 as an insecticide, but are liable to cause injury to the trees, and 

 therefore we cannot recommend their use. Many trees in Con- 

 necticut have been sprayed with oils during the past four years 

 without apparent injury. Both kerosene and crude oil have 

 been employed, and each has been used undiluted and in 25 per 

 cent, mixture with water. On the other hand, many trees have 

 been seriously damaged by the oils in Connecticut and in other 

 States, notably Ohio. The pumps that mix oil and water can- 

 not be relied upon to give the proper percentage of oil, and at 

 times nearly clear water is being sprayed upon the tree and 

 then perhaps clear oil. These pumps may work nicely when 

 new, but after being stored for a season will not do satisfactory 

 work, even if taken apart and cleaned and the valves packed. 



The lime, sulphur and salt mixture combines cheapness of 

 materials, effectiveness, and is non-injurious to the trees — but 

 it is not as yet as easy to prepare as some other mixtures. Over 

 40,000 trees in Connecticut were sprayed with some form of 

 this mixture last season wath generally satisfactory results. In 

 our own spraying tests about 11,500 trees were treated, with 

 the result that the scale was well controlled in most cases and 

 the trees were all benefited by the treatment. I feel that we 

 must w^ork along the line of cheapening this mixture and mak- 

 ing it more easy to prepare. Our experiments during the past 

 season showed : ( i ) that the scale can be controlled by a single 



