24 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 177 



Object. The object in using lime-sulphur was to determine definitely, 

 if possible, its exact efficiency for killing scale on nursery stock and its in- 

 jurious effects, if any, upon the plants. L/ime-sulphur is the cheapest ma- 

 terial used in the control of San Jose scale and as no fumes are produced, 

 it is less dangerous to use than hydrocyanic-acid gas or carbon bisulphide. 



Procedure. First a water tight wooden V-shaped trough was made, 9 

 feet long and 8 inches deep. This trough held with ease 8 gallons of the 

 solution. The number of trees to be dipped were divided into four sets. 



In the first set the tops and trunk, down to the roots only, were dipped 

 and those trees dipped in 1916 and 1920 were immersed and immediately 

 removed, while those dipped in 1917 were left immersed for five minutes. 

 With the second set of trees the tops and roots both were dipped. With the 

 first two sets lime-sulphur was used at the rate of 1 gallon to 9 gallons of 

 water. The third and fourth sets were treated exactly as the first two 

 except the lime sulphur was used at the rate of 1 gallon' to 7 gallons of 

 water. 



After the trees had been dipped they were allowed to drain for a few 

 minutes, then set out. 



Effect of lime-sulphur upon San Jose scale. As shown by the following 

 table, forty apple trees, heavily infested with San Jose scale, were dipped 

 in the lime-sulphur solution. 



TABLE 13. APPLES TREATED IN 1916 



*Both tops and roots dipped. 



These results show that lime-sulphur will, to a very large extent, con- 

 trol San Jose scale on nursery stock but that the control may not be com- 

 plete. Every tree was thoroly dipped, care being taken that every branch 

 and twig was completely wet to the top, and the writer is convinced that 

 none of the insects escaped immersion. Also a count of the scale was made 

 from every tree and as shown by the results a very small percentage was 

 alive a month after treatment. So far as the strength of the solution is 

 concerned, the weaker gave the best results; however, there is very little 

 difference in the strength of the two solutions used and the fact that the 

 weaker solution gave the better results if of little significance. 



