DIPPING AND FUMIGATION OF NURSERY STOCK 



21 



phide as with the hydrocyanic-acid gas and, as shown by the following 

 table, the same number of trees were used. The first dry and the first, wet 

 set of trees were treated for an hour with carbon bisulphide at the rate of 

 1 pound of the insecticide to 100 cubic feet of space. Sets No. 3 and 4 were 

 treated for an hour also, but the carbon bisulphide was used at the rate of 

 iy 2 pounds to the 100 cubic feet. 



In treating the trees, each set was placed in the fumigating box -sep- 

 arately, as with the hydrocyanic-acid gas. Near the top of the box a shelf 

 was constructed upon which a shallow pan was placed. The nursery stock 

 was placed in the box, the required amount of carbon bisulphide poured 

 into the pan and the lid closed. 



Eighty apple trees heavily infested with San Jose scale were treated 

 with carbon bisulphide as is shown by the following table. 



TABLE 9. APPLES TREATED IN 1916 



As is shown, counts made May 14 and 25 definitely show that carbon 

 bisulphide used at a strength of either 1 to 100 or 1% to 100 will not control 

 scale. As compared with the check,, however, it is evident that a number of 

 the insects were killed but not enough to warrant its use. 



On April 9, 1917, the following trees were treated with carbon bisul- 

 phide, 11/2 to 100. 



TABLE 10. APPLES TREATED IN 1917 



The results obtained in 1917 are practically the same as those obtained 

 in 1916 and they also show that carbon bisulphide used at the rate of l l / 2 to 

 100 will not control San Jose scale. 



