THE CONTROL OF INJURIOUS INSECTS 



387 



tion 10 days or 2 weeks after the 

 blossoms fall should be diluted to a 

 sp. gr. of 1.005 o^ account of the 

 tenderness of the apple pedicels. 



The amount of spray liquid 

 varies with the size of the tree. A 

 thrifty 9- or lo-year-old tree on 

 the average requires i3^^ gal. for the 

 dormant spray and i gal. for each of 

 the later sprays. A 30-year-old tree 

 requires 5 gal. for the dormant spray 

 and 4 gal. for each of the later 

 sprays. 



In boiling lime and sulphur to- 

 gether according to the formulae 

 given above, two sulphides of cal- 

 cium (CaS4 and CaSa) and the thio- 

 sulphate of calcium (CaS203) are 

 formed. These are soluble in water. 

 If too much lime is used a sediment 

 will form. Only the best stone lime 

 should be employed, and the boiling 

 should not be too prolonged as in- 

 soluble compounds are formed. 



3Ca(OH)2+ iiS = CaS4 + 



CaSs +CaS203 + 3H2O. 



When the hydrometer has the 

 Baume graduation marks ranging 

 from o to 36° the mixture for^the 

 San Jose scale (dormant stage) 

 should test between 4.5° and 5° 

 Baume, and for the summer spray- 

 ing about 1° Baume (Fig. 250^. 



The following table of dilutions 

 of lime-sulphur has been calculated 

 for both hydrometer graduations: 



Concentrated 



I 2 



Fig. 250. — Diagram of hydrometer 

 in use. i, For concentrated solutions 

 and graduated from 1.21 to 1.32 

 specific gravity, with surface of liquid 

 indicated at a-b; 2, for diluted solu- 

 tion and graduated from i.oo to i.io 

 specific gravity, with surface of liquid 

 indicated at c-d. (After Corby.) 



