200 SPRAYING MATERIALS 



pump, and pump the liquid back into itself until a creamy 

 white mixture is produced. This is a "stock solution," and 

 ought to keep for weeks or even months without the oil separating 

 out. It is diluted for use according to the insect to be attacked. 

 With aphids, which have very soft bodies, one part of the stock 

 solution to ten or even fifteen parts of water may be strong 

 enough. For those insects which are more difficult to kill, such 

 as the San Jose scale, it may require one part to four or five 

 of water. 



Tobacco Extracts. There are a number of tobacco extracts 

 on the market which are very satisfactory for sucking insects, 

 especially for the aphids. In the Northwest it is customary 

 in many sections, where the aphis is plentiful, to include some 

 form of tobacco extract with the regular sprayings for fungous 

 pests and chewing insects so that the spray kills sucking and 

 chewing insects and fungous diseases at one operation. 



QUESTIONS 



1. Discuss the importance to the orchardist of a knowledge of spray 



materials. 



2. Under what conditions is it best for the orchardist to prepare his own 



spray mixtures? 



3. What are some of the objections to the use of Bordeaux mixture? 



4. Describe the preparation of stock solutions for Bordeaux. What is 



the advantage of these solutions? 



5. Describe the making of Bordeaux mixture from these stock solutions. 



6. What is commercial lime-sulfur? How is it used? 



7. Describe the home-made lime-sulfur concentrate. 



8. Tell how to make self-boiled lime-sulfur. 



9. Give the advantages of arsenate of lead as an insecticide. 



10. Give directions for the use of Paris' green. 



11. What are miscible oils? 



12. Why are oils especially valuable in killing scale insects? 



13. Give the formula for kerosene emulsion and describe the methods of 



preparing and using it. 



