200 SPRAYING MATERIALS 



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. 



Tohacco 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 orcliardist 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. 



