236 PRODUCTIVE FARMING 



An insecticide is to be used for insects, and a fungicide 

 used for the plant diseases. These may be combined into 

 one spray material. 



Weaker sprays are necessary on plants when the leaves 

 are on; stronger sprays when the trees are dormant. 



Lime-sulfur is used both as a winter spray and as a sum- 

 mer spray, but the strength must be made to suit the con- 

 dition of the trees or other plants. It is a fungicide and also 

 a special insecticide for the control of scale insects. 



Soluble oils are for winter use only and are especially 

 for scale insects. 



Bordeaux mixture alone is a fungicide and, in different 

 strengths, may be used either when the trees are dormant or 

 when in leaf. 



Paris green and arsenate of lead are two of the most 

 common insect poison materials. They may be used in com- 

 bination with lime-sulfur and also with Bordeaux mixture. 

 (See spray formulas in the Appendix.) 



REVIEW. 



l.-What are the three main causes of plant diseases ? 



2. Name two fungous diseases of the apple. 



3. Name five diseases of the peach. 



4. Describe peach yellows and tell of the best remedy. 



5. Tell how to prevent apple scab. 



6. Tell of the relation of cedar apples to the rust disease of apples. 



7. Give four causes of potato scab and the remedy for each. 



8. Describe the treatment of seed potatoes to prevent the planting 

 of scab disease. 



9. Describe the treatment of oats to prevent smut disease. 



10. Give the objects for each of the three spring sprayings of apple 

 trees. 



11. Give the material to use at each time. 



12. Give all the principles of spraying that you can. 



References. — U. S. Farmers' Bulletins: 219, Lessons from the 

 Grain Rust Epidemic of 1904; 221, Fungous Diseases of the Cranberry; 

 243, Fungicides and Their Use in Preventing Diseases of Fruits; 250, 

 The Prevention of Stinking Smut of Wheat and Loose Smut of Oats; 

 283, Spraying for Apple Diseases and the Codling-Moth in the Ozarks; 

 345, Some Common Disinfectants; 435, P. 28, Lime-Sulfur. 



