258 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 condi- 

 tion 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 com- 

 mon insect poison materials. They may be used in combi- 

 nation with lime-sulfur and also with Bordeaux mixture. 

 (See spray formulas in the Appendix.) 



REVIEW. 



1. 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: 648, Root Knot; 938, Bitter- 

 rot; 618, 1053, Leaf-spot; 1056, Pear enemies; 1213, 930, Smut; 1041, 

 Eelworm; 1058, Rust; 1224, Wheat scab; 1226, Take-all of Wheat; 856 

 925, Garden diseases. Ark. Sta. Bui. 28, Fumigation. 



