52 ELEMENTS OF FARM PRACTICE 



Diseases and Insects. — The diseases to which wheat is 

 most subject are scab, rust, and smut. Scab attacks the 

 glumes, or chaff, and causes shrunken kernels. It is shown 

 by pinkish spots. Rust weakens the straw and causes 

 shrunken kernels. There is leaf rust and stem rust, the 

 latter being the more destructive. The spores of this dis- 

 ease live over winter on some other plant, as the common 

 barberry. Smut is either loose or stinking. The former 

 attacks and destroys the glume and kernel; the latter pro- 

 duces a smut ball instead of a kernel. For treatment for 

 smut see page 157. 



The insects which damage wheat are 

 chiefly the Hessian fly, chinch bugs, grass- 

 hopper, and army worms. The fly lays 

 eggs in the stem, weakening and breaking 

 it. The chinch bug sucks the sap. Grass- 

 hoppers and army worms devour the 

 plants. 



Great losses are caused by these diseases 

 and insects. For methods of prevention 

 see reference books and bulletins. 



'^ Questions: 



Figure 18c. - 1. When would wheat be dearer, generally 



Chinch bug. enlarged speaking, when it is being imported or exported? 

 Why? 



2. Can you determine whether, all thin^ being considered, it 

 is more profitable to raise wheat at high prices? 



3. Why does wheat do better after a cultivated crop? 



4. How many uses of wheat can you enumerate? 



5. What is the best way to combat wheat insects? 



Arithmetic: 



1. What is the value of an acre of wheat yielding 13.5 bushels 

 at 85c. a bushel? Of an acre yielding 24 bushels at $2.25 a bushel? 



2. If it costs $11.15 an acre to produce wheat, how much does 

 it cost per bushel, if the yield is 15 bushels? If 20? If 25? 



3. Three spring-wheat states averaged 182,000,000 bushels a 

 year. It was estimated that smut caused 10% of damage, If there 

 had been no smut, how many more bushels would there have been? 

 If wheat was worth $1.17 a bushel, how much was lost from smut? 



4. If the United States Exports 84,000,000 bushels of wheat annu- 

 ally, how many persons would this amount supply, if each one consum- 

 es 4.7 bushels a year? How many times the population of Chicago? 



