84 PRINCIPLES OF FARM PRACTICE 



corn-leaf, beetles, and corn-ear worms may at times prove 

 destructive. Space will not permit a detailed discussion of 

 them. Consult Chapter XVII which is a general account of 

 insects as related to agriculture. 



Diseases of corn. Corn is not subject to many diseases. 

 Its most common disease is corn smut, for which no direct 

 remedy of practical value has yet been found. Fortunately, 

 comparatively few plants in a field are infected with smut. 

 The spores of corn smut remain in the ground over winter, 

 germinate in the spring and develop chains of new spores. 

 These new spores, being blown about by the wind, may 

 infect any part of the corn plant with which they come into 

 contact. There are two ways suggested for reducing the 

 damage to corn by smut: first, to destroy the smut balls 

 before they open to scatter spores; second, to rotate corn 

 with other crops. Furthermore, seed selected from vigorous 

 plants situated in areas free from smut will likely produce 

 plants resistant to this disease. 



Another disease now being carefully investigated is corn- 

 root rot. It is important not only because of its injury in 

 infected fields to corn plants, but because the same organism 

 that produces corn-root rot also causes a disease of wheat 

 and some other cereals, known as wheat scab. A discussion 

 of plant diseases and their control will be found in Chapter XV. 



How to get seed corn ready for the next year. At- 

 tention has been called to the fact that seed corn selected 

 from the crib is likely to prove unsatisfactory, especially in 

 its low percentage of germination. The selection of seed 

 corn is an important matter. It should begin in the field 

 before the corn is harvested. The following is one method 

 of seed selection: Search the field for the best plants, taking 

 into consideration the entire plant, including the ear, and 



