102 FIELD CROPS 



might be added, which would make a five-year rotation with 

 one year of corn, one year of clover, and three years of grain. 

 Unless considerable quantities of fertilizer were applied, such 

 a rotation would by no means maintain the productivity of 

 the soil. Another practical five-year rotation including 

 corn is: First year, grain; second year, meadow; third year, 

 pasture; fourth year, corn; fifth year, grain. 



In the Southern states, corn ranks second only to cotton 

 in importance. These two crops are almost always included 

 in any rotation which is devised for this section. Cowpeas 

 are quite generally grown to add nitrogen and are sometimes 

 plowed under to increase the vegetable matter in the soil. 

 They are often planted with the corn, either in the rows or 

 between them at the last cultivation. A very good rotation 

 for the South is: First year, corn and cowpeas; second 

 year, cotton followed by winter grain; third year, grain, 

 followed by cowpeas for hay. 



(See also Chapter XXVII for other rotations.) 



DISEASES OF CORN 



121. Smut. Corn smut is well known to everyone 

 familiar with corn; in some years, when conditions are 

 favorable, considerable damage is done by it. It appears 

 as black, slimy masses, which may be on the stalks, leaves, 

 tassels, or ears. Corn smut is a parasitic plant which lives 

 on the juices of the corn plant, and in this way reduces the 

 total valuable product of the crop. The smut masses which 

 appear on the surface are made up of myriads of spores 

 by which the disease is reproduced. These spores are 

 capable of living over winter in the soil or in manure piles. 

 They may even multiply in the manure under favorable 

 conditions and then be spread on the soil with it. When 

 they start to grow in the spring, the smut plants they pro- 



