448 



CORN 



A smut spare may alight and develop on the ear. Instead of the 

 plant food being used for the kernels, the mycelium of the smut 

 withdraws it for use in the formation of the smutted mass. 



Unfavorable Soil and Climatic Conditions. In light soils not suit- 

 able for corn production, a large percentage of barren stalks are pro- 

 duced. The plants in general, under such conditions show a lack of 

 strength. Should this unsuitable condition be accompanied by un- 

 favorable climatic conditions, such as an especially wet spring with 

 cool days and nights so unfavorable for the growth of the young corn 

 plants, the amount of barrenness will be increased. 



Too Thick Planting. When corn is planted so thick that the 

 soil is unable to supply enough plant food to maintain the stalks 

 and at the same time produce ears, a large number of barren stalks 

 result. From a given area of land, the largest yield of corn will be 

 secured if the amount of seed planted is just within the limit of the 

 ability of the soil to support the resulting plants. Beyond this limit, 

 the ear is sacrificed and the stalks become smaller. 



The following table will show the gradual tendency toward an 

 increasing amount of barrenness as the number of kernels (or stalks) 

 per hill increases. 



This is the result of 39 experiments in 12 counties in Iowa, cover- 

 ing in some a period of 3 years (1905, 1906 and 1907) — years of 

 quite varying climatic conditions. 



EFFECT OF THICKNESS OF PLANTING ON PER CENT BARREN STALKS. 



Kernels or stalks per hill. 

 Per cent barren stalks . . . 



1.0 

 3.2 



1.5 

 3.4 



2.0 

 3.8 



2.5 

 4.6 



3.0 

 5.6 



3.5 

 8.1 



4.0 

 9.7 



4.5 

 11.6 



5.0 

 14.5 



Hereditary Influences. These influences are clearly brought out in 

 the great variation in the amount of barrenness noted from individual 

 ears within a given variety of corn, making it possible to materially 

 decrease the percentage of barren stalks by selection. 



The following table will illustrate the above heading. In arrang- 

 ing this data the germination test and the per cent stand, were selected 

 as nearly alike as possible. 



STORY COUNTY 1907. 



S — Strong. W — Weak. B — Bad or Dead. 



