OX CORN BREEDING 141 



of general inferiority should be detasseled as a whole, since 

 in such cases it is manifest that the whole family has an 

 hereditary tendency to become imperfect. 



The main point, however, in the selection before tassel- 

 ing is the occurrence of barren stalks. Barren stalks are 

 plants which do not produce a fertile ear. As a rule they 

 have imperfect ears and more or less developed tassels. It 

 is generally surmised that this barrenness is hereditary, 

 although to a large degree it is dependent on climatic con- 

 ditions. As a matter of fact, seed-corn which has been 

 fertilized by pollen produced from barren stalks is liable to 

 give rise to an increased number of useless plants. In many 

 cases the number of barren stalks reached as high as thirty 

 per cent, and it is evident from this that they are one of the 

 greatest sources of loss in corn growing. They are even 

 worse than a simple loss of that amount, since, except for 

 detasseling, they deteriorate the quality of the neighboring 

 ears as seed corn by their pollen. But a little care in select- 

 ing will materially lessen this enormous loss. The method 

 of breeding the seeds of single ears in rows has proved that 

 different degrees of barrenness are inherent in different fam- 

 ilies. Some ears produce more than twelve times as many 

 barren stalks as others, and for broken stalks a similar rule 

 of family individuality prevails. Hence it is clear that rows 

 which are marked in this deficiency should be detasseled 

 as a .whole, and that their ears should be excluded from the 

 ultimate selection. Only strains with the smallest possible 

 propensity to barrenness are worth cultivation. By follow- 

 ing these rules the per cent of barren stalks has been greatly 

 reduced. For instance, in Illinois, on farms where this num- 

 ber reached as high as about sixty per cent, it has been re- 

 duced by selection, in the lapse of five years, to about ten or 

 fifteen per cent. 



The high importance of the combating of this evil may 



