220 GARDEN FARMING 



effects are more readily seen. Instances are known where Moore's 

 Concord was evidently crossed with Black Mexican corn growing 

 nearly two miles away ; but in another case, where the Black 

 Mexican and the Moore's Concord varieties were planted side by 

 side on the same day, there was no indication of mixture beyond 

 the sixth row from the dividing line. 



" Difference in season of maturity is not always a protection 

 against crossing. The writer knows of a case in which there was 

 clear evidence of mixture in both directions between Extra Early 

 Red Cory and Stowell's Evergreen corn growing side by side, 

 although the Cory was planted some days before the Evergreen ; 

 but in another instance there was no sign of mixture between the 

 Cory and the Black Mexican varieties planted side by side on the 

 same day, all of the silk and the tassels of the Cory being ripe and 

 dry before even the earliest tassel appeared on the Black Mexican, 

 and in this case there were no late-blooming suckers on the Cory 

 to furnish pollen for the earliest Black Mexican plants. 1 



" Experience shows that neither a distance less than several 

 miles nor any varietal difference can be relied upon as a certain 

 protection against a mixture of pollen. In most farming regions it 

 is impracticable to locate a field of seed corn so as to guarantee that 

 there shall be no mixture through pollen, though much can be done 

 to lessen the probability of a mixture. How this may be best ac- 

 complished is a different problem in each case. Usually the most 

 practical way is to plant each lot of seed as far as possible from 

 any other corn, and also to have as much difference as possible in 

 the dates of ripening of the seed corn and of the corn in the 

 nearest field. 



" Fortunately, the effect of crossing in corn is rarely masked for 

 a number of generations, as it often is in leguminous plants. It 

 frequently shows so plainly in the grain which is the immediate 

 result of the cross that much of the hybrid corn can be removed by 

 careful sorting before shelling, and it is well to throw out the whole 

 ear rather than to pick out the mixed grain, as is the common prac- 

 tice, because crossing does not always change the appearance of 

 the grain the first season, and there is a strong probability that on 



1 Adapted from Bureau of Plant Industry, Bulletin No. 184, " The Production of 

 Vegetable Seeds," by W. W. Tracy, Sr. 



