MAKING 
AND TESTING 
MENTAL HYBRID CROSSES— THE SECOND STEP 
P lOiNKEK BREEDERS niakc alioiii 3,’)(),()()0 liaixl-poUinalions everv vear. 
W hen corn l)ree(lers cross two pure inlireds. ea«'li hearin;; different 
characteristics, the off-spring, a “two-way” or “single cross” inherits tlie best 
characteristics of its parents, and always grows stronger and more vigorous 
llian either of tliein. 
Out of thousands of “single crosses” produced every year, otdy a few 
are good enough to use lor experimental work on final “four-way crosses.” 
Tlie “four-way” hybrid cross is develoiied by crossing a pair of “two-way” 
or “single crosses,” each ol which jjossesses unlike characteristics. 
Of tlie hundreds of final crosses made year after year by PIONEER corn 
breeders, only a small nuniher prove su|)erior to the present commercial 
hybrids. 
These few outstanding combinations are then tested, over a number of 
years, for yield, lodging, and maturity, in localities where they are to he sold. 
POLLEN BAGS ON TASSELS; GLASSINE BAGS OVER EARSHOOTS 
CROSSING TWO INBREDS TO PRODUCE A “SINGLE CROSS" 
BREEDERS CROSSING TWO "SINGLE CROSS” HYBRIDS 
THE TWO INBREDS ON EITHER SIDE WERE CROSSED TO PRODUCE 
HYBRID IN THE CENTER 
Locations showing large yield test plots where 
PIONEER hybrid crosses were tested in 
Iowa, Minnesota, and .South Dakota, last year. 
