DEVELOPING | 
PRODUCING A FouR: WAY CROSS — 
Hybrids Pure INBRED STRAINS 
Many combination crosses of in- 
breds are made each year... 
single-cross .. . three-way cross 
. . . and double cross. 
Out of the many different crosses 
tried . . . afew are usually found 
to be superior to those already pro- 
duced. 
Those showing the most outstand- : 
ing characteristics are selected | WIAIIVE EARS 
for further testing. 

CONVERGENT IMPROVEMENT... since 1932 
Since 1932 ... in addition to the regular methods of inbreeding ... 
Pioneer has been improving many of the original inbreds by ‘‘back-cross- 
ing.’ This method is sometimes known as .. . convergent improvement. 


TEST PLOTS 
Over 3,500 crosses are tested 
each year... in replicated, hand 
planted performance test plots. 
POPULARITY TEST PLOT LOCATIONS 
Pioneer experimental hybrids are 
tested ...in the farmers’ fields 
... in hundreds of popularity test 
plots . . . usually two or more plots 
in each county. 
HAND PLANTING 

