32 



BULLETIN 195; U. S. DEPARTMENT OF AGKICULTUEE. 



from selection work is the weeding out of these undesirable strains. 

 It is not at all unlikely that from 5 to 10 per cent of weak, diseased, 

 or unproductive plants may be found in all unselectcd seed potatoes. 

 It is also equally certain that in nine cases out of ten in ordinary field 





Ai^erage 



Bb/s of pr/mes per ^cre - 22. 66 

 ■■ Ci///s ■ ■ -24.86 



Bb/s of primes per /4cre — /O. /2 

 ■ CU//S • - -23.76 



Bti/s of primes per Acre — 23./6 

 ■■ ca//s ~ ■■ -39.3S 



BbJs of pr/mes per /icre — 20.90 

 ■ ■■ ca//s ■■ ■■ ~2030 



Bi>/3 of primes per /Icre — " O.OO 

 ■ ca//s - ■■ - 22:20 



Bb/s of pr/mes per /Sere — S5.53 

 CI///S - ■■ — 30S3 



Bb/s of pr/mes per /Icre — 73.S6 

 ■■ CC///S ■■ - — 36.32 



Bb/s of primes per ficre — /7.33 

 • CC///S ■■ ,« - ~ 49.SO 



Bb/s of pr/mes per Acre 



CU//S 



33.32 

 29.-4a 



Bb/s of pr/mes per /Icre ~ 60.06 

 - ■ C(///s _■■ ' — 35.6-4- 



0b/s ofpn.nes per /Icre ■ — 3-4 /2 

 - ■• Cij//s • ■ -33.64 



Bb/s of primes per /Icre — //3.SO 

 ■■ ■■ CO//S ■■ ■ — 36.7^ 



BA/s of primes per/lcre — 33.38 

 ■■ - CU//S - ■ - 47.96 



Bb/s of pr/mes per /Icre — 67.93 

 Cfj//s ' - — 28.6/ 



Bb/s of pr/mes per Acre ^ 80.74- 

 ■ CU//S -• ■ —30.S3 



Bb/s ofpr//7>es per Acre 

 ■ cv/Zs 



6578 

 2^.42 



Primes 



I Cul/s 



Fig. 2. — Diagram showing the hill-selection performauce record, season of 1912. 



practice these are unrecognized, because the weak or diseased plants 

 are scattered here and there throughout the field and are obscured 

 by surrounding healthy plants. Their resultant effect on yield is 

 also unnoted and will probably remain so until we demand a practi- 

 cally perfect stand. 



