Potato Breeding 51 



Deep eyes cause waste in peeling. They hold mois- 

 ture, thereby causing decay in storage. The tuber 

 should have enough eyes to make good seed, but not so 

 many as to make peeling difficult. 



Early varieties may mature in 70 to 90 days after 

 planting; second-earlier in 90 to 130 days; and late 

 varieties may continue to grow for 200 days. It is im- 

 portant to choose a variety adapted to the locality. 



The haulm and leaf are considered more important 

 than formerly. Large haulms require wider spacing of 

 plants and greater expense for spraying. Short-haulmed, 

 upright, heavy-leafed tops are not as susceptible to dis- 

 ease as the prostrate types. The upright types are more 

 likely to suffer during very dry spells, however, because 

 the tops do not prevent the evaporation of moisture from 

 the soil as do those of the more prone types. Care should 

 be exercised to select a variety which is well suited to 

 local conditions and which will grow vigorously. Dif- 

 ferences in vigor will be noted in different strains of the 

 same variety. 



Leaves with thick cuticles are not as easily penetrated 

 by disease spores. 



When a period of drought is followed by a wet spell, 

 second growth is likely to begin. The dry weather 

 checks growth and the tubers begin to mature. wSubse- 

 quent wet weather restarts growth. Such abnormalities 

 should be discarded in selecting seed. 



It is essential that the seed be as represented. None 

 but experts can tell the different varieties apart, so seed 

 should be obtained from a reliable source. 



The half-tone illustrations in Plates III to VII show 

 some of the desirable potato forms, and also results in 

 breeding. 



