48 Journal of the Department of Agriculture. — July, 1922. 



time for January and February planting. Some growers are fairly 

 successful by bagging their seed, and placing it in a warm moist 

 situation, often lightly covering it with stable manure which will 

 raise the temperature and cause the tubers to sprout. Care, how- 

 ever, should be exercised not to raise the temperature too high as the 

 tubers are likely to decay. Potatoes grown in the low veld and lifted 

 in October could be profitably used by the farmers for January and 

 I'ebruary planting. 



Improvement of the Crop. 



It is the experience of many growers that potatoes degenerate if 

 planted in the same locality, especially in a warm climate, for a 

 numlaer of years. The chief causes of this degeneracy or decreased 

 productivity appear to be : — 



1. Failure to select the right seed. Most farmers select their 

 seed at the heap with the result that small tubers from low-yielding 

 stools or hills are mostly selected. As like has a tendency to beget 

 like, these small tubers will generally be responsible for low yields 

 in the succeeding crop. This goes on from year to year, until the 

 farmers find that their variety has " run out " or deteriorated. To 

 remedy this, hill selection is recommended. The grower should 

 select his seed in the field from the hills that yield most. If this is 

 done for a number of years — always selecting the best from among 

 the best — a highly productive strain which is not likely to degenerate 

 could be developed. 



Where experiments have been conducted with the progeny from 

 high and low yielding strains it has been unmistakably proved that 

 this character of the potato plant breeds true, hence the necessity of 

 using tubers from productive hills. 



2. Some investigators attribute degeneracy in potatoes largely 

 to diseases carried in the tuber. The organisms causing the diseases 

 have as yet not been isolated. Typical diseases of this character are: 

 spindling sprouts, curly leaf, and mosaic disease. 



As remarked above this so-called degeneracy can largely be 

 counteracted by hill selection and by the use of sound, well grown 

 tubers. There is always the tendency for the potato to revert back 

 to its ancestors or to become " wild," and for this reason seed selec- 

 tion should be rigidly carried out and continued from year to year. 



In selecting seed in the field it is well that the grower should 

 keep the following points in mind and breed for same : — 



1. High yield, ascertained by weighing, measuring, or count- 



ing the progeny from each hill. 



2. Disease resistance; some plants easily succumb to diseases 



while others resist them. 

 8. Good keeping qualities; some potatoes keep well for a long 

 time while others cannot be stored or kept for too long 

 a period. 



4. Good colour of flesh and skin ; this depends on public fancy- 



5. Skin of a desirable texture. 



6. Tubers of good shape. 



7. Shallow eyes and few in number. 



8. Upright vigorous plants, showing constitution. 



9. Trueness to type which varies with the variety. 

 10. Maturity. 



