No. 6. DEPARTMENT OF AGRICULTURE. 369 



Many experiments sliow that when the tubers of any hill are used 

 as seed each has a strong tendency to resemble the parent hill in all 

 its qualities. Every potato grower is consciously or unconsciously 

 changing his varieties, either for better or worse. A number of 

 methods of choosing seed potatoes are in use. Having never seen 

 any comparison of the merits and defects of more than two or three 

 together I will try to present a fair discussion of the whole subject. 



THE USE OF SMALL SEED 



By carefully digging a field of potatoes it will be seen that a 

 few of the poorest hills produce a larger proportion of the small 

 tubers. The best hills produce mainly large ones. Diseased hills 

 are almost certain to have a light jdeld and the tubers mainly small. 

 I have selected hills for seed for 11 years, always choosing the best 

 yielding. Now I get less than 2% or small in good seasons, even 

 though the hills are planted- only a foot apart to produce the medium 

 sized stock demanded by city markets. I do not feel that the reduc- 

 tion of the small tubers till there not enough to plant the next year's 

 crop is a serious objection. Farmers use small seed because it is 

 cheap. While it is possible that the increased yield from the use of 

 large seed might not pay the extra cost, the use of small seed year 

 after year increases the proportion of weak and diseased hill, the 

 yield diminishes, and the variety is said to be "run out." Many 

 scientific experiments have almost always shown better yields from 

 large than small seed when sorted in the usual way. The Geneva 

 Station has made a test in which care was taken to have the large 

 and small tubers taken from the same hills in order that the inherited 

 vigor might be equal. Under these conditions the small seed was at 

 least as good as large pieces of equal weight. While an exceptionally 

 all the best hills in a field of tubers longer than the usual variety of 

 bad season might produce many weakened hills with small tubers 

 small seed may be considered safe if taken from a stock from which 

 the weak hills are kept eliminated by some method of seed selection. 



THE USE OF LARGE SEED 



This produces a better crop and better seed at an increased cost. 

 Often farmers buy new varieties which produce well at first because 

 the seedsmen have grown them using large seed and have had good 

 winter storage conditions. The yield often falls down as soon as 

 handled under the usual farm conditions. 



SELECTING SEED ACCORDING TO AN IDEAL TYPE FOR EACH VARIETY 



This plan would be of immense value if we were certain just what 

 points in the appearance of a tuber were reliable indications of its 

 value as seed. The Uncle Sam variety varies all the way from smooth 

 flat-oval shape to a longer and rougher type, the vine, flower, etc. 

 being the same. I once selected the hills which were smooth, dis- 

 carding those longer and rougher. The yield compared to other 

 varieties declined so rapidly that it was apparent that the poor look- 

 ing hills were the ones that had given the yield. With the Rural 

 this same smooth type is found in the best hills and is the best seed. 

 Tubers longer and narrower than the usual type of any variety ar^ 



