154 The Potato 



cutting. Trouble with soil diseases affecting the stand 

 is causing the use of similar small seed in some of the 

 western potato-growing sections. The use of small culls 

 as seed is usually condemned in the United States. Very 

 often the vitality of the cull seed is low on account of 

 disease or degeneration in the parent hill. Many experi- 

 ments have generally resulted in higher yields from use 

 of large seed cut than from small uncut seed. Even if 

 the small seed is used on part of the field on account of 

 the lower cost, it will pay growers in the northern states to 

 have seed plots in which large cut seed is planted. While 

 the results of the many experiments of the cutting and 

 size of seed are often conflicting some general rules may 

 be stated : — 



(1) The yield to the acre increases with the size of the 

 seed piece up to 50 or more bushels of seed to the acre 

 when the distance of planting is the same. 



(2) The yield to the acre increases with the size of the 

 fraction of the seed tuber from one eye up to the whole 

 large tuber. 



(3) The net yield to the acre above the amount of seed 

 planted and the increased value of seed potatoes kept till 

 spring compared with an equal number of bushels on 

 increased yield which must yet bear the expense of digging, 

 storage and marketing, reduce the size of the most profit- 

 able seed to plant to much smaller size. 



(4) Increasing the number of hills to the acre to- 

 gether with the amount of seed used, while keeping 

 the size of the seed constant, increases the total yield 

 and reduces the yield of the individual hill and the size 

 of the tubers. 



(5) Cutting the same weight of seed to an acre into 

 smaller pieces may or may not increase the yield because 



