No. 6. DEPARTMENT OF AGRICULTURE. 361 



SELECTION ON THE BASIS OF A PARTICULAR NUMBER OF SALABLE 



TUBERS TO THE HILL 



Practical growers know how the number set in each hill varies 

 with each season. In 1914 the set in my field was small, and the 

 tubers large. In 1905 there were too many in the hill and the crop 

 ran small. In 1910 one field had a small set and another planted 

 with the same seed the same day but with a light sandy soil set 

 nearly twice as many to the hill. 



EARLY REMOVAL OF WEAK AND DISEASED HILLS 



Most potato diseases reduce the yield of the affected hills. Remov- 

 ing hills with fusarium wilt, black-leg, leaf-roll, curly-dwarf, etc. 

 leaves a healthy seed stock which will give a better yield the next 

 year than if the diseased hills are left. Particularly is this true 

 where small seed is planted, as diseased hills produce many small 

 tubers. Some of these diseases also infect the soil and attack pota- 

 toes for years after. This digging must be done before the healthy 

 tops die. Work is usually not pressing at this time. The extra ex- 

 pense is small as these hills would have to be dug and picked up 

 later anyway. 



THE TUBER-UNIT METHOD 



Good sized tubers are taken from the bin of as near the same size 

 as possible. These are quartered lengthwise and planted in adjoining 

 hills. When dug all are piled together. This method has an ad- 

 vantage over any other in that one can begin in the spring and have 

 clear proof of seed transmission of pla^t characters the same season. 

 This method of quartering all seed is objectionable after the first 

 year because of different strains varying greatly in size. The quar- 

 ters from the strains which have only a few large tubers to the hill 

 will give a better start to their plants than those from the strains 

 with a larger number of medium sized tubers to the hill. As these 

 large potatoes are worth less per bushel, this method increases the 

 proportion of poorer yielding and less valuable potatoes. There is 

 also considerable labor and trouble in keeping units separate. Other 

 objections are that some growers are liable to pay more attention 

 to getting a particular tuber type and to large vines than to yield 

 and sale value. 



DIGGING BY HAND AND SAVING THE BEST HILLS 



This is especially adapted to the immense proportion of our crop 

 dug by hand. Where machine diggers are used the seed should be 

 dug before the crop is ripe enough to dig without bruising by the ma- 

 chine, unless late blight is known to be in the field. In that case the 

 seed may be dug later on days when the ground is too sticky from 

 rain to use the machine. It is certain in Europe and probable in this 

 country that immature seed yields better than that allowed to be- 

 come fully ripe. The only extra expense over ordinary hand digging 

 is a little care in keeping hills separate and that of going over the 

 rows and picking up the best hills first. While some may be better 

 because of a better chance on fertile spots it is very unlikely that 

 any seed will have the same luck two years in succession. So the 

 second year will throw out all except those that yield well because 



