FREEZING INJURY TO POTATOES WHEN UNDERCOOLED. 



Russet Rural, and Green Mountain. They were all held at 40° F. 

 previous to experimental use. 



Storage tests on the seven varieties held at temperatures below the 

 true freezing points were conducted in order to correlate, if possible, 

 the freezing points (Table I) of these varieties as determined by the 

 thermoelectric method described by Wright and Harvey (9) and the 

 actual freezing of the different varieties in storage. These tests were 

 conducted at 28° and 25° F. The higher temperature was chosen 

 because it represented about the minimum degree of undercooling to 

 which the potatoes could be subjected, since it was just below the 

 freezing points of most of the varieties used. The lower tempera- 

 ture was chosen because it was far enough below the freezing points 

 of all varieties to represent a definite degree of undercooling at which 

 freezing quickly follows a very light inoculation. When the potatoes 

 were selected for the freezing tests they were placed in small wooden 

 baskets holding from 8 to 10 specimens, in order that they might cool 

 down without much delay. At the conclusion of each test the potatoes 

 were removed, to be held at ordinary room temperature for about 24 

 hours before being cut longitudinally for examination. If cut imme- 

 diately after being removed from storage, no evidence of freezing 

 injury will be apparent unless they have been frozen solid. Unless 

 specially noted, all injury reported is of the vascular type, as de- 

 scribed by Jones, Miller, and Bailey. 



Table I. — Freezing points of seven varieties of potatoes. 



Variety. 



Freezing 

 point. 



Variety. 



Freezing 

 point. 



Triumph 



°F. 



29.04 



29.66 



29.33 



29.64 





°F. 



28.70 



Irish Cobbler 





28.32 



Spaulding No. 4 





28.50 



ATTierir.an Giant ... 













Tables II and III show the results obtained from these tests at 28° 

 and 25° F. The data presented in Table II show that potatoes did 

 not freeze to any serious extent when exposed to 28° F. for many 

 hours. In experiment No. 1 two specimens of each variety were held 

 seven hours, one specimen of Rural New Yorker being injured. In 

 experiment No. 2 twenty specimens of each variety were held 24 hours. 

 Only two varieties showed injury. These included two specimens of 

 Irish Cobbler and one specimen of the American Giant. In the third 

 experiment two specimens of each variety were held 48 hours, one 

 Rural New Yorker being injured. In experiment No. 4 half -bushel 

 lots of Triumph, Spaulding No. 4, American Giant, and Russet Rural 

 varieties were held in bags for 48 hours with no injury. In experi- 

 ment No. 5 eleven specimens of each variety were held for 70 hours. 



