1 905-] 



Rottinc; of Potatoes. 



677 



The fungus of Winter Rot is undoubtedly very common 

 among potatoes which have rotted in the pit. In the early 

 stages it produces softening and swelling in tubers, which are 

 later attacked by bacteria and show " wet rot." Experiments 

 in the prevention of these two diseases were conducted at the 

 Garforth Farm belonging to the Agricultural Department of 

 Leeds University in 1903-4, the effects of dusting with quick- 

 lime and slaked lime at the rate of 7 lb. per cwt. being tested 

 on if cwt. of sound potatoes mixed with 28 lb. of infected 

 potatoes stored in pits for twenty weeks. 



Of the two kinds of lime used there is no doubt that lime in 

 the " quick " condition is preferable. Potatoes dressed with 

 " slaked " lime in all cases turned out sticky, the lime adhering 

 to them as a pasty mass, and, on drying, the lime became so 

 firmly attached that it was not removable in the ordinary pro- 

 cesses to which potatoes are subjected in preparing them for 

 market. When quicklime was used, the condition of the potatoes 

 was quite different. A dry shelly case had been formed by the 

 lime around each tuber which readily became detached from 

 the skin, leaving it clean and bright. 



It would seem from the results obtained in these experiments 

 that in " pieing," either for seed purposes or for consumption 

 in spring, lime may be profitably used to prevent loss. Tubers 

 affected with brown discolourations go very readily to " wet 

 rot," and " wet rot " itself is communicable to sound and healthy 

 tubers. Lime in either of the forms used, while it does not 

 prevent the brown tubers from going rotten, yet prevents in- 

 fection of surrounding tubers and the spread of "wet rot," which 

 is the worst enemy that threatens the " pies " in winter. 



It is rather remarkable that there should be any difference in 

 the condition of the potatoes treated with quick and with slaked 

 lime. It is well known that quicklime in contact with air con- 

 taining moisture rapidly becomes hydrated or slaked, and the 

 ultimate product is the same in each case, whether quick or 

 slaked lime is used, and the potatoes might be expected to turn 

 out equally dry from all those " pies " where lime was used. 



The explanation offered in the Report is that in the cases 

 where quicklime was used the moisture necessary for slaking 

 was obtained in the " pie " from the skin of the tubers with 



