Murphy — The Sources of Infection of Potato Tubers. 363 



hand, with plots dug in the ordinary way late in the season. This is a very 

 noteworthy point. That potatoes which were left in the ground exposed to 

 blight infection from spores washed down into the soil for an added period 

 varying from twenty-one to thirty-four days should decay less than potatoes 

 not so exposed points to some incompleteness in the generally accepted 

 theory of tuber infection. 



V. — EiELD Experiment on the Sources of Tuber Infection 



IN Ireland. 



In view of these results it was thought advisable to try a similar 

 experiment in Ireland. While it is probably true that storage rot is seldom, 

 if ever, as severe in this country as in portions of Eastern Canada, neverthe- 

 less loss due to this cause is hardly ever absent, and in some cases it becomes 

 quite serious. 



Portion of a field of Up-to-Date potatoes at the Albert Agricultural 

 College, Glasneviu, Dublin, measuring twenty-five square perches, was 

 selected for the work. This area was divided into thirty-three equal plots. 

 Each of the eleven methods of treatment indicated in Table IV was tried in 

 triplicate on these plots, which were distributed as uniformly as possible 

 over the experimental area so as to minimize inequalities in the blight and 

 soil conditions. Different treatments were given before and after digging, as 

 detailed in the table, the dates of digging being there indicated. Before 

 being stored, the potatoes were most carefully sorted and all diseased and 

 small tubers excluded (except in the case of plot 8). The remainder were 

 stored in small pits in the open. Each pit contained about 2^ cwt. of 

 potatoes, representing the yield of each series of three plots. The pits were 

 made in the usual way, very slightly sunk in the ground, the potatoes being 

 covered lightly with straw, or, in certain eases, with potato stalks. Where 

 old stalks were purposely used for covering they were replaced with straw 

 after a few days. All the pits were finally covered with earth. They were 

 opened and the potatoes again examined on February 15th and 16th, 1921. 



[Table IV. 



