CHAPTER IV. 



NEW DISEASE OF POTATOES. 



Peziza postuma, Berk, and Wils. 



IN the beginning of the month of August 1880, Mr. 

 Ambrose Balfe, secretary to the Boyal Horticultural 

 Society of Ireland, reported to us a disease then invading 

 certain crops of potatoes in the west of Ireland, in a 

 manner hitherto unknown to him. The potatoes had 

 been bought as " Champions," and planted in land which 

 had been reclaimed from bog eight years previous to the 

 outbreak of the disease. When the ground was reclaimed 

 a coat of clay was spread over and incorporated with the 

 soil. For the first three years potatoes were grown, fol- 

 lowed by a year of oats, next the ground was sown with 

 grass and meadowed, and lastly "champion" potatoes 

 were planted. In preparing the ground for the potatoes 

 sea-weed was first spread over the grass, and ten days 

 afterwards it was covered with farmyard manure. The 

 potato sets were laid on the manure, and then covered. 

 Ridge planting was adopted. No doubt the mode of 

 culture was defective, as it is bad in practice to place 

 potato sets in immediate contact with decaying vegetable 

 matter and farmyard manure ; such materials always con- 

 tain an immense number of disease germs both of animal 

 and vegetable origin. The manure used for potatoes 

 should always be old and thoroughly decayed, and it is 

 perhaps best that the cut faces of the sets should be 

 allowed to dry before they are planted. Some planters 

 pass the cut surfaces rapidly across a hot iron with good 

 effect, but others maintain that it is better to place the 



