836 EXPERIMENTAL FARMS 



5 GEORGE v., A. 1915 



to frosl. It must be remembered that the thermometer went to about the centre of the 

 pit in a wooden tube. 



When it was noticed that frost had to some extent touched the stored potatoes, a 

 number of tubers were cut while they were being removed, when it was found that 

 Dehaware showed 20 per cent, Irish Cobbler 10 per cent, Gold Coin 30 per cent, and 

 Carman No. 1 20 per cent of the tubers with the characteristic radiating central die- 

 coloration. In some instances we observed a certain pinkish coloration in the centre 

 of a good many potatoes, but they did not show the typical black heart. On exposure 

 to air these portions turned reddish and then blackish, but were not very clearly defined 

 in outline owing to the turning dark of the cut surface which always occurs on expo- 

 sure to air. After they were taken from the pit these tubers were stored about two 

 weeks in the root-house where the others had been stored over winter. Another exam- 

 ination was then made. From each of the four varieties about twenty-five tubers were 

 taken, without any selection; on cutting them in halves 90 per cent of them showed 

 the typical black heart. We then examined a similar quantity of the same varieties 

 which had been stored since harvest in the root-house. In no single instance did any 

 such discoloration appear When cutting the tubers of the same varieties grown on the 

 same field and harvested under the same conditions. The only difference of treatment 

 was in the storing, those wintered in the pit showing 90 per cent black heart, and those 

 in the root-house with none at all affected. In this connection it is interesting to note 

 that according to Bartholomew a comparatively high temperature of 104° F. will 

 resTilt in what is apparently the same thing as occurred with us, and which we feel dis- 

 posed to regard as frost injuiy. 



The appearance presented by these potatoes taken from the pit is shown in the 

 accompanying plate. 



Potato diseases transmitted hy the use of unsound seed potatoes. — Attention is 

 called here to the publication of a folder showing the principal potato diseases result- 

 ing from the use of unsound potatoes for seed. This folder shows the various diseases 

 in natural colours, which should enable every farmer to determine at once which 

 diseases to avoid when preparing for planting. The drawings have been executed 

 under the Dominion Botanist's direction by Mr. A, E. Kellett, an officer of the Divi- 

 sion of Entomology, who deserves much credit for the artistic skill with which he has 

 prepared them. This publication was printed in an edition of .125,000 copies in 

 English and 40,000 copies in French, and was very widely distributed. Farmers are 

 most earnestlj^ requested to follow the instructions in this special circular, when it is 

 reasonable to hope that potato diseases will soon decrease in virulence. It cannot be 

 said too often that the potato grower is the only person who is in a position to produce 

 a crop which is free from disease. And, naturally, disease-free potatoes will find a 

 much more ready sale than diseased ones which are a menace to the whole country. 



DISEASES OF FRUIT TKEES. 



Apple Canker. — (The following notes on Apple Canker were supplied by Mr. J. W. 

 Eastham, B. Sc.) : 



"About the middle of July, I made an inspection of a number of orchards in the 

 vicinity of Fredericton, N.B., with a view to ascertaining if any injury were being done 

 to apple trees in this vicinity by the Nectria ditissima canker. Although a number 

 of very neglected orchards were visited, many of the trees in which were dying back 

 and in which spraying was never practised, no Nectria ditissima was found. 



" I then proceeded to the Annapolis valley, commencing at the Digby end. 

 Around Digby a few cankers were noticed, but I did not find any orchards here of any 

 size. Around Bridgetown and Annapolis Royal there were a large number of neglected 

 orchards, and in these cankers were found in abTindance. In some cases in young 



Ottawa. 



