44 



The Potato Tuber Moth is not known to occur in Canada. Informa- 

 tion concerning same may be secured by writing to the Dominion Ento- 

 mologist, Department of Agriculture, Ottawa. 



2. Potatoes entirely free from all diseases or blemishes are the ideal 

 potatoes for seed purposes. 



3. When selecting potatoes for planting, all bruised, decayed, exter- 

 nally diseased or unsound tubers should be removed. 



4. Tubers showing Common Scab should, preferably, be all removed. 

 The chances are that scabby seed will produce a scabby crop. 



5. After having removed all externally diseased and otherwise injured 

 tubers, the seed should be soaked in bags or bulk for three hours in a solu- 

 tion of bichloride of mercury, one part in 2,000 parts of water. After 

 treatment, spread out and dry. (See Note 1). 



6. When dry, cutting the potatoes for "sets" will commence. Pro- 

 vide each person engaged with a potato knife, and keep a number of knives 

 in a wooden pail containing a solution of 1: 1,000 bichloride of mercury. 



7. The stem end of the tuber is the seat of several internal diseases. 

 Cut a thin slice off the stem end of each potato; if perfectly sound and 

 free from brown streaks, rings or spots, continue cutting it up to required 

 size. 



8. Discard at once all tubers showing discolouration, when cut as 

 above, at the stem end, and throw out those showing any kind of spotting 

 inside, though the stem end itself may have shown no disease. 



9. Having used the knife on a tuber showing any kind of discoloura- 

 tion inside, throw it at once into the disinfecting solution, and take out 

 another knife before cutting up a new tuber. A knife that has cut 

 through a diseased tuber conveys certain diseases to the new tuber, hence 

 it is very important to change the knife after having thrown out a diseased 

 tuber. It is waste of time to cut out brown spots and use the rest of the 



-tuber. 



After following these precautions, everything has been done to elimi- 

 nate diseases conveyed by unsound seed potatoes. The sets are now 

 ready for planting. 



B. Disease-Infected Land. 



In the case of Powdery Scab and a number of other potato diseases, 

 the causal organism persists in the soil for a number of years; it is, there- 

 fore, necessary to avoid too frequent succession of potato crops. Ordi- 



