358 



Scientific Proceedings, Royal Dublin Society. 



Table T. 



Development of Pliytophthora rot in sprayed and ibnsprayed potatoes in Prince 



Edward Island, Canada. 



It is evident that the sprayed plots (which, incidentally, gave an increased 

 yield) showed a considerable reduction in the amount of diseased tubers, the 

 average for the untreated plots being 6'7 per cent., and that for all the sprayed 

 plots 3'2 per cent. The crop from each plot was placed separately in a 

 storage cellar, and the potatoes were again sorted at the end of November. 

 The result was then reversed, the potatoes from the sprayed plots showing on 

 the average more than three times as much disease as those which had no 

 treatment. This result was comparatively uniform throughout all the twelve 

 plots, and, on the whole, the potatoes which were sprayed oftenest had the 

 greatest amount of tuber rot, those sprayed less often had less, and the 

 unspiayed plots had considerably the least. So great was the amount of 

 disease which appeared after the potatoes were stored that it much more 

 than neutralized the original advantage (so far as tuber disease is concerned) 

 resulting from spraying. 



