LIBRARY) 3 



111 



BOTANY. \yjfc S ^A : 



Edited by John Craig. 



Potato Rot. -The advantages of spraying potatoes with the 

 Bordeaux mixture for the prevention of potato rot are well shown on the 

 experimental plots now being dug at the Central Experimental Farm. 

 The dry weather which prevailed throughout August and in the begin- 

 ning of September gave conditions very unfavourable for the develop- 

 ment of the parasitic fungus (Phytofihthora infestans, De By.), which causes 

 potatoes to rot ; but the advantage, to those plants of which the foliage 

 was kept green for some three or four weeks longer than on the 

 untreated plots, is plainly shown by the far larger crop and the much 

 better tubers. The reason of this is, of course, quite plain. On the 

 untreated plots the leaves the starch-making organs of the plant 

 were destroyed by the potato rust (which is merely another form of P. 

 iuje$ta?is) just at the time when they were required to collect and 

 manufacture starch to be afterwards stored up in the tubers. In the 

 case of the treated plants, on the other hand, these organs were 

 preserved by the application of Bordeaux mixture and kept on performing 

 their proper functions for another month, at the time of the year when 

 this was of most importance to the crop ; moreover, had the weather 

 been wet during August and September it is probable that, not only 

 would there have been a difference in tne size of the tubers on the 

 untreated plots, and consequently in the number of bushels reaped, but 

 a large proportion of these would have been rotten. J. F. 



Spraying to prevent Fungous Diseases. Much has been said 

 and written upon this subject since the practice was recommended some 

 six years ago. Much remains to be learned, but great progress has 

 been made, and the orchardist of the future will view spraying to pre- 

 vent fungous and insect attacks in the same light, as bearing upon the 

 success of his fruit crop, as the intelligent grower of to-day does the 

 important operations of cultivating and manuring. 



Very satisfactory results have been attained by the horticulturist of 

 the Experimental Farm in treating apples and pears for Fitsidadium 

 dendrilicum " scab " or " spot ", and Monilia fructigena " soft rot " on 

 plums and cherries. A comprehensive series of experiments was 



