April, '11] 



LOHRENZ: WOOLLY APHIS 



I 



Third Series 



Sprayed with IS Per Cent Emulsion on October 1 



165 



Deductions from Above Figures 



The first spraying was the most effective. This was due to the 

 fact that the ground was drier, so that the emulsion could soak down 

 to the roots more easily than in the succeeding experiments. Of the 

 total number of trees sprayed, only 87 per cent, or 140 trees were 

 infested. Of these seven showed some Aphis more than two months 

 after the spraying, making 5 per cent infested and 95 per cent freed 

 from Aphis, 20 per cent had become knotty, leaving 80 per cent of 

 the infested stock in good condition for grafting. 



Of the trees in the second and third series it must be remarked that 

 at the time of the last spraying, those in the third series were more 

 infested {i. e., each infested tree had a larger number of Aphis) than 

 those in series 2. This difference was due to the fact that the plats 

 in series 2 were sprayed twice, the first time being three weeks before 

 the last spraying. 



For the second series, where a 10 per cent emulsion was applied 

 first on September 10 and again on October 1, our figures give a total 

 of 103 infested trees, of which 87.4 per cent were freed from Aphis, 

 leaving 12.6 per cent infested after the spraying; 28 per cent of the 

 infested trees were worthless because of the knotty condition of their 

 roots, leaving 72 per cent to be used for grafting. 



Of the 167 trees sprayed with 15 per cent emulsion on October 1 

 fully 90 per cent, or 150 trees, were at that time infested. Fully 133 



•No. 16 had been sprayed with the 10 per cent emulsion on September 10, but 

 without any noticeable effects. 



No. 17 was a plat not sprayed at all. It contained twenty-two trees; of these, 

 five were free from Aphis, seventeen were infested and seventeen were knotty. 



