April, '19] 



APPLE APHIS: DISCUSSIOX 



143 



spray. The same year that this failure occurred we made a laboratory 

 test to determine the minimum dosage which would destroy the rosy 

 aphis. At the time the test was made the rosy aphis was present in all 

 stages from the slaty colored stem mother to the winged forms. The 

 results of that test are shown in the following table: 



Effect of Nicotine Sprats on Rost Aphis 



The following year we laid out some blocks of seven-year-old apple 

 and made the series of treatment indicated in the following table: 



Summary of Resvlts in .\phis Control ExPEP.mENT 



Note. — Unsprayed trees showed average of 000 aphis per 100 buds. 



A large blo';k of trees of the same aze and variety in the same orchard were sprayed with lime-sulfur (1 to 9) during 

 dormancy. These trees showed an average of aj'his to ICO buds. 



Mr. John Barclay of Cranbury was the orchardist cooperating and 

 the man who personally made the treatments. Throughout my entire 

 experience I have never seen an orchardist or an entomologist who 

 made treatments any more thoroughly than Mr. Barclay and I believe 

 therefore that the data obtained are reliable. This table shows that 

 the spray of winter-strength lime-sulphur to which 40 per cent nicotine 

 was added at the rate of 1 to 1000 left fifteen times more living aphis 



