MASSACHUSETTS APPLE INDUSTRY. 



37 



;ind were applied in liberal amounts to insure a thorough covering of all 

 parts of the trees. 



The materials were applied each year as "delayed dormant" sprays, and 

 results were determined by microscopic examination of sprayed and un- 

 sprayed trees, the number of dead and living scales present being recorded, 

 (founts were made a few weeks after the sprays were applied, but well 

 before the time of appearance of the crawling young. During the course 

 of the tests more than 10,000 scales were counted, this being the basis 

 upon which conclusions were drawn as to the effectiveness of the different 

 iriaterials and dilutions. 



Preliminary tests the first season indicated conclusively that dilutions 

 of the liquid concentrate of 1 : 16 or beyond would not give satisfactory 

 control of the scale. Further tests at or beyond this dilution were there- 

 fore omitted. The results of the three seasons' tests are summarized as 

 follows: 



Table 2. Results of tests with various sulfur sprays for the control of 



San Jose scale. 



Scale dead. 

 Per cent. 



Lhue- sulfur solution 



97 

 97 

 97 

 95 

 94.-95 

 86-87 



Dry lime-sulfur 



Sodium sulfur compound 



Barium sulfur compound 



93 

 92-93 



90-91 



Unsprayed check 74-75 



It was noted, during the three seasons, that there was considerable vari- 

 ation in the percentage of scale which lived through the winter. This 

 ranged from about 21 to 28 per cent, and seemed closely associated with 

 the type of winter experienced. For the three-year period, the average 

 winter mortality was close to 75 per cent, which figure is doubtless about 

 what we may expect to occur under Massachusetts conditions. 



This difference in the percentage of scales which died during the wmter 

 caused some variation in the estimates of relative efficiency of the sprays, 

 from one year to another. Over the entire period, the relative contro' 

 \ahie of the different sprays as compared with the untreated checks i 

 shown in the following table: 



Table 3. Relative control value of the different sprays. 



Effective Control, 

 Per cent. 

 Lime-sulfur solution 1:8 88 



1:9 88 



1:10 88 



1:11 80 



1:12 80— 



1:14 50 -f 



