36 



BULLETIN" 278, U. S. DEPARTMENT OP AGRICULTURE. 



sprayed at each end of the orchard and also in central sections as a 

 basis for comparison with the sprayed. The spray materials were 

 applied while the trees were dormant, April 10, 11, and 13, using a 

 small power outfit. 



To determine the efficacy of the scale insecticides two methods 

 were employed; first, the examination of the scale-infested twigs for 

 dead and live scales by means of the binocular microscope. This 

 method proved to be anything but satisfactory. The second and 

 better method of determining results was the examination of the 

 fruit for scale which crawled thereon. All of the dropped fruit from 

 the count trees was picked up and examined weekly throughout the 

 season. The picked fruit at harvest time was also examined. In 

 Table XIX will be found the results according to variety. Table XX 

 is a commercial summary of Table XIX. 



As will be noted in Table XX (commercial summary), the percentage 

 of fruit (all varieties) free from scale and that with a light infestation 

 has been combined for a comparison with the percentage of fruit with 

 an infestation medium and heavy. The scale upon the fruit classified 

 as lightly infested was usually found more or less concealed in the 

 calyx cavity and, therefore, did not mar the appearance of the fruit 

 for market. Furthermore, a large percentage of the fruit lightly 

 infested had but two or three scales per fruit. 



The fruit with a medium and heavy scale infestation was unmarket- 

 able. Frequently the fruit in the heavy scale infestation class was 

 blood red in appearance and would average 500 to 1,000 scales per 

 fruit. This condition was chiefly found on the unsprayed trees, 

 whose foliage was likewise heavily infested with the scale insects. 



Table XIX. — San Jose scale insecticide investigations, Benton Harbor, Mich., 1914. 





Name and dilution. 



Number of 

 count trees. 



Number of fruits. 



Per cent of fruit. 



Plat. 





Free from scale. 





CD 



C 

 a 

 ffl 



3 



o 



3 



2 







1 

 

 1 



1 



2 



5 

 2 



3 

 3 

 2 



3 

 11 



"53 

 o 

 EG 



3 

 1 



2 











2 



1 





 3 



a 

 K 



6 

 g 



5 



3 

 o 



'5" 

 < 



M 



CD 



cl 



pq 



6 



a> 

 to 

 >-. 







6 

 P 



"3 



"3 

 1 



I 



Liine-sulphur, 1-7 



8 



2 

 

 4 

 6 



4 

 33 



1,841 

 1,717 

 1,008 

 

 1,865 

 946 

 1,531 



1,116 



8,100 



453 

 306 





 435 

 139 







143 



179 

 299 



242 



94 



191 



238 



140 



113 



208 



263 

 1,825 



389 



10 



1,522 











15 



521 





 4,474 



75.667 

 59. 059 

 25. 101 



78.709 

 76.289 

 S9. 877 



S9.247 



52.595 



53.201 

 41.505 



38. 622 

 34.559 



51. 750 



78.77J 

 26.430 



51.24168.637 



II 



III 



IV 



V 



VI 



VII 



VIII 



IX 



(1) Commercial sodium sul- 

 phid, 12.5 pounds-50 



Caustic potash, 11 pounds+ 

 sulphur, 12.5 pounds-50 



(2) Commercial sodium sul- 

 phid, 12.5 pounds-50 



Caustic soda, 11 pounds+sul- 



phur, 12.5 pounds-50 



Limo-sulphur, 1-7+nitfate of 



soda, 50 pounds-50 



Caustic soda, 15 pounds+sul- 



phur, 17.1 pounds-50 



Caustic potash, 15 pounds+ 



sulphur, 17.1 pouuds-50 



20. 215 



30. 892 



32. 774 



41.430 



50.445 



70. 194 



51.716 

 8.056 



90.000 

 39. 490 



SO. 000 

 54. 892 



6.841 









