18 



FUMIGATION OF APPLES FOR SAN JOSE SCALE. 



examination, two weeks after treatment, a total of 13 scales of the 

 942 examined was regarded as alive. At the second examination, a 

 month after treatment, all scales were plainly dead, being discolored 

 and drying up. 



LENGTH-OF-EXPOSURE SERIES. 



In the second or exposure series it was desired to determine the 

 effect on the fruit of various periods of exposure and also the effect 

 of the treatments upon the scales. The variety employed was Bald- 

 win, from the same orchard in western New York, and badly infested 

 with the insects. The fruit was dry when treated and was placed in 

 one-third bushel baskets. The fruit was fumigated November 13, 

 1906, with results as shown in Table IV. 



Table IV. — Effect oj different periods of exposure on scales and jruit. Strength, 0.20 

 gram potassium cyanid per cubic foot. (Exposure series.) 



Experiment 

 Ne- 



Variety of 

 apple. 



Kind of 

 package. 



Rate at which 



potassium 



cyanid was 



used. 



Length of ex- 

 posure. 



Number 

 of scales 

 counted. 



Effect on 

 scales. 



Effect on 

 fruit. 



ll 



Baldwin. . 

 ..do 



Jbu. basket. 

 do 



Gr. per cu. ft. 

 0.20 

 0.20 

 0.20 

 0.20 

 0.20 

 0.20 

 0.20 

 0.20 

 0.20 

 0.20 



3 hours 



2\ hours 



2 hours 



1 J hours 



li hours 



1 hour 



50 minutes . . 

 40 minutes . . 

 30 minutes. . 

 20 minutes.. 



3,360 

 1.968 

 3.047 

 1, 510 

 2,007 

 2,100 

 1,518 

 1,172 

 2,185 

 1,361 



All dead... 



...do 



...do 



...do 



...do 



...do 



...do 



...do 



---do 



...do 



No injury. 

 Do. 



12 .. 



13 



11 



15 



...do 



...do 



...do 



do 



do 



do 



Do. 

 Do. 

 Do. 



16 . 



..do 



...do 



Do. 



17 



18 



19 



20 



...do 



...do 



...do 



...do 



do 



do 



do 



do 



Do. 

 Do. 

 Do. 

 Do. 



It will be noted that all exposures were effective in killing the 

 insects, as determined by the two subsequent examinations, without 

 any injury to the fruit. 



PACKAGE SERIES. 



In the third or package series it was desired to determine the 

 possibility of successfully treating the scales on apples in the original 

 packages, but opened up in various practicable ways. Some of the 

 fruit treated was but a short while from cold storage, and the con- 

 densed moisture on the surface presented afforded opportunity to 

 observe if this lessened the effect of the gas on the insect or contributed 

 to injury to the fruit. Several varieties of apples were used, as Ben 

 Davis, York Imperial, Baldwin, and Rhode Island Greening. The 

 work of fumigation extended over the period from November 14, 

 1906, to January 22, 1907, as stated more in detail in the remarks 

 following the table. Table V presents the essential features of the 

 tests, grouped according to varieties of fruit and character of 

 experiment. 



