STRENGTH -OF-GAS EXPERIMENTS, 1906-7. 



17 



Table II. — Condition of San Jose scale on unfumigated apples during the winter of 

 1906-7. For comparison with condition of scale on fumigated fruit. 



Date of examination. 



Variety of apple. 



Num- 

 ber 

 of ap- 

 ples 

 exam- 

 ined. 



Num- 

 ber 

 of 

 scales 

 alive. 



Num- 

 ber 

 of 

 scales 

 dead. 



Per 



cent 



of 



scales 



alive. 



Remarks. 



November 12, 1906 



November 26, 1906. . 



Baldwin 



.do 



10 



10 

 10 

 10 

 10 

 10 



10 

 10 

 10 

 10 



559 



572 

 533 

 360 

 102 

 302 



277 



441 



428 

 477 

 640 

 898 

 698 



723 



55.90 



57.20 

 53.30 

 36.00 

 10.20 

 30.20 



27.70 



25.60 



23.50 



.10 



Fruit kept in out-of-door store- 

 house. 

 Do. 



December 13,1906 



February 20, 1907 



February 28, 1907 



December 3, 1906 



December 14, 1906 



December 29, 1906 



January 14,1907 



February 27, 1907 



do 



...do 



Do. 

 Do. 



..do 



Do. 



Rhode Island 

 Greening. 



.do 



Held in cold storage 4 weeks. 

 After Dec. 3 in out-of-door 

 storage house. 

 Do. 



. .do 



256 ! 744 

 235 ; 765 

 999 999 



Do. 



....do 



Do. 



do.. 



Do. 











STRENGTH-OF-GAS SERIES. 



From the first-mentioned or strength series of tests it was desired 

 to obtain information on the strength of gas necessary to kill the 

 scale, and incidentally the possible effect of these various strengths 

 upon the fruit. The apples used were of the Baldwin variety, from 

 western New York (Niagara County) , and badly infested with the scale. 

 The fumigation was done November 12, 1906, with fruit but a few 

 days in cold storage from the orchard and perfectly dry when treated. 

 Ordinary open market baskets were used, of about one-third bushel 

 capacity, and were nearly filled with the infested fruit. Fumigation 

 continued for forty-five minutes. The essential details are given in 

 Table III. 



Table III. — Effect of different strengths of hydrocyanic-acid gas on scales and fruit. Ex- 

 posure, forty-five minutes. (Strength series.) 



Experiment No. — 



Variety of 

 apple. 



Kind of 

 package. 



Rate at which 

 potassium 



cyanid 

 was used. 



Number 

 of scales 

 exam- 

 ined. 



Effect on scales. 



Effect on 

 fruit. 



1 



2 



Baldwin. . 

 ..do 



Jbu. basket. 

 do 



Gr.per.cu.ft- 

 0.05 

 0.10 

 0.15 

 0.20 

 0.25 

 0.30 

 0.35 

 0.40 

 0.45 

 0.50 



3,162 

 1,426 

 1,678 

 1,963 

 3,615 

 3,920 

 2,006 

 2,131 

 1,862 

 2,059 



Many alive 



All dead 



No injury. 

 Do. 



3. 



..do 



do 



do 



Do. 



4. 



..do 



....do 



....do 



Do. 



5 



..do 



....do 



....do 



Do. 



6.. . 



..do 



....do 



.do... 



Do. 



7. 



..do 



..do 



.. do... 



Do. 



8 



..do , 



....do 



do... 



Do. 



9 



...do 



....do 



.do... 



Do. 



10 



...do 



do 



do 



Do. 



From the table it will be noted that all scales were killed without 

 injury to the fruit, at all strengths except where 0.05 gram potassium 

 cyanid per cubic foot was used. In this experiment (No. 1) at first 



