20 



BULLETIN 907, U. S. DEPARTMENT OF AGRICULTURE. 



EXPERIMENT 22. 



Condition during fumigation, shade, 58° F. 



Condition before fumigation, shade, 59° F. 



Dosage, 1^ ounces KCN. 



Date. March 30, 1916, 8.15-9.05 a. m. 



Plants in each test, 3; total, 18. 



Remarks: Plants in a slightly resistant condition. Maximum sun temperature 

 76° F. Plants were removed from fumigatorium to cool shade for the period elapsing 

 before placement into sunshine. 



Results. 



Condition after fumigation. 



Shade, 

 60° F. 



Sun, 66° F., 

 exposed 

 at once. 



Sun, 67° F., 

 exposed 

 after 30 

 minutes. 



Sun, 68° F., 



exposed 



after 1 



hour. 



Sun, 72° F., 

 exposed 

 after 2 

 hours. 



Sun, 74° F., 

 exposed 

 after 3 

 hours. 



1 



4 



3 



3 



3 



2 



EXPERIMENT 23. 



Condition during fumigation, shade, 65° F. 



Condition before fumigation, shade, 68° F. 



Dosage, 1| ounces KCN. 



Date, March 30, 1916, 12.03-12.53 p. m. 



Plants in each test, 3; total, 18. 



Remarks: Plants in a slightly resistant condition. They were removed from 

 fumigatorium to cool shade for period elapsing before placement into sunshine. 

 Maximum sun temperature, 76° F. 



Results. 



Condition after fumigation. 



Shade, 

 71° F. 



Sun, 76° F., 

 exposed 

 at once. 



Sun, 77° F., 

 exposed 

 after 30 

 minutes. 



Sun, 76° F., 



exposed 



after 1 



hour. 



Sun, 74° F., 

 exposed 

 after 2 

 hours. 



Sun, 71° F., 



exposed 



after 3 



hours. 



1 4 



3 



3 



2 



1 



In each of these four experiments all plants were removed from 

 the fumigatorium immediately after exposure, part being placed at 

 once in the sun while the remainder were held in the shade. Those 

 plants which were exposed to the sunshine at different periods follow- 

 ing fumigation were held in the shade at a cool temperature (60° to 

 70° F.) between the time of their removal from the fumigatorium 

 and placement in the sunshine. Some plants were held continuously 

 in the shade at certain temperatures as a check on the injury attribu- 

 table to direct sunshine. 



It is seen by an examination of experiment 20 that the dosage used 

 merely injured the very tenderest growth where plants were placed 



