FUMIGATION OF CITRUS PLANTS. 

 EXPERIMENT 26. 

 -91° F. 



25 



Condition during fumigation, shade, 



Dosage, I2 ounces KCN. 



Date, March 18, 1915, 2.05-3.05 p. m. 



Plants in each test, 2; total, 20. 



Remarks: Temperature of fumigatorium was raised from about 75° to 91° F. im- 

 mediately before fumigation and maintained at temperature of 86°-91° F. through- 

 out the treatment. 



Results. 



Condition before 

 fumigation. 



Condition after fumigation. 



Dark, 63° 

 F. 



Shade, 65° 

 F. 



Dark, 91° 

 F. 



Shade, 95° 

 F. 



Sun, 74° 

 F. 



Dark, 63° F... 

 Sun, 77° F... 



4 



4 



4 

 4 



4 

 4 



4 

 4 



4 

 5 



EXPERIMENT 27. 



Condition during fumigation, shade, 61°-70° F. 



Condition before fumigation, shade, 54° F. 



Dosage, l{ ounces KCN. 



Date, March 30, 1916, 7.12-8.02 a. m. 



Plants in each test, 6; total, 12. 



Remarks: Temperature of fumigatorium was raised from 54° to 70° F. during appli- 

 cation of gas and was held at a fluctuating temperature of 61°-70° F. during treatment- 

 Rise in temperature was accomplished in 2 to 4 minutes. 



Results. 



Condition ailer fumigai ion. 



. Shade, 57° F. 



Sun, 61° F. 



5 



5 



RESULTS. 



The experimental evidence presented in this paper indicates that 

 for citrus trees the safest temperatures surrounding fumigation fall 

 below 80° F. Yet in experiment 27, in which the temperature at no 

 time departed from this optimum, the plants were almost defoliated. 

 Experiments 3 and 8 were conducted with equally tender plants, 

 with the same dosage, with the same exposure in one case though a 

 little less in the other, and at comparable prefumigation and post- 

 fumigation temperatures, yet the plants in these two experiments had 

 merely the tender growth burned. A detailed comparison of experi- 

 ments 3 and 27, however, shows a difference in temperature fluctua- 

 tions during the exposure to gas, it appearing that experiment 3 was 

 performed at a constant temperature of 57° to 58° F., whereas in 



