FUMIGATION OF CITRUS PLANTS. 

 DARKNESS AND SHADE. 



15 



The effect on plant injury of shade and darkness after fumigation 

 is well illustrated by experiments 10, 12, 15, and 16 which are arranged 

 in Table I for comparison of these influences. 



Table I. — Comparative effects of diffused light and darkness on plants after fumigation 



with hydrocyanic acid. 





Postfumigation temperatures. 



Experiment 10. 



Experiment 12. 



Experiment 15. 



Experiment 16. 



65° F. 



79° F. 



60°F.i 



88°-90° F.2 



63° F.2 



89°- 

 91° F.i 



61°- 

 65° F. 



70°- 

 73° F. 



Darkness 



Shade 



2 

 2 



2 

 2 



2 

 2 



3 

 3 



4 

 4 



3 i 

 3 



4 

 4 



2 



2 



2 

 2 



1 Includes 3 fumigation conditions. 



2 Includes 2 fumigation conditions. 



An examination of this table shows that in none of the several 

 tests included is there any difference hi injury between the plants 

 placed in darkness and those placed in the shade following fumiga- 

 tion. This condition holds equally true at the minimum post- 

 fumigation temperature of 60° F. or the maximum of 91° F. for these 

 experiments. Likewise this situation does not appear to be altered 

 by the temperature of fumigation, for experiments 10, 12, and 16 

 were performed at 61°-64° F. while experiment 15 was carried on 

 at 86°-91° F. 



SUNSHINE. 



The influence of sunshine on citrus plants immediately after fumi- 

 gation is clearly developed hi experiments 10 to 19. Eight of these 

 10 experiments show a decidedly greater injury to the plants placed 

 in the sunshine after fumigation than to those placed in either the 

 shade or darkness at equivalent temperatures. This condition is 

 brought out in Table II. 



Table II. — Comparative degree of injury between plants placed in the sunshine and those 

 placed in the shade or darkness following fumigation. 





Postfumigation temperatures. 



Exp. 

 10. 



Exp. 

 11. 



Exp. 

 13. 



Exp. 14.i 



Exp. 

 16. 



Exp. 

 17. 



Exp. 18.2 



Exp. 

 19. 



79° F. 



65° F. 



79° F. 



80° F. 



85° F. 



70°- 

 73° F. 



70°- 

 71°F. 



85°-90° F. 



87° F. 



Darkness 



2 

 2 



4 











2 

 2 

 4 













Shade ., 



Sunshine 



2 

 4 



2 

 5 



3+ 

 4 



4 

 5 



2 



4 



3 



4 



4 

 5 



5 

 5 



2 



5 





Experiment consisting of two distinct parts. 2 Experiment consisting of three distinct parts. 



