IQ2 FUMIGATION METHODS 



leakage and by surface condensation on the walls of 

 the box, or rather by solution in the film of moisture 

 adherent to the walls. 



Effeft of moisture on foliage. "Experiments 

 were designed to show the effect of moisture adherent 

 to foliage. A quantity of maple and cherry leaves 

 were held under a hydrant, then shaken to remove the 

 excess of water and placed in the diffusion box. The 

 amount of adherent water was about two and three- 

 quarter pounds. In each trial a fresh lot of leaves 

 was used, and a mechanical mixer or fan was used to 

 complete the diffusion. Two trials showed an average 

 of 54 per cent, as compared with 72 per cent, obtained 

 without the wet leaves, or, with the wet leaves, just 

 three-fourths as much acid vapor is diffused through 

 the atmosphere of the box as without them. This is 

 significant as v indicating the effect of wet foliage. The 

 amount of acid vapor available for killing insects is 

 diminished and the amount acting directly on the 

 plants is increased." Thus the necessity of having 

 plants either in the nursery or orchard as dry as pos- 

 sible. 



Absorbent effect of fresh earth. "In this experi- 

 ment the bottom of the 2g-cubic foot box was removed 

 and the box was placed over fresh soil; the soil was 

 thoroughly packed or tamped around the edges. The 

 surface soil thus exposed was i^ x 13^ feet, or about 

 20 square feet. The mechanical mixer was used, as 

 noted above. The two trials, with closely concordant 

 results, show an average of 44.5 per cent, of the normal 

 amount of acid vapor as compared with 72 per cent, of 



