18 



FUMIGATION METHODS 



lows : I had fully expected that the gas would badly 

 injure the trees above 0.75. In fact, no apple trees 

 were injured in the least, even when exposed to 1.45 

 grammes, or about six times the normal strength, 



FIG. 2 OGON PLUM TREE, FUMIGATED WITH THREE TIMES 

 NORMAL DOSE 



excepting one variety, Northern Spy. I can not ex- 

 plain why this was more susceptible to the gas in this 

 test than the others, as it is naturally a hardy tree, 

 and its resisting properties should be as great as Ben 

 Davis or any of the other varieties treated. The 



