offer an exceptionally good means of determining its effectiveness without 

 the usual hazards. 



A 32 percent solution of sodium arsenite was poured into a jar con- 

 taining cut blotting paper. The liquid was then poured back into the original 

 container. The paper tabs were shaken apart and allowed to dry. A two- 

 inch square of blotting paper thus prepared was found to contain two grams 

 of the chemical. After experimenting with a size and dosage of sufficient 

 strength and convenience for handling, strips two inches long and one-half 

 inch wide were adopted for use. These pieces or tabs can be stored without 

 apparent change, and because they are so thin, are easily slipped into the 

 bark pockets. 



As a test plot for the blotting-paper tabs treated with sodium arsenite, 

 30 trees were marked in a dense white-pine stand of volunteer origin. These 

 trees averaged 30 feet in height, and 3 to 5 inches in diameter. Only one in- 

 sertion was made per tree. All of the trees in the plot displayed definite 

 browning of the foliage in six days. The perimeter of bark affected could 

 easily be seen by the parallel lines extending upward as previously described. 

 These lines were from two to three inches apart. The inner bark occurring 

 between them turned a reddish brown in contrast to normal inner bark which 



p mi- 



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»in^ ■«a«M^. -.1^ ^ «.. 





A white pine treated with a sodium-arsenite tab. 



has a light green color. This band or strip of bark increases slightly in width 

 as it approaches the top with the result that the entire perimeter is encom- 

 passed several feet below the terminal bud. None of the treated trees sur- 

 vived. 



