at a height of 13 feet below the tip. They also showed a tendency to increase 

 in width at the branch whorls and around defects. 



Bark removal from the entire tree was easily accomplished. It practical- 

 ly fell off. 



Sample blocks cut at intervals from gray birch treated with sodium arsenite 



tabs. The upward path of killing action shows as dark bands. The top section 



has been encompassed and exhibits decay. 



General Observations 



White pine can be treated with chemical tabs at any time throughout the 

 year. Killing action progresses slowly during the winter months but is con- 

 tinuing and accelerates with rising temperature. Closer spacing of tabs in 

 winter treatment assures more rapid results as the ascending strip of dead 

 tissue produced by the chemical is somewhat less in width than one following 

 the same treatment in summer. Other softwoods may also be treated at any 

 season. 



Hardwoods, because of the difficulty in making bark pockets, are not 

 weJl adapted to winter treatment. 



The wood from chemically killed trees can be used just as in any other 

 dead tree. White pine trees three to five inches in diameter were cut two 

 years after treatment and found to be entirely sound. Red pine deteriorates 

 more rapidly and should be cut for use as soon as convenient after the top 

 shows complete browning. 



The sapwood in most species is subject to stain and decay. Early use 

 of the cut trees is advisable. 



When treated trees are left standing they remain a part of the forest 

 but do not complete for space. It is not necessary to remove them as they 

 gradually decay and ultimately become a part of the forest litter. 



13 



