236 EEPOKT OF THE No. 3 



recovery is not so certain, and is much longer delayed. The following figures 

 drawn from the experiment in the Temagami Forest Eeserve and corrected up 

 to September, 1920, are significant, though some of them are still to be analyzed 

 with respect to severity or lightness of attack, soil, exposure, etc. 



(1) Out of 275 healthy trees of various sizes, noted in 1918 as controls, 

 only 2 are known to have since developed blight. 



(2) Out of 320 trees of all ages on a given area (most of them considerably 

 under 6 inches in diameter, and all counted) 30" per cent, of the stand, or 96 

 trees showed blight in 1918 ; only 5l^ per cent, of the stand, or 15 trees continued 

 to show blight or had been killed by blight at the close of the summer of 1920. 



(3) Out of 147 trees six inches in diameter or less (most of them from 2 to 

 6 inches) blighted in 1918, 8 or 51/^ per cent, of them were dead in 1920, 39 

 or 261/2 per cent, continued to show blight, and 100, or 68 per cent, had recovored. 



An extreme stage of needle blight of white pine. 



(4) Out of 211 trees more than six inches in diameter blighted in 1918, 33, 

 or 15% per cent, were dead in 1920, 156, or 76 per cent, continued to show blight 

 (though in nearly one-half of these with diminished intensity) and 22, or 101/^ 

 per cent, had recovered. 



As a check on temperature conditions a continuous tracing was made with 

 a recording thermometer at Bear Id., L. Temagami, a blight centre, from June 

 24th, 1920, to September 13th, 1920. The minimum temperature for that period 

 was 43 deg. F. on August 22nd, and the maximum 89 dew. F. on August 7th. 



Eighty-seven deg. F. was recorded on June 26th, July 27th, and August 26tli. 

 Forty-eight deg. F. on July 1st was the lowest reading from June 24th to August 

 21st, inclusive. The records of the Federal Weather Bureau at Bear Id. shoAV 

 that the lowest temperature for June was 42 deg. F. on June 7th, and that the 

 last frost, 32 deg. F., was on May 19th. Evidently frost is not a factor affecting 

 pine blight. 



The new needles were just beginning to emerge from the buds on June 21st; 

 there was no indication of blight in them until June 26th, from which date it 



