1919-20 DEPARTMENT OF LANDS, FORESTS AND MINES. 131 



'Chief Ranger, who had accompanied me when these trees had been located, covered 

 tOur course again in August and forwarded a report, backed up by specimens, 

 [showing that the same four trees were again badly blighted, and one other in the 

 [game neighbourhood. 



Turning to the Timagami Forest Reserve, where in some areas a large per- 

 [centage of the trees of all ages had shown the blight in 1918, and where extensive 

 observations had been made, the results afford surer ground for the conclusions 

 ; arrived at. The trees examined fall into three general classes — young trees . with 

 [trunks up to 3 or 4 inches in diameter; large trees, many of them mature, with 

 trunks 10 inches and upwards, and those that lie between. In the first instance 

 it was found that there had been a general recovery. Thus on Island No. 976 

 where 75 per cent, or more had been affected in a count of all the young white 

 pines on the eastern half of the island — a total of 400 trees, not more than 10 per 

 cent, displayed blight this year. Those of the middle class exhibited greater 

 variation. Some were again severely blighted, while others showed no signs of 

 blight, and between these two conditions there were all grades. Almost invariably 

 the recovered trees of this size were clothed with abnormally short needles, and 

 often the foliage was scantier and paler than in healthy trees. The large trees, 

 however, showed less than 1 per cent, recovery, and there was a mortality of about 

 5 per cent. Likewise there were scattered cases in this class of trees of what 

 appeared to be new instances of blight; at all events, some vividly blighted trees 

 were numbered for the first time that had been passed by in 1918 — probably 

 because of uncertainty as to their condition at that time. 



A renewed effort has been made to discover the cause of " needle blight." 

 As there are no causal organisms to be detected in the affected crowns, several 

 hundred inoculations were carried out on healthy twigs of healthy trees with the 

 juice from diseased foliage. Certain so-called physiological diseases are known 

 to be contagious and such disorders have been communicated in this way. No 

 results followed. The season before interlocking diseased and healthy branches 

 of contiguous trees had been grafted at the point of contact. An examination 

 showed that the branches had formed an organic union but that the virus, if there 

 be one, had not been transmitted. The bark was then carefully examined through- 

 out the entire extent of trunk and roots of diseased trees, and then stripped and 

 the exposed wood examined. No indications of disease were manifest. The first 

 signs of organic trouble were discovered in the root tips. 



An examination of root tips of trees is an arduous business. Two methods 

 were followed. First, the root system of a six inch blighted tree was exposed 

 by carefully following the main roots outward from the base of the trunk care- 

 fully disentangling the branches and picking away the adhering soil and vegetation. 

 Secondly, several isolated small blighted trees with trunks one to three inches in 

 diameter were removed in their entirety from the shallow rock sub-soil character- 

 istic of that region, and a number of healthy trees of similar size as checks. The 

 root systems of these trees were carefully washed free from soil by vigorous im- 

 mersion in water. A study of the cleaned roots located the seat of the trouble. 

 The roots of the check trees were normal, the root tips were white, frequent and 

 vigorous. By contrast the tips of the main branches of the root system of the 

 diseased trees were almost invariably killed back from 4 to 12 inches or more. 

 Some of the smaller lateral branches were not so clearly dead, but few appeared 

 in good condition, and not one healthy main root tip was uncovered in the entire 

 lot. It was at once apparent that the absorbing areas of the root system had 



