224 REPORT OF THE Xo. 3 



IV. Forest Pathology. 



(Eeport of Dr. J. H. FauU for 1920.) 



A greater part of the summer was spent in investigations on the diseases of 

 the timber trees of the Tei:^iagami Forest Reserve. In addition, a short time 

 was occupied with a study of certain hardwood diseases in Algonquin Park, the 

 effect of sulphur fumes in the Sudbury District, and the conditions of mine 

 timber decay and preservation in the Cobalt area. The work in the Temagami 

 Reserve was much facilitated through the many courtesies extended by the Chief 

 Ranger, ]%:tC. E. Hindspn. 

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AODrtlONAL N^OTES OX THE NeEULE BlIGHT OF THE WhITE PINE. 



Alarming reports regarding the discolouration of the foliage of the white pine 

 Iiave been received by the Department in charge of the forests of Ontario at 

 intervals over a long period of years. The attention of the Department appears 

 to have been called to this matter for the first time in 1905, again in 1908, in 

 1912, in 1913, and in 1917. In response to a report from Mr. C. E. ITindson, 

 Chief Ranger of the Temagami Forest Reserve in August, 1912, to the effect that 

 " i\ large number of pine trees in the vicinity of Temagami Lake have turned 

 brown and appear to be dying " a scientific inquiry was promised. Specimens 

 of the injury were submitted to an Experiment Station botanist, but nothing 

 other was done than to venture a guess at the cause ; no attempt was made to study 

 the subject or to give any indication of the seriousness of the malady. 



Following renewed calls for investigation the first observations were made 

 in the Temagami Forest Reserve in the summer of 1918, and they have been 

 continued during the summers of 1919 and 1920. It was soon ascertained that 

 the injury was not a winter killing of the foliage as had been claimed, for it 

 appeared rather suddenly on the new foliage in July, 1918, the whole forest in 

 affected areas becoming tinted as with autumnal colouration. The same phenomena 

 have 1)een manifest wherever this blight has shown itself during the succeeding 

 summers. The investigations of 1919 revealed the fact that the trouble lav in 

 the roots and that in consequence at the time of leafing when there was a sudden 

 demand for an increased supply of water to the crown, the damaged roots were 

 not aide to respond and so the tender new foliage succumbed to a greater or a 

 less extent. 



From a practical point of view it has been important to determine whether 

 or not tlie disease is contagious and to what extent it reduces the yield of the 

 forest. Oliviously the answers to these questions must be taken into consideration 

 in formulatinpf a forestal policy with reference to any affected region. The first 

 prolilom has been decided by direct tests and observations in the negative; the 

 iniurv is phvsiological and not communicable. The second problem is one that 

 cpnnot be solved so quickly and for the reason that we do not yet know to what 

 extent bliffhtin?. is fatal; no one has followed the history of individual blighter! 

 free? in our forests to find out what becomes of them, whether thev recover or 

 die, how long the disease may persist or in case of recovery what loss of Avood 

 growth mav accrue. Such an inquiry demands an annual examination over a 

 =nppe=sion of years of a/large number of marked trees growing under avera-e 

 +vnical conditions. As a firit- step in the solution of the problem several h^ndrel 

 trees were marked in tlie Temagami Forest Reserve in the summers, of "1918 and 



