1922-23 DEPARTMENT OF LANDS AND FORESTS 199 



felling a tree, and if made up into logs it was closely culled. Afifected logs were 

 called "sinkers"; to what extent this name reflected prejudice remains to be 

 seen. 



If utilizable the question of the floating capacity of red heart rot balsam 

 becomes of the first importance where the timber is transported by waterways. 

 That some of it will float for a sufficiently long time is evidenced by the fact 

 that an appreciable percentage of it can be found in the mill log piles from drives 

 that have lasted up to two years. Knowing of the pains that are taken in the 

 forest to exclude it from the cut, it is a fair assumption that the number of 

 affected logs placed on the skids along the waterways is not greatly diminished 

 by the time the destination is reached. However, this is not a matter for specula- 

 tion, it can be readily determined by direct experiment. To be conclusive the 

 larger the number included in a test the better, they should be intermixed with 

 many sound logs cut from the same area as controls, and at the close of the 

 experiment all the logs employed should be available for checking. 



Red heart rot is very easily recognized in the log, and is not likely to be 

 confused with any other disease of the balsam. The defective wood almost 

 never occurs in the stump, but is found beginning in the main trunk above 

 breast height. Most frequently it centres at about half way up the length of 

 the trunk, and extends from there for long distances in both directions. The 

 affected wood is inclined to be wetter and hence heavier than normal wood at 

 the *time of cutting from living trees. Its colour is a rather bright yellowish 

 brown, often radiately figured or irregularly mottled by lighter less decayed 

 patches, all rendered the more striking by contrast with the encircling outer 

 zone of pure white sapwood. The texture remains remarkably firm for a long 

 time, free from pockets, checks or cavities of any kind, and the wood "fibres 

 out" in shavings very much the same as normal wood. It is of course softer 

 than sound wood and in sawing and chipping greater waste is to be anticipated. 

 Eventually soft streaks develop and there is a tendency towards delamination, 

 but these features are late in appearing. The fibres seem to remain intact for 

 a long time and to retain most of their cellulose. 



The rot enters most frequently by way of dead branches in the lower part 

 of the crown; such branches decay away leaving yellowish rotten stubs — they 

 serve as a means of detecting diseased trees. Infection may also take place 

 through wounds, frost cracks or injured tops. When decay once starts it spreads 

 very rapidly in a vertical direction, and involves almost at once all but an outer 

 zone of sapwood. So it is that a log or bolt may exhibit a fairly uniform stage 

 and amount of the rot throughout its full length. On tracing the rot down- 

 wards in the trunk into sound wood it is found to be continuous with "frost 

 patches" or watery looking areas, commonly evident in balsam at the time of 

 felling; the decay progresses rapidly along these watery streaks which extend 

 continuously for long distances vertically through the trunk. Finally the disease 

 works out to the bark, killing the tree; but the decay continues in dead standing 

 trees or in fallen trunks and slash until all of the wood is involved. Quite com- 

 monly afifected trunks break off, sometimes a short distance from the top but 

 oftener farther down, so that "chicots" or stubs of all heights are to be seen in 

 large numbers throughout a badly infested region. 



The cause of red heart rot, previously unknown, has been determined in 

 connection with our work of the past season. Two years ago inoculations on 

 to artificial media in the laboratory from diseased wood were made which showed 

 at once that the trouble was due to a fungus. Cultures have been maintained 

 ever since for the purposes of study and in the hope that they would fruit, 



