38 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



For over three years, employment on the work of establishing 

 sample plots up and down the country, has enabled me to 

 collect a number of facts and figures relating to the prevalence 

 of heart-rot. In the establishment of many of these plots, 

 it is customary to make not only moderate, but heavy thinnings, 

 covering the whole range of girth in the stand. One does 

 not usually expect to find badly diseased stems in woods so 

 young as twenty or twenty-five years. Nevertheless, serious 

 heart-rot occurs in woods sometimes as young as fifteen, and 

 even in those species which some claim to be practically 

 immune from the disease, e.g. Douglas fir. An important 

 point is that the rot is not confined to the smaller trees, 

 but occurs throughout the whole range in girth. 



Surely this is silviculturally a point of first importance, that 

 a young wood, which to all outward appearance is quite healthy 

 and growing rapidly, should in reality be attacked by a serious 

 hidden disease. It throws some weight into the balance against 

 those who insist upon the rate of growth and volume-production 

 of species as the one and only consideration in their selection. 



Assuming, however, the extreme importance of volume- 

 production, it must sometimes happen that a stand which in 

 a healthy condition just comes into the economically profitable 

 class, may, when subsequently found to suffer badly from 

 heart-rot, prove to have been grown at a considerable loss. 

 In one case of larch which has come under notice, as much 

 as 6 feet of unsound timber had to be cut from the base 

 of each stem. The importance of this is evident when it is 

 remembered that a very large proportion of the land to be 

 planted up in future, must assuredly be on the border-line ot 

 economic production. This is a point which not only applies 

 to heart-rot, but also to all other serious forest pests. 



Throughout middle-aged and mature stands of Norway 

 spruce and European larch in north-east Scotland, serious 

 heart-rot was frequently found, especially in the dry, sandy 

 soils which occur in that district. It is not uncommon in 

 European larch stands in Morayshire on the glacial deposits 

 which occur there. It should be noted that some of the stands 

 there are otherwise of excellent growth, many being of quality 

 Class III. and several of Class II. On the glacial deposits 

 on a Ross-shire estate, where quality Class I. is not un- 

 common, heart-rot attacks the larch. On the hills, however. 



