144 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



selectors should have a thorough knowledge of tree diseases, 

 and be acquainted with the situation and extent of every infected 

 area. The collection of seed from diseased specimens should 

 not be allowed. Yet many thousands, perhaps millions, of 

 larch trees( Larix Europced) have in the past been raised from 

 seed collected from diseased specimens. We need not, therefore, 

 be at all surprised if the constitution of the larch shows signs 

 of weakness and lack of disease-resisting powers. Really 

 nothing else could be expected. The continued use of seed 

 collected year after year from large numbers of diseased trees 

 has, in all probability, undermined the constitution of the larch. 

 Vast numbers of trees which fell easy victims to disease 

 (Dasyscypha calycind) were allowed to reproduce their kind, 

 until a strain of trees has been brought into being which is 

 peculiarly susceptible to the inroads of disease. If seed from 

 perfectly healthy trees had always been used, it would have 

 gone a very long way towards preserving the constitutional 

 robustness of the larch. As many tree diseases — such as fungus 

 diseases — are infectious, and may be easily carried along with 

 the seed, every precaution should be taken, so as to prevent 

 the use of seed collected in areas or forests in which infectious 

 diseases abound. In fact the collection of seed in such areas 

 or woods should be prohibited : " Prevention is better than 

 cure." 



With regard to point 4, I think a mature tree in the prime of 

 life will, as a rule, produce more vigorous seed than an immature 

 tree or one which, through old age, is verging on collapse. 

 The using of large quantities of seed taken from very old or 

 very young trees should, as a rule, be avoided, notwithstand- 

 ing the fact that some trees may produce good seed as soon as, 

 or immediately after, they reach the seed-bearing stage. Until 

 trees attain maturity it is difficult to judge their qualities of 

 endurance, adaptability, and timber production. A mature 

 parent tree may be considered as having "stood the test," 

 while a young parent tree has not, and may be the first tree in 

 the wood to succumb to any severe test of endurance, such as 

 a long spell of drought or an exceptionally severe winter. 

 So there must be a safety in selecting mature parent trees. It 

 is a well-known fact that early or abundant seed-bearing some- 

 times indicates constitutional disturbance or failing health. A 

 very old tree has certainly " stood the test," but old age has 



