2 26 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



poplar are in pure blocks. All sections have been successful,, 

 especially that of the white alder, which affords an interesting 

 demonstration of the possibilities of this species. Its density 

 and volume are surprisingly good, while the black poplar 

 runs it very close. The soil of the glen is of a clayey nature 

 and very wet : but these hardwood trees are rapidly rectifying 

 the excessive wetness. They appear to maintain an even, 

 balance of moisture throughout the seasons. 



There are numerous places similar to this glen where little 

 use can be made of the soil, without continuous and costly 

 draining ; the outlay involved would scarcely give an adequate 

 return. But in this case the trees are improving the drainage 

 of the soil by the penetration of their roots. They are also- 

 improving its fertility by leaf-fall and added humus content. 

 Up to the present time these hardwoods have given better 

 results than might reasonably have been expected of conifers, 

 and with a continuance of the skilful treatment they have- 

 received in the past their future should be assured. 



30. Studies in the Pathology of Young Trees 

 and SeedHngs. 



{With Plates.) 



By Malcolm Wilson, D.Sc, F. R.S.E. , F.L.S., Lecturer in 

 Mycology, University of Edinburgh. 



I.— THE ROSELLINIA DISEASE OF THE SPRUCE. 



In the present series it is proposed to describe some diseases- 

 of seedlings and young trees caused by fungi, and also to deal- 

 with injuries caused by mechanical means during planting and 

 cultivation. 



A serious outbreak of the disease which forms the subject 

 of the present paper was investigated over fifteen years ago by 

 Dr Borthwick, who has kindly handed over to me a number of 

 the diseased seedlings as well as his notes made at the time 

 of the outbreak. I am, therefore, indebted to him for a large 



