146 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



The early primary symptoms of disease are very widely 

 spread, and Dr Albert found them on upwards of 90 per cent, of 

 all farm-land grown Scots pine. They are easily recognised in 

 the shape of dark or black spots on the still living roots, which 

 in these places contain a more or less decomposing fluid, and 

 frequently exude resin. The first appearance of these symptoms 

 was usually observed on the wide-spreading surface-roots, en- 

 tirely unconnected with each other, thus showing that the disease 

 starts simultaneously in many places. Numerous entirely dead 

 roots were also found in every case. The fact that practically 

 every Scots pine tree grown on old farm land suffers from a 

 root disease, seems to have been proved, but that this disease 

 kills a large proportion of the trees it attacks is at least doubtful. 

 The actual slayer is, unquestionably, Polyporus annosiis or one 

 of its relations. At what period of the original root disease this 

 scourge begins to take an active part in the work of destruction, 

 and in what condition the roots have to be to allow it to thrive, 

 are questions which merit the most careful investigation. With- 

 out this secondary attack, a regeneration of the root-system — 

 though this remains marked with numerous scars — seems mostly 

 to take place ; with it death is the inevitable fate of the tree. 



The root-system of the Scots pine growing on farm land is 

 quite different from that of forest-grown trees, for though the 

 ' young plant develops long tap-roots, these are mostly smooth 

 like a carrot, without bifurcations or branches, and the side- 

 roots — which start from the very root necks — keep almost 

 entirely in the upper layer of the soil. This may be because 

 they find easily assimilated food near the surface, and experience 

 more difficulty in penetrating the soil, which is denser than nature 

 intends them to penetrate under ordinary circumstances. Dr 

 Albert suggests that this surface position of the roots exposes 

 them to periodical and rapid changes between excessive moisture 

 and drought, thereby starting the disease. He may be right, 

 and the reasons he gives for his belief are not without value ; but 

 here we enter the field of speculation, and we must leave it to 

 physiologists and mycologists to ascertain the exact nature of 

 the primary disease and the course it runs. All I think we can 

 safely accept is, that on the Continent a primary pine root disease 

 is universal on all afforested farm lands ; whether, however, the 

 disease is as active in England is a matter for inquiry. The soil 

 conditions must be subject to the same laws, but it is conceivable 



