48 TKAXSACTIONS OF KOVAL SCOTTISH ARBORICULTURAL SOCIETV- 



yellow-browns, and the final colour was, in most cases, some 

 shade of yellow, although often intermixed with reddish tints. 



" A long period — at least a month — was required for this 

 sequence of colour changes ; and, at the end of this time, 

 in case the disease had proved fatal, the whole plant was stiff, 

 dry and entirely dead." 



It was observed that the disease occurred in more or less 

 irregular patches scattered throughout the beds, and that the 

 diseased patches were almost always situated in slightly sunken 

 portions of the beds, as well as along their margin where 

 drainage was poorest. A careful investigation failed to reveal 

 the presence of any pathogenic fungus. 



For the following reasons the author concludes that the 

 disease is due primarily to unfavourable soil conditions : — 



" I. Repeated attempts to isolate from the roots a pathogenic 

 fungus or fungi as causal organisms in the disease were always 

 attended with negative results. These experiments consisted 

 of (i) incubation in moist chambers of roots which had recently 

 died, (2) insertion of the inner portions of diseased roots, 

 removed with a sterile scalpel, in nutrient agar, and (3) placing 

 such roots, whole, in nutrient agar. In every case no forms 

 appeared except saprophytic fungi, and bacteria which were 

 presumably saprophytic. One fungus, which was kindly 

 identified by Mrs Flora W. Patterson, Cylindj-ocladium scopanu?n, 

 Morgan, 1 was of such general occurrence that it was viewed 

 with suspicion, but inoculations of healthy seedlings in sterilized 

 soil with this form gave only negative results. 



" 2. The soil of the seed-beds was stiff and clayey, and although 

 a considerable amount of leaf-mould had been added to it, there 

 was still a very small proportion of humus. As a consequence 

 its porosity was slight, and in rainy periods the water would 

 stand for some time in the hollows and poorly drained parts. 

 Such conditions would naturally prevent a free access of oxygen 

 to the roots, and would therefore readily promote root rot. 



" 3. The disease caused most havoc during the months of 

 March and April, when the soil was still soggy from the 

 winter freeze and rains, and when the roots, on the other 

 hand, stood in the greatest need of oxygen for the commence- 

 ment of metabolic activities incident to the season's growth. 



1 Morgan, A. P., "Two new genera of Hyphomycetes," Boi. Gaz., 17, 

 190-192, 1S92. 



