Larch and Spruce Canker 



red. The cup is not distinctly stalked, but is somewhat 

 narrowed at the point of attachment. The spores are variable 

 in size, ranging from 18 — 25x6 — 8 /x ; paraphyses longer 

 than the asci (Fig. 2, PI. II ). 



The characteristic appearance of canker caused by the fungus 

 is sufficiently familiar to most of those interested in the subject 

 as to require no detailed description. Fig. 1, PI. I., shows a 

 typical canker of small dimensions, with the fungus — ascophores 

 and conidia pustules — natural size. 



The mycelium of the fungus is most abundant in the cortex 

 and cambium region, but it also enters the wood (Fig. 26, 



pi. in.). 



In the great majority of instances, canker commences on a 

 very young stem or branch, in the axil of a dwarf shoot, which 

 was presumably occupied by an aphis " foundress," as already 

 described. Again, when canker is present on a thick trunk or 

 branch, there are almost invariably the remains of a dead branch 

 in the centre of the canker depression. In the axil of the dead 

 branch, which had been partly cracked away from its origin by 

 snow or wind, the spores of the fungus first found an entrance 

 into the then living tissues. 



In addition to the larch and Scots pine, I have also succeeded 

 in producing canker by artificial inoculation on branches of the 

 Siberian larch (Larix sibirica^ Ledeb.), and the Japanese (Larix 

 leptokpis, Endl. ) . 



In the last named inoculation was only effected after much 

 perseverance, and on a seedling placed under conditions very 

 favourable for the inception of the disease. It is quite possible 

 that the Japanese larch would prove immune when growing in 

 the open in this country. 



Spruce Canker, 



Dasyscypha resznarza, Rehm, Ascom. Lojk. Xo. 30 (1882). 

 Syn. Peziza resinaria, Cooke and Phil., Grevillea, III., 185 



(1875). 



This parasite appears to be local in its distribution in 

 Britain, but owing to the fact that to the naked eye, and even 

 when examined with a pocket-lens, it is practically indis- 

 tinguishable from the fungus causing larch canker, and as it 



