LARCH AND SPRUCE FIR CANKER. 31 



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

 leptolepis, 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 qiiite possible 

 that the Japanese larch would prove immune when growing in 

 the open in this country. 



Spruce Canker. 



Dasyscypha resinaria, Rehm, Ascom. Lojk. , No. 38 (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 indistinguishable 

 from the fungus causing larch canker, and as it has been gener- 

 ally considered that the last-named disease was always due to 

 the presence of Dasyscypha calycina, it is quite probable that 

 Dasyscypha resinaria is frequently passed over as D. calycina. 



In this country D. resinaria is most frequently met with on 

 the spruce {Picea excelsa, Link), and has occurred in Shropshire, 

 Yorkshire, Surrey, and Hants. It is also not uncommon on the 

 larch (Larix europcea, D.C.), where it occurs either alone or in 

 company with D. calycina. Quite recently D. resinaria has 

 proved very destructive to the Bhotan pine (Pinus excelsa, 

 Wall.) in Wiltshire. 



On the Continent D. resinaria has been recorded fx'om 

 Germany and Hungary, a parasite on the spruce fir^ whereas 

 in the United States this fungus causes great injury to Abies 

 balsamea, Mill. 



Like D. calycina, D. resinaria is a wound-parasite, and is 

 frequently enabled to enter the tissues of a living tree through 

 wounds made by another minute parasitic fungus, a species of 

 Exosporium (Figs. 20-25). 



I have proved by cai-efully-conducted inoculation experiments 

 on seedling spruce, that the Exosjjorium is a true parasite ; its 

 spores, when placed on the open bark of seedlings or the young 

 branches of old trees, can germinate and pierce the bark and 

 pass into the inner actively-living tissues, provided the atmo- 

 sphere remains damp, until the spores have germinated and the 

 germ-tube passed into the interior of the branch. 



