INAUGURATION OF NEW CHAIR OF FORESTRY AT CIRENCESTER. 195 



places will be found where it does not occur. The appearance 

 of this fungus makes the planting of larch in future highly- 

 problematic. Great efforts have been made to get at the bottom 

 of this disease, but the results are, up to date, not satisfactory. 

 The Peziza is a wound parasite ; that is to say, the tree must have 

 been injured in some way, to break the bark and let some sap 

 flow out, to enable the spores of the fungus to germinate. 

 Different opinions are held as to how the injury has been caused. 

 Causes have been given as damage by frost, the attacks of the 

 aphis Chermes laricis, hail, wind, and what not. Dr Massie, of 

 the Royal Gardens at Kew, has lately published an article on the 

 subject in the Board of Agriculture's Journal. ^ That article does 

 not contain much which was not known before, but it contains 

 one view which T do not consider correct. Dr Massie maintains 

 that the disease is chiefly due to the damage done by the aphis, 

 inasmuch as the canker generally commences somewhere around a 

 branch, and the aphis mother settles in the angle of the branch 

 with the main stem. This is very ingenious, and I have no doubt 

 that the attacks of the aphis may cause the damage. But, on the 

 other hand, the canker appears where there is not an aphis within 

 miles arotmd. I have just condemned and cleared away a larch, 

 wood seventeen years old because it was ruined by canker, and I 

 have never seen an aphis within five miles of the wood, although 

 I have watched it for the last eleven years. My personal opinion 

 is that we have not yet got to the bottom of the matter, but that 

 probably snow, ice, and wind have more to do with it than the 

 aphis. If heavy snow or rime settles on the tender branches 

 they are pressed down, and probably small rents are caused 

 where the branch joins the main stem. Sap flows out, and gives 

 the spores the means of germinating. It is not improbable that 

 strong wind causes the damage. Unfortunately the result is that 

 the pure larch woods must be given up. The only way to pro- 

 ceed is to plant a sprinkling of larch into other woods. In that 

 case it has a better chance of escaping the disease, and if not it 

 can be cut out in the thinning without ruining the rest of the 

 wood. 



Indigenous Trees versus Exotics. 



To sum up, in my opinion the best plan in economic forestry 

 in this country is : Plant ash, sycamore, and oak on lands which 

 ^ Keprinted in last year's Transactions, pp. 25-36. 



