FUNGI INJURIOUS TO THE LARCH. 67 



with periods of excessive moisture, in various degrees of combination. 

 Late frosts, or chills which approach such, are among the most deadly 

 agents. The tender tufts of bright green foliage, to which the Larches 

 owe their spring beauty, are usually forced out in this country from 

 a month or six weeks too soon as compared with what occurs in the 

 Alps, etc. and the succulent shoots arid leaves are thus apt to suffer 

 from the sudden oncoming of cold winds or frosts as they slowly drag 

 along their precarious development. Once they get well over this early 

 dilatory period of sprouting, all is safe ; their safety is ensured in their 

 mountain heights by (1) their not beginning to awake from the long 

 winter rest till danger of frosts is practically over, and (2) by the 

 extreme rapidity with which they run through the period of tenderness. 

 Our damp climate, moreover, is calculated to bring it about that the 

 roots of Larches, as of other Conifers, run risks not likely to be 

 incurred in the rapidly drained soils of their Alpine homes. But the 

 conditions referred to thus briefly are just those which favour certain 

 enemies of the Larch at the very time that they are acting prejudicially 

 to that tree itself. 



I have great confidence, therefore, in the well-thought-out view, first 

 put forward, I believe, by one of the most distinguished and able of 

 modern investigators Professor Robert Hartig, of Munich that the 

 appalling liability of the Larch to disease at low altitudes, and in 

 climates which are too moist and variable during the spring and early 

 summer, is due to the co-operation between the factors of the inorganic 

 environment and the directly injurious action of its living enemies. 



The Larch suffers severely from several fungus diseases Agaricus 

 melleus, Trametes Pini, Polyporus sulphureus and others being among 

 them ; but all other forms have sunk into insignificance beneath 

 the overwhelming importance of the "Larch-disease," or "Larch-canker," 

 due to the parasitism of a minute discomycetous fungus known variously 

 as Peziza Wittkommii, Lachnella calycina, Dasyscypha calycina, etc.* 



The main factsf which are of importance to foresters are, that this 

 Peziza develops from its spores a mycelium which, when once it has 

 established a hold in the inner cortex of a branch of the Larch, can 

 go on growing and extending into the cambium ; this it kills, 

 destroying a larger area year by year, and producing the so-called 

 " canker " patch, which is simply a shrivelled mass of dead tissues 

 impregnated with exuded turpentine or resin. If the dead patch 

 extends all round the branch or stem, all the parts above may die 

 off, partly because, the cambium being destroyed, there is no more 

 wood developed at that region to carry up the water supplies to the 

 leaves, and [partly because the resin blocks up the wood w r hich it 

 permeates. 



To understand how it is that the Larch-fungus spreads so rapidly 

 and with such dire effect in Great Britain, it is necessary to note 

 some peculiarities not always properly appreciated. 



Peziza Willkommii, like other fungi, requires merely water, oxygen, 

 and a suitable (not very high) temperature for the germination of its 

 spores ; given these, the germinal hyphsB are developed anywhere. The 

 mere germination of a spore may, therefore, take place on any damp 



* For the synonyms consult Phillips, "British Discomycetes, " p. 241. 

 t An illustrated detailed account of this and similar diseases is given in ' ' Timber and 

 some of its Diseases" (Macmillan and Co.). 



