ROBERT HARTIG ON THE LARCH DISEASE. 19 



II. Robert Hartig on the Larch Disease} 

 Peziza (Helotium) Willkommii. 



The fungus which induces the larch-blister is the cause of one of 

 the most destructive and widely distributed diseases of the larch. 

 It was first described by Willkomm, who, however, made a mistake 

 in its identification, and called it Corticum amorphum. 



Gorticumy in fact, bears only a superficial resemblance to 

 Peziza, and belongs to the Basidiomycetes. On the strength 

 of a macroscopic similarity, also, it was next said to be Peziza 

 calycina, till I recognised that in this fungus we had to do with a 

 newand still unknown species. The ascophore is at once distingviish- 

 able from that of P. calycina by its very short cup-stalk. So 

 much by way of explaining the regrettable confusion of names. 



The larch is a forest tree which thrives splendidly throughout 

 the whole of Germany, suffering but little from frost, at least 

 not more so than other indigenous trees. Originally, however, 

 its distribution was confined to high Alpine regions, because 

 only there could it ofi'er successful resistance to its enemies. 

 Amongst these enemies are to be classed a number of insects, 

 notably the Larch moth, Coleophora laricella. This insect is also 

 found in Alpine regions to a considerable height (over 4000 feet), 

 and so widely is it distributed, and so numerously represented, 

 that it is at first surprising why it does hardly any damage 

 there. This is easily explained from the fact that at high eleva- 

 tions the transition from winter to spring is very rapid, and 

 the development of the leaf-fascicles occupies but a short time. 

 On the plains the larch begins to display green buds even towards 

 the end of March, but their further development is often retarded 

 for a long time, until, in the beginning of May, the growth of 

 the leaves progresses' more rapidly. This is the dangerous period 

 for the larch, because when the caterpillars awake from hiberna- 

 tion they begin to devour the green buds, and when growth 

 proceeds slowly these are largely consumed, and the trees are, 

 for the most part, defoliated. On the other hand, when the 

 leaf-fascicles develop rapidly, a small proportion of the foliage 

 suffices to feed the caterpillars. In Alpine regions the short 



^ Reprinted by permission from Text-Book of the Diseases of Trees, by 

 Professor R. Hartig, of the University of Munich. Ti-anslated by William 

 Somerville, D.CEc, B.Sc., F.R.S.E., F.L.S.; Revised and Edited, with a 

 Preface, by H. Marshall Ward, D.Sc, F.R.S., F.L.S., F.R.H.S. (London: 

 Macmillan & Co. 1894.) This is universally recognised as the standard work 

 on the subject of tree diseases. — Hon. Ed. 



