1 86 DISEASES OF TREES 



species under the name Exobasidium Rhododendri, produces the 

 familiar " Alpine-rose apples " (Fig. 118) on the leaves of the 

 Alpine rhododendrons. These bear a strong resemblance to 

 many of the galls on oak-leaves which are caused by various 

 species of Cynips, and are to be met with in all Alpine districts 

 where rhododendrons occur. 



TRAMETES RADICIPERDA l * 



T. radiciperda is undoubtedly the most dangerous of all the 

 parasites met with in coniferous woods, not only because it 

 produces the worst kind of red-rot, but also on account of its 

 being the most common cause of gaps in both young and old 

 plantations. I have had the opportunity of observing it on 

 various species of pines, especially P. sylvestris and P. Strobus, 

 and also on other conifers, notably Picea excelsa, Abies pectinata, 

 and Juniperus communis. It is true that I have also occasionally 

 met with its sporophores on the roots of old stools of Betula, 

 and on beeches that 'have been damaged by mice, still I doubt if 

 it occurs on dicotyledons as a parasite. 



Not unfrequently the disease appears in plantations which are 

 not more than five to ten years old, though it also occurs in 

 woods of a hundred years' standing. Here and there indi- 

 vidual trees showing luxuriant growth suddenly become pale, 

 and die. We shall afterwards see that identical pathological 

 symptoms are displayed by trees infected by Agaricus melleus. 

 In the neighbourhood of a tree that has been killed no matter 

 whether it is left standing or has been felled other trees soon 

 die, and so in the course of years the death-circle constantly 

 extends outwards. Large gaps and openings are thus formed in 

 woods which were previously quite close. At first one generally 



1 R. Hartig, Zersetzungserscheinungen des Holzes^ pp. 14 et seq., Tables 

 I. IV. Under the name Polyporus annosus, Fr., a number of different 

 species of fungi have been described, Trametes radiciperda amongst the 

 others. This mode of description has, however, been accepted as sufficiently 

 accurate even in the second edition of Fries's Sy sterna^ which appeared some 

 years after I had described T. radiciperda. The name 7! radiciperda is thus 

 entitled to priority, and is also to be preferred, as it prevents any confusion. 



* [Brefeld, Unters. aus dent Gesammtgeb. der Mykol. VIII., re-names this 

 Heterobasidion anno sum ^ and describes its second kind of spores conidia.- 

 ED.] 



