THE DISEASES OF CONIFERS. 



141 



So recently as 1888,* Von Tubeuf has discovered a disease 

 on this Fir which may prove very troublesome in wet districts. 

 The tips of the branches droop, and their leaves fall off, but 

 remain hanging by means of a greyish mycelium, which holds 

 them together as if attached to the tips by means of spiders' web. 



This mycehum gives rise to sporopliores and sclerotia, which 

 prove it to be a Botrytis \B. Dotiglasii, n. sp.), and if it turns 

 out to be as destructive as some of its congeners (e.g., the 

 Botrytis of the Lily-disease t), foresters will certainly have to 

 reckon very seriously with it. 



The damage is done by the mycelium penetrating between 

 the cells of the leaves and young shoots, and killing the tissues 

 forth^-ith. One source of danger is that this fungus can live as 

 a saprophyte in the dead foliage, &c., on the ground, as well as 

 parasitically in the living shoots ; and that it develops very 

 efficient resting organs, known as sclerotia, which enable it to 

 tide over unfavourable seasons. 



It appears that this Botrytis has also been observed on the 

 Larch, and on Silver and Spruce Firs. 



It is as yet too soon to attempt to decide as to the extent of 

 the danger with which the fungus threatens us ; we know very 

 little, moreover, as yet, as to the capabilities of the Douglas Fir 

 itself in this country. Perhaps the greatest damage so far done 

 to it is by winds, but for my own part I feel that this Conifer is 

 still too new to the British Islands i to be finally reported upon, 

 and it is not surprising that we know as yet very little about its 

 diseases. 



It is with the Firs as with the Pines, as regards the large 

 numbers of diseases due to fungi : the American list is very 

 long, and our own is by no means either short or exhausted. 



The Hemlock Fir, Silver Fir and Spruce suffer in Germany 

 from a leaf- fungus [TricliosplicEria ]jarasitica) which reminds 

 one in many respects of some of our Erysipheoi. The seedlings 

 of these and other Firs are destroyed by Pliytoplitliora oiiini- 

 Tora and by a Pestalozzia lately re-examined by Yon Tubeuf. 

 Almost as I write § comes the announcement of another 



* " Beitr. zur Kenntniss d. Baum-Krankli." (Berlin, 1888), 

 t See "Annals of Botany," vol. ii., 1888, " A Lily Disease." 

 % I am told that it tvas only introduced in 1826. 



§ Zeitschr. f. Pflanzenkrankli.," B. i., H. B, 1891, p. 179; see also B.i., 

 H. 1, 1891, p. 47. 



