THE SILVER FIR. 357 



frost and drought for 10 and sometimes even 20 ^-ears. This 

 is given either by the mother trees or by an artificial shelter- 

 wood of larch, Scotch pine or birch. This period passed, the 

 tree is comparatively free from danger. Storm and snow may 

 do damage, but not nearly so much as in the case of spruce. 

 Cattle and deer nibble it, and the latter sometimes peel it, but 

 it heals such damage easier than the other conifers. Squirrels 

 bite off the leading shoots. 



Insects are, on the whole, not very destructive. Two species 

 of Tortrix (T. iiinnuaiui and riifiniifrana) destroy the needles 

 and shoots, especially in Central Europe. A weevil, Pissodes 

 })ice(e, peculiar to this species, is destructive chiefl}^ to sickly 

 trees. The wood-wasps {Sirci^ and some T<»mcld(f' bore into 

 the wood, especially when newly felled. A scale insect is 

 likely to attack young silver fir, whenever it is grown without 

 shelter. 



Mistletoe is frequently found on silver fir, perforating the 

 wood and reducing its value. 



Of Fumji, J'^cidiiim datintim, Lk., must be mentioned, 

 which causes witches' broom and canker on the silver fir ; 

 this evil occurs sometimes on a large scale. To meet it the 

 diseased stems should be cut out as soon as possible. Of 

 other fungi, Pliytophthora omnivora, Pestalozzia Hartif/ii, 

 Agariciis mdh'tts and Tminetes radiciperda may be mentioned, 

 but they do less damage than in the case of spruce. 



The silver fir stands j)r»»/??_r/ well. 



If silver fir is mixed with other species, it should be care- 

 fully watched, as it is liable to be outgrown and injured owing 

 to its slow growth during early youth. 



Thinnings rarely need commence before the 25th or 80th 

 year ; they should be light until the woods enter the last third 

 of their life, when they should be heavy, so as to cause the 

 remaining trees to increase rapidly in diameter. Throughout 

 the thinnings, and especially the early ones, all trees infected 

 with canker should be removed, even if by so doing the leaf 

 canopy should be temporarily interrupted ; in many cases it 



