42 Disease and Death of Trees — Generalities 



the wood body, \\hile the tree can go on rotting for years, 

 to all aj)i)carance.s without detriment, its stability is under- 

 mined, and finally a windstorm may la}- it low in full leaf 

 and otherwise in full health. 



These fungi gain entrance to the wood through wounds 

 made by broken or badly pruned branches, by broken bark 

 or through injured, exposed roots. 



On the ragged surface of a broken branch stump, and 

 even on a well-pruned but unprotected wound, dust and 



water collect and form a seed bed 

 on which the fungus spores — cor- 

 responding to the seeds of other 

 plants, minute or microscopic, 

 easily scattered b}- the winds — 

 can locate and sprout. These grow 

 into the wood by rootlike hy- 

 phcp, which bore through and 

 between cell-walls, branching mul- 

 tifariously and forming a mass of 

 white meshes penetrating the wood 

 Fig 1 2. -"Shelf "fungus or. jj^ ^^^ directions — the so-called 



the stem ot a pine, a, sound 



wood; b, resinous "Hght" mycclium. This draws its suste- 



wood; c, partly decayed ' , ,i ^ i . • 



wood or punk; ^, layer of nance from the tree, oestroymg 

 living spore tubes; e, old cell-walls and absorbing cell con- 



fiiled up spore tunes; f, 



fluted upper surface of the tents. As a conscquencc the wood 



fruiting body of the fungus, , • ^Urjnks cracks turns reddish 

 which gets its food through <^^^^^s, snrmKs, cracKS, turns rtuaisii 



a great number of fine brown, or clsc becomes spongy and 



threads (the mvcelium), its n • i i • '-n^ i • i 



vegetative tissue penetrating yellowish white. 1 he mechanical 

 the wood and causing its destruction proceeds as the mv- 



decay. (Department of '^ 



Agriculture, Division of For- celitim proceeds. 



estry Bulletin, No. lo.) t— n ^- r* 



■^ ' ^ Finally, sometimes after years, 



the mycelium forms a fruit-body on the outside of the 

 tree, the readily recognized toadstool making its presence 



