RING-SHAKE OF SPRUCE 
This wood-rot of spruce is also common in pine, larch, fir and other 
conifers. It is not known to affect junipers. It has been estimated that 
this disease causes more loss than the aggregate of all the other numerous 
wood-rots. 
SYMPTOMS 
Trees affected by this disease, as in the case of other wood-rots, do 
not show any symptoms externally until limbs begin to die. The fruiting 
bodies of the causal fungus, produced at the broken stubs of limbs or from 
the fissures in the bark, are usually the first signs of disease. 
External signs. Study U.S. Agr. Dept., Veg. Phys. and Path. Div. Bul. 
25, pl. XII and the specimens provided. OBSERVE :— 
1. The various forms of sporophores which constitute the signs 
of this wood-rot. , 
2. The sporophores may be shelving or more or less resupinate. 
3. The sporophores may emerge from broken stubs of branches 
-or from the fissures in the bark. 
Make outline ppawincs from the specimens or plate referred to, showing 
the above points. 
Internal symptoms. In the specimens of transversely and longitudinally- 
sawed wood of spruce affected by this wood-rot; and in plates VI, VII, 
and VIII of the above mentioned bulletin, NoTE :—- 
4. That the first effect on the wood is the red-brown discolora- 
tion. Such timber is said to be ‘‘red-hearted.”’ 
5. That later in the decay-process the color becomes lighter. 
6. That white areas appear here and there in the wood in some- 
what later stages and that these areas gradually increase in number and 
size. DRAW. 
7. That the centers of the white areas are entirely dissolved, 
leaving holes surrounded by white borders. DRaw. 
8. Around most of the holes, a little distance away and usually 
midway between adjoining pockets, a definite black line. DRAW. 
9. That the size of the pockets and the amount of relatively 
sound wood left between the pockets depends on the kind of wood attacked. 
10. That the rotted area enlarges longitudinally in the wood 
much faster than transversely and often the decay involves either partially 
or completely a certain number of annual rings. This is the character 
which gives the name “‘ring-shake” to this wood-rot. 
ETIOLOGY 
The cause of wood-rot known as ring-shake of conifers is the poly- 
poraceous fungus, Trametes Pini Fries (=Porodaedalea Pini (Thore) 
Murrill). 
Life-history. The species of polypores which cause wood-rots of living 
oo similar in all the major facts of their life-histories. (See pages 
_ .The primary cycles are initiated by the basidiospores which are 
wind-borne. 
Pathogenesis. It has been shown that the basidiospores are shot 
from the sterigmata with just enough force in each case to bring them to 
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