366 CONNECTICUT EXPERIMENT STATION REPORT, IQI2. 



Often, after trees are cut, the stumps of those infected at 

 the base develop a vigorous growth of the fruiting stage on 

 the three or four outer rings of wood. This probably means 

 that the mycelium can penetrate thus far into the wood from 

 the canker, or possibly it may mean that fresh infection takes 

 place from spores developing in the nutrient material furnished 

 by the exposed sapwood. 



After an infected tree has been killed, or has been cut 

 before death, there may be" a further development of the 

 fruiting stage of the fungus. We doubt, however, if disease- 

 free trees often develop prominent infection after cutting. In 

 other words, the fungus is parasitic or semi-paraskic, but does 

 not develop in its prime as a saprophyte. Even on trees killed 

 suddenly and left standing, Plate XXII b, we have often failed 

 to notice a general spread of the fungus through the bark. 

 In the wood pile, too, while the fruiting stage no doubt shows 

 some increase, a general subsequent infection of the disease-free 

 bark does not seem to lake place. 



As to the Fungus. The mycelium of the fungus ramifies 

 through the bark, beneath it, and often into the wood for a 

 short distance. When the epidermis of a young, smooth, 

 cankered branch is carefully peeled off, it often shows the 

 mycelium as a whitish or yellowish coating just beneath, and 

 below this is the reddish-brown diseased bark sharply marked 

 off at its edges from the healthy white tissues.. In the older 

 infected bark, the mycelium is sometimes seen as fan-shaped 

 areas between the tissues or on the wood. The mycelium often 

 gives a mottled effect to the bark as seen when cut through. 

 In time, with the aid of insects, it produces soft, semi-dusty 

 spots in the firmer, less affected tissues. 



The infected tissues do not show external signs of the fungus 

 itself at first (with artificially inoculated cankers, not for two 

 months or more after inoculation, Plate XXV b), but in the 

 smooth bark in time numerous fruiting pustules are gradually 

 protruded through small, lenticel-like openings. These at first 

 are quite small, but in time show as subspherical to irregularly 

 oblong cushions one-eighth of an inch or less in length and 

 about that in height, XXIV c. In the rough bark they break 

 out more irregularly from the crevices, and are more run 

 together into compound groups, XXIV d. They vary in color 



