562 
Journal of Agricultural Research 
Vol. XXIX, No. II 
An interesting problem in identity 
is furnished by the group of white 
polvpores known as Polyporus anceps, 
Polyporus ellisianus, and a collection 
labeled Polyporus stipticus. All three 
of these fungi were associated with 
white pocket rots in coniferous woods, 
and the rots resemble each other so 
closely that minor differences might be 
ascribed to host relationships. A study 
of the typical stage of the rots in radial 
section shows the ends of the pockets 
usually roughly squared off instead of 
rounded or pointed. The pockets 
often contain black flecks. A char¬ 
acteristic incipient discoloration (fig. 2, 
A) accompanies Polyporus ellisianus 
in Pinus ponderosa (49) but is less pro¬ 
nounced or at times lacking in Picea 
canadensis and Abies balsamea infected 
with Polyporus anceps. This discolora¬ 
tion is prominent in Pinus banksiana 
and Pinus resinosa infected with Poly¬ 
porus anceps. Polyporus anceps , iso¬ 
lated from Picea canadensis , produces 
on inoculated blocks of Pinus ponderosa 
the characteristic reddish incipient dis¬ 
coloration followed by the typical 
white pocket rot. The cultures secured 
from Pinus ponderosa infected with 
Polyporus ellisianus or with Polyporus 
stipticus when inoculated on blocks 
of Picea canadensis produced the faint 
reddish incipient discoloration followed 
by the typical white pocket rot. A 
comparison of the pure cultures on malt 
agar of Polyporus anceps , Polyporus 
ellisianus , and the collection labeled 
Polyporus stipticus brings out their 
close resemblance. A typical char¬ 
acter is the formation, always at the 
upper edge of the slant, of a finely 
poroid growth which usually has a 
narrow smooth margin (PI. 10, A, B). 
This evidence seems sufficient to war¬ 
rant identifying as Polyporus anceps 
the three white pocket rots studied in 
Pinus ponderosa , Picea canadensis, and 
Abies balsamea. 
SUMMARY 
Methods for a complete diagnosis 
of the decays commonly found in 
wood and wood products are present¬ 
ed, with the study of a representative 
number of wood-destroying fungi of 
economic importance. 
Decay and its stages in wood are 
defined and decay processes considered 
in relation to the study. A classifica¬ 
tion under the two main groups of 
white rots and brown rots and their 
subgroups is presented as a workable 
grouping according to gross characters. 
The methods useful in the diagnosis 
of decay are given under the three 
main divisions of gross, microscopical, 
and cultural characters. These when 
carefully determined are believed to 
furnish sufficient data for the identifi¬ 
cation of the causal organism. 
A comparison of the incipient dis¬ 
colorations and zone lines of various 
wood rots indicates the value of these 
gross characters in diagnostic tests. 
The extent to which hyphae penetrate 
the wood beyond the discolored areas 
was determined for some fungi by 
means of microscopical examinations 
and by cultures. Studies of the 
methods of cell-wall penetration, size 
and shape of bore holes, hyphal char¬ 
acters, and general pathological effect 
upon the cell structures have furnished 
evidence of the value of microscopical 
characters, as has also a critical stud}' 
of the manner of penetration of the 
hyphae of Trametes pini in pine wood. 
Cultural characters are found to be 
of great value in diagnostic studies, 
in many cases furnishing the evidence 
necessary to complete the identifica¬ 
tion of the fungus decomposing the 
wood. 
A method is presented which may lie 
used in checking the association of xylo- 
philous fungi with the rots produced. 
The results of experiments showing this 
relationship for certain fungi are given. 
A complete diagnosis of a sample 
of wood will determine whether or not 
decay is present and whether the causal 
organism is alive or dead, and will 
furnish data on the nature of the 
fungus. It will make the detection 
of decay in otherwise sound wood easier, 
and in most cases the cumulative evi¬ 
dence obtained will lead to the identifi¬ 
cation of the fungus causing the rot. 
It is believed that use of the diag¬ 
nostic methods presented will furnish 
data of scientific value for the solution 
of numerous problems relating to the 
staining and rotting of wood and wood 
products. 
EXPLANATORY LEGEND FOR PLATE 10 
A and B.—Pure cultures on malt agar of P. ellisianus isolated from Pinus ponderosa and P. anceps 
from Picea canadensis. Note the characteristic poroid growth with smooth margin in both tubes. About 
natural size. C, D, E.—Types of near-typical sporophores produced on artificial media. X2. C.— 
Lentinus lepideus isolated from Pinus banksiana railroad tie. D.— Lenzites trabea developing a hymenial 
layer which cast abundant mature spores. This fungus was isolated from the brown-rot areas in pine 
post. E —Polystictus hirsutus isolated from birch wood. Identified by typical sporophores attached 
to the sample. 
