450 
Journal of Agricultural Research voi. xxvi, no. xo 
Quite often the sapwood shows scattered, irregular patches of red 
stain which end abruptly at certain annual rings. These isolated stained 
areas are interpreted as individual infections originated through the 
wounding of the cambium by sapsuckers. The brighter tints of red are 
more commonly found in these areas. 
The absence of hyphae in many instances in the outer borders of the 
discolored area leads to the belief that the coloring matter spreads 
through the wood ahead of the hyphae. 
PATHOLOGICAL ANATOMY 
Eidam, referring to the red stain in boxelder, states that if mounts 
are made of transverse and longitudinal sections taken from the red areas 
of the wood then the parenchyma cells are seen to be frequently pene¬ 
trated by a fungous thread which is colorless, the walls of the tracheids 
are so corroded that they easily fall to pieces, and particularly in the 
large pitted tracheids of Acer negundo (the fungus threads) weave matted 
cushions of large anastomosed hyphae filling the cells completely. 
A preliminary study of the material so far collected on boxelder 
indicates that the fungus is to be classed as a stain organism rather than 
as a wood destroyer. Microscopical examination of radial sections of 
the red colored wood taken from infected branches reveals the fact that 
the outer regions of the colored areas rarely contain hyphae. Oc¬ 
casionally, in the central area of the branch, where the fungus has been 
present for some time, hyphae were found in the vessels and in the pith 
cells. Penetrations of the pith cell walls were noted. In the pith the 
hyphae are irregular in size, rarely branched, and of a jasper pink to 
ochraceous salmon color. 
No evidence of corrosion of cell walls such as observed by Eidam was 
noted in the material so far studied. Whenever corrosion was observed 
it was invariably attributed to the decay-producing organisms accom¬ 
panying the red-stain fungus. A Myxomycete, which apparently feeds 
upon the hyphae of the red-stain fungus, is often found associated with 
the red stain. The question arises whether this Myxomycete may not 
be responsible for the scarcity of the hyphae of the red-stain fungus in 
the wood. 
GEOGRAPHICAL DISTRIBUTION 
The geographical distribution of this disease may be assumed to coin¬ 
cide with the range of the boxelder. The disease is widespread in this 
country throughout the States of Wisconsin, Minnesota, Michigan, and 
South Dakota. Few reports of its occurrence have been received from 
regions outside of the Middle Western and Southern States. It is com¬ 
monly met with in the raw material of the slack cooperage industry. In 
Tennessee, where the writer visited a large cooperage mill, the boxelder 
bolts could be picked out of a carload of mixed stock by means of the 
vivid red color in the heartwood and sapwood. From published data a 
similar stain in boxelder appears to occur in widely separated countries 
in Europe. 8 
ECONOMIC IMPORTANCE 
Since the red stain in the wood infected by this Fusarium constitutes 
a blemish, 9 the grade of such stained material is considerably lowered 
• Eidam E. op. cit. 
• According to standard grading rules a blemish of this type consists of a stain either superficial or deep 
in the wood which is not sufficiently objectionable to be classed as a defect. 
