276 
Journal of Agricultural Research 
Vol. IX, No. 8 
of whether or not the tissues were injured. The progress of the disease, 
however, varied considerably. In some cases small areas only had 
become involved in decay within six weeks, and in others the disease 
had advanced several inches to a foot or more beyond the point of inocula¬ 
tion. Even though relatively few inoculations have been attempted, 
the evidence in hand shows beyond doubt that the organism is to be 
regarded as a vigorous pathogene. 
SUMMARY 
(1) A little-known apple rootrot which causes the death of trees has 
been more or less continuously investigated for the past three years. 
(2) It has been observed to occur in six widely separated counties in 
North Carolina and in all probability is the same disease which has 
been observed in sections of Virginia and Pennsylvania. 
(3) The symptoms manifested by the above-ground parts of affected 
trees do not serve to distinguish this disease from other apple rootrots. 
(4) The roots, however, are characteristically covered with black 
fungus incrustations from whose margins radiate minute, black rhizo- 
morphs. The cortex is quickly corroded, and the roots are girdled 
while disintegration of the woody portions proceeds slowly. 
(5) Isolations have constantly yielded a form whose conidial fructifi¬ 
cations and stromatic arms indicate its relationship to Xylaria spp. 
(6) The asdgerous stage of a species of Xylaria has been found upon 
diseased apple roots, but has not been proved to be connected with the 
conidial stage developed in artificial culture. 
(7) Mature mycelium in culture possesses numerous characteristic 
spinulose branches. 
(8) The optimum development of the organism seems to be obtained 
when temperatures of ii° to 13 0 C. are maintained either in the presence 
or absence of light. 
(9) Pathogenicity is established by inoculation with pure cultures into 
the roots of living apple trees. 
