May 21,1917 
Xylaria Rootrot of Apple 
273 
sought by the cultural methods employed by Crabill and Reed 1 in which 
the carbon-containing compounds cellulose, amygdalin, fibrin, albumin, 
peptone, casein, and asparagin were added to stock agar of inorganic 
salts. Although the fungus grows slowly on nutrient agar, well-defined 
halos had formed within a few days on ca^in and fibrin agar. Aspara¬ 
gin agar, acidified with hydrochloric acid and made yellow by the addi¬ 
tion of rosolic acid, is changed to red by ammonia liberated in the decom¬ 
position induced by the organism. The growth on cellulose, amygdalin, 
and albumin agar indicates that these compounds are not utilized by 
the fungus. Even though a good growth on peptone resulted, no halo 
was formed. The results with casein, fibrin, and asparagin indicate 
that certain proteolytic enzyms (erepsin, protease, and amidase) are 
secreted. 
CAUSE OF THE DISEASE 
Isolations have been made at various times from diseased roots from 
several sources which have constantly yielded an organism with a very 
characteristic mycelial growth. These 
cultures remained sterile until the sum¬ 
mer of 1915, when conidial fructifica¬ 
tions appeared in certain of them. It 
was not definitely proved, however, that 
these conidia were those of the causal 
organism until several months later. 
Stroma tic arms, like those of certain 
species of Xylaria, formed in these cul¬ 
tures (PI. 3). The conidia, too, not 
unlike those of species of this genus, 
were formed either on these arms or on 
elevations arising from the incrustation 
on the surface of the culture medium. 2 
The conidia are hyalin, elongated oval 
in outline, with a blunt truncate pedicel, and measure about 10 by 3 to 
3.5 /x. They are borne singly as lateral buds from the sporogenous 
hypha (fig. 2, b). As yet all attempts to germinate them have been 
fruitless. 
Perithecia have never appeared in any of these cultures, even though 
a variety of media have been employed under several sets of environ¬ 
mental conditions. Perithecial stromata have been found, however, 
upon the roots of trees which had succumbed to rootrot. Thus far, all 
attempts to germinate the ascospores have been unsuccessful, so that it 
has been impossible to determine by growth in culture or by inoculations 
1 Crabill, C. H., and Reed, H. S. Convenient methods for demonstrating the biochemical activity of 
microorganisms, with special reference to the production and activity of enzymes. In Biochem. Bui., 
v. 4, no. 13* P- 3 ®- 44 » pl* 1. *915. 
2 Specimens from cultures were submitted for examination to Prof. George F. Atkinson, who stated that 
the organism was probably a species of Xylaria. 
Fig. 2.— a, Xylaria sp.: Hyphae, showing 
the fusion occasionally noted, b, The conidia 
are hyalin, elongated oval in outline, with a 
blunt truncate pedicel, and measure about 
10 by 3 to 3*5 They are borne singly as 
lateral buds from the sporogenous hypha. 
