2 
Journal of Mycology 
[Vol. 10 
PROOF OF THE IDENTITY OF PHOMA AND PHYLLO- 
STICTA ON THE SUGAR BEET. 
GEO. G. HEDGCOCK. 
It has been asserted repeatedly during the past decade by 
leading phyto-pathologists of Europe that the Phyllosticta leaf 
blight and the Phoma root rot of the sugar beet were caused 
by the same fungus, but no cultural proof accompanied by inoc¬ 
ulations has been made to establish the assumption. In order to 
ascertain the truth or falsity of such assertions, and also to try to 
discover if these imperfect fungi do not have perfect forms in 
their life cycle, an investigation was begun three years ago and 
continued intermittently till the present. 
A large number of cultures have been made from sugar beets 
decaying with the typical black crown rot caused by Phoma, and 
from the peculiar concentric brown leaf spots produced by Phyl¬ 
losticta upon the leaves of this plant. Pure cultures were iso¬ 
lated and grown under similar conditions both in test tubes and 
in Petrie dishes upon various agar and gelatin media and upon a 
number of vegetables. In all about fifty sets of cultures have 
been made. Although some variation of cultural characters was 
noted upon different media and under different physical condi¬ 
tions, the cultures from the two sources were similar when grown 
under the same conditions showing no distinct variation of the 
mycological characters, such as the color, dimension, and gross 
appearance of the spores, pycnidia and mycelium. 
For the purpose of more certainly proving the identity of 
the two fungi, sugar beet plants were grown in the green house 
as follows for the purposes of inoculation. Sugar beet seeds 
were sterilized by placing them in concentrate sulphuric acid 
for thirty minutes then washing them thoroughly in sterile water 
and neutralizing the acid remaining in the seed coat by adding 
a ten per cent, solution of potassium hydroxide for a few min¬ 
utes, then again washing in sterile water. These seeds were then 
placed in pots of soil which had been sterilized by heating to ioo 
degrees Centigrade for three hours upon three successive days. 
The plants from these seeds were grown in the greenhouse partly 
in the open and partly in a closed case. They were apparently 
free from either leaf blight or root rot fungi. Twelve plants were 
inoculated with Phoma and twelve with Phyllosticta, a similar 
number being used as a control. Similar leaf spots appeared in 
about three weeks upon both sets of inoculated plants, the control 
plants remaining free from disease. From both sets, leaf spots 
bearing mature pycnidia were taken and the fungus was isolated 
again and grown in pure cultures with the same results as before. 
Beets whose roots were sound and healthy but whose leaves 
were diseased by Phyllosticta were placed during December, 
