Nov. io, 1923 
Two Diseases of Udo 
273 
The two fungi also have the same appearance in culture and have the 
same maximum, optimum (22-25 0 C.), and minimum temperatures. 
Besides this, when udo was inoculated with an authentic culture of 
Sclerotinia libertiana , a disease was produced which was similar in every 
respect to that caused by the Sclerotinia from udo. 
Attempts to develop the apothecia from the sclerotia have been made 
several times during the past two years. Sclerotia of different sizes 
which had developed in the host or in culture were buried in or placed 
upon sand in small flasks, tumblers and crystallizing dishes. They 
were then kept moist and held in diffused light at room temperatures 
(15 to 25 0 C.) for several weeks. Similar trials were made at different 
times of the year in order to subject the sclerotia to different conditions 
of temperature and light. Sclerotinia libertiana sclerotia develop apo¬ 
thecia very abundantly in Florida, where they seem to find conditions 
very favorable during the autumn and winter months. A small quantity 
of the sclerotia taken from udo were therefore sent to Dr. I. C. Jagger, 
at Sanford, Fla., who placed them under what seemed to be ideal con¬ 
ditions for the development of apothecia by sclerotia of Sclerotinia 
libertiana. Here sclerotia of the latter held under the same conditions 
as controls developed apothecia, while the sclerotia from udo did not. 
At Berkeley, Calif., in the winter of 1922-23, sclerotia, produced by an 
authentic strain of 5 . libertiana , isolated by Jagger from an apothecium 
grown on Irish potato agar, together with sclerotia from parallel cultures 
of the fungus from udo, were placed in moist sand and on filter 
paper in tumblers and held for several months at room temperature 
(15 to 25 0 C.) in diffused light. In about a month the sclerotia of 5 . 
libertiana produced apothecia in abundance, both in the sand and on 
moistened filter paper, while those of the Sclerotinia from udo failed to 
produce apothecia, even after several months. Since the writer has 
been unable to obtain the ascigerous stage, the fungus from udo could 
not be definitely determined. It is safe to say, however, that it is very 
similar to Sclerotinia libertiana and is probably a strain of this fungus. 
PATHOGENICITY 
As stated above, the fungus has been isolated a number of times 
from the diseased host tissue. It has also been obtained by disinfecting 
the sclerotia formed in or on the diseased parts of the host with equal 
parts of 95 per cent alcohol and mercuric chlorid solution (1 to 1,000), 
washing in sterile distilled water, and then planting them on agar. The fun¬ 
gus thus obtained has on several occasions been inserted through wounds 
in the host and infection obtained. In these experiments the soil was 
first removed from the base of the plant, a wound was made with a 
sterile scalpel in the root or underground part of the stem, and mycelium 
from pure culture was inserted in the wound, which was then closed 
as carefully as possible and the soil replaced about the plant. In some of 
the experiments hyphae were laid against the uninjured root and covered 
with moist soil. Control plants were treated in the same manner in 
each case, except that no inoculum was used. Plants of different ages 
were used in these experiments, some being only a few weeks' old and 
others more than a year old. Isolations were made and the organism re¬ 
covered in practically every case. The fungus isolated was again inserted 
in the host, infection obtained, and the fungus reisolated so that 
Koch's rules of proof were fully carried out. For details of some of the 
experiments see Table I. 
