276 
Journal 0} Agricultural Research 
Vol. XXVI, No. 6 
WILT 
While the writer was studying the rootrot Dr. W. A. Orton called his 
attention to another disease attacking udo. The leaves were turning 
yellow, then brown, and drying up. The petioles also died, and usually 
clung to the stalks for some time. Plate 3 illustrates at the right the 
naturally infected plants in Doctor Orton’s garden, and at the left those 
slightly or not at all infected. Plate 4, C, shows a healthy plant in 
blossom, used as a control; B, a diseased plant; A, a plant in an advanced 
stage of the disease. The plants shown in A and B were inoculated four 
months before the photographs were made. 
etiology 
Numerous isolations have been made from diseased plants, and a pure 
culture of Verticillium alboatrum R. and B. was obtained in a large per¬ 
centage of cases. So far as the writer has been able to ascertain, this 
fungus has not been reported heretofore as causing a disease of this host, 
although it is known to attack a considerable number of other plants 
(jo, 7, 5, 2). 
Verticillium was isolated from the diseased tissue of udo, and inocula¬ 
tion experiments were tried to determine its pathogenicity. Udo plants 
grown from seed in the greenhouse were inoculated by inserting hyphae 
and spores from a pure culture into the healthy plant through wounds 
made with a sterile scalpel. The soil was removed from the base of the 
plant to be inoculated, so that the underground portion of the stem and 
a part of the root were exposed; the inoculum was inserted and the soil 
was replaced. Plants similarly treated, except that no inoculum was 
used, served as controls. In one experiment large udo plants growing 
out of doors were inoculated in the same manner as described above. 
On May 23, 1921, 10 plants growing in the greenhouse were inoculated 
and 5 others were prepared and held as controls. On June 18 all of the 
inoculated plants showed signs of the disease. The disease developed 
slowly, and by October two of the plants were entirely dead, while the 
remainder were greatly stunted, had some ’dead leaves, and were very 
low in vigor. Plate 4 shows two of the plants as they appeared in Sep¬ 
tember. The fungus was recovered from about 50 per cent of the dis¬ 
eased plants. In most of the other cases the plantings remained sterile, 
but bacteria grew from a few of them. 
A second attempt to produce infection in udo was made on March 18, 
1922, when 10 plants were inoculated and 5 held as controls. All were 
about a year old, and had been subjected to freezing temperatures 
through the winter. When brought into the greenhouse they grew 
rapidly; by the time they were inoculated they were about 6 inches 
high. On April 5 the lower leaves of six of the inoculated plants began 
to turn yellow and die, and by June 23 most of them were nearly dead. 
Verticillium alboatrum was recovered from four of them. The controls 
remained healthy. 
To test the ability of this fungus to cause infection under field condi¬ 
tions, three large udo plants growing in the field were inoculated in the 
usual manner, and three held as controls. The six plants were nearly 
2 years old, having been started and grown for one season in the 
greenhouse before being removed to the field; they were about 4 feet 
high, and the stalks an inch in diameter. In three weeks the three 
