Aug. 1, 1925 
Susceptibility of Onions to Uroeystis Gepulae 
279 
which was used for the comparative susceptibility experiments, 80 
to 100 per cent of the seedlings which appeared died before harvest. 
Allium fistulosum L. (Welsh onion). This onion reacts in every way 
like A. cepa , except that the percentage of infection is not so high. 
In the first planting 50 per cent were infected, 5 per cent in the 
second, and 25 per cent in the third. Infected plants succumbed in 
various stages of development. This species is a robust, rapid 
grower, and lives through the winter out of doors. There was no 
difficulty in getting a high percentage of the seed to germinate. 
Zillig also found this species susceptible. 
Allium ascalonicum L. (Shallot). Only one planting was made, 
and about 100 strong plants started growth. Ninety per cent had 
smut in the cotyledons, and those which did not die m this stage 
had smut in the successive leaves and died throughout the summer, 
just as did A. cepa. 
Allium hookem Thwaites. In the first planting 10 per cent were 
infected. In the second planting 95 per cent were infected, and the 
majority of the plants died at an early stage. Sori were found in the 
fourth and fifth leaves, but no smutted plant reached maturity. This 
species seemed just as susceptible as A. cepa. 
Allium libani Boiss. In the first planting 50 per cent had smut, 
and in the second 95 per cent of the cotjdedons had it. A large 
percentage of the plants died in that stage. Only a few showed smut 
in the later stages, and none of the diseased ones developed to 
maturity. 
Allium senescens var. giganteum. About 10O plants started growth 
from the one sowing made. Smut lesions were in the cotyledons of 
almost all of them, and many died in this stage. Lesions also occurred 
in the early true leaves. By the middle of the summer only 15 plants 
had survived, but they were free from smut. This appears to be a 
very susceptible variety and is remarkably different m this respect 
from the rest of the species (if, indeed, this is only a variety of the 
form listed below as A. senescens , the seed of which was received under 
the name of A. fallax). 
Allium Tiuteri Sund. Although a large number of plants came up, 
they all died before the first leaf was fully developed, and all were 
found to be full of smut lesions. This species appears to be so sus¬ 
ceptible that it never gets much past the cotyledon stage in an infested 
sod. 
Allium fiavum L. There was 95 per cent infection in the cotyledons 
of the hundreds of plants of this species, and a heavy mortality at 
this stage. Sori were found in young leaves of some which con¬ 
tinued to live, but no smutted plants were found later in the summer. 
The mortality seems to be all in the young stages. 
Allium schoenoprasum L. (chives), is much more resistant than 
A. cepa. Infection occurred in only about 2 to 5 per cent of the 
cotyledons. Later in the summer sori were found in the leaves. 
Affected plants did not divide and produce tufts of shoots as did 
the healthy ones. All infected ones died before the end of the 
summer. 
Allium schoenoprasum var. sibirieum L. Only two plants came 
up when this seed was planted. One of the two had smut sori on it. 
Allium nutans L. This is a very susceptible species. Two plant¬ 
ings were made, and some hundreds of seedlings came up. Ninety 
