Aug. 1, 1925 
Susceptibility of Onions to TJrocystis Oepulae 
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CLASS 3 
Allium voThynicum Bess. Two plantings were made. Ten per 
cent of those of the first planting had smut in the cotyledons, and 
50 per cent of the second planting had it. No lesions were observed 
in the true leaves. 
Allium polyphyllum Kar. and Kir. Two plantings were made, 
but the germination was poor. Only six plants were obtained. 
Smut lesions occurred in the cotyledons of half of them, and some 
died later, but the writer is not sure that the smut killed them. 
Further tests might place this species in class 1 or 2. 
Allium scorodoprasum L. Same general condition as for the 
preceding. Only a few plants came up, but some of them had lesions 
m the cotyledons. 
Allium obliquum L. Of several hundred plants which came up 90 
per cent had infected cotyledons, but the later leaves showed no sori. 
Allium senescens L. (. A.fallax Schult). Out of about 150 seedlings 
from the first planting, smut lesions were found in only five cotyle¬ 
dons. In a second planting, 2 per cent of the cotyledons had smut. 
No lesions were observed in any of the leaves, and it was not observed 
that any of those which had smut in the cotyledons died. Appar¬ 
ently here is a very resistant species, but not immune. 
Allium ampeloprasum L. Only a few seedlings were obtained. 
About half of them had sori in the cotyledons. 
Allium darwasicum Reg. Only 14 seedlings resulted from the one 
planting made. Three or four of them had smut lesions in the 
cotyledons. 
Allium montanum Sib. and Sm. Twenty seedlings grew from the 
one planting. Two of them had infection in the cotyledons, but 
no infected ones were observed later. 
Allium paradoxum Don. Of the three plants which came up, one 
bad cotyledons lesions, but no disease was observed in later stages. 
Allium odorum L. Three plantings with seed from as many 
different sources were made, and hundreds of plants were grown. 
No smut was observed in any of them. The results were at variance 
with those reported by Zillig, who was able to infect this species. 
Subsequent to the thircl planting, Zillig kindly sent some seed which 
he obtained from the Botanic Gardens in Munchen. When plants 
grew from these, about 10 per cent had lesions in the cotyledons, 
this suggesting the possibility that in this species we may have 
varieties or strains which differ in their susceptibility to the smut 
organism. 
Allium recurvatum Rydb. Of the 50 plants which came up, one- 
half had smut in the cotyledons, but no lesions were observed later 
on the true leaves. Although many of these plants died in a young 
stage, it was not evident that the smut was the cause. 
CLASS 4 
Allium oreoprasum Shr. Two plantings were made, and hundreds 
of seedlings grew, but no smut sori appeared on any of the parts at 
any time. As far as these trials showed, this species is perfectly 
immune. 
Allium moly L. Only one planting with this species was made. 
The germination was poor, and only a dozen plants were obtained; 
