June 14, 1924 
Leaf Rusts of Rye and Barley in the United States 
1123 
continuous. On November 10, when last observed, the plants were covered with 
a heavy development of aecia and, even then, many newly-formed pycnia were 
evident. Although the rusted straw remained as a mulch throughout the winter, 
and the Anchusa plants produced vigorous growth the following spring, no 
infection was observed. In the fall of 1923, the same plants again were mulched 
with rye straw laden with teliospores of Puccinia dispersa. No infection resulted. 
This would indicate that, if its aecial host be present, the leaf rust of rye occa¬ 
sionally may produce its aecia in abundance in this country in late summer and 
fall just as it does in Europe. Also the indications are that the absence of its 
aecial host apparently has not destroyed in any way the inherent ability of the 
rust to produce aecia. 
At the time Anchusa officinalis was mulched with rye straw, other boragin- 
aceous species in close proximity also were mulched with the same material in 
order to determine whether the rust might not have still other aecial hosts. 
These Boraginaceae were Nonnea rosea Link, N. lutea DC., Cerinthe minor L., 
C. major L., C. alpina Kit., Lappula echinata Gilib. (Myosotis lappula L.), 
Myosotis palustris Hill, M. arvensis (L.) Hill, M. alpestris F. W. Schmidt, 
M. virginica (L.) BSP., Symphytum asperum Lepechin ( S . asperrimum Donn) 
and Pulmonaria officinalis L. All these plants were exposed to infection equally 
with the plants of Anchusa officinalis , but in only one case was there any indica¬ 
tion of infection. One plant of Nonnea rosea developed a few pycnia but the 
infection proceeded no further. This additional link in evidence points to the 
identity of the leaf rust of rye in this country and in Europe, for Eriksson (4) in 
Sweden found that Myosotis alpestris and Symphytum asperrimum were immune, 
while pycnia developed on Nonnea rosea . 
Earlier in July, 1920, a new host for the leaf rust of rye was discovered in 
Anchusa capensis Thunb. This had been planted as a border plant around 
flower beds near the horticultural greenhouses of Purdue University. The 
plants showed a fairly heavy development of aecia (PI. 1, B) the spores of 
which, when sown on rye, produced typical uredinia of the leaf rust of rye. 
As this sporulation occurred in advance of the application of the straw mulch, 
the infection must have started from a small plat of rye to the north, or perhaps 
from straw contained in the manure used in fertilizing the bed. This seems to 
be the only record of the occurrence of aecia of the leaf rust of rye in this country 
except where Anchusa plants had been planted and mulched for the purpose 
of obtaining the aecia. Flowering specimens of this species of Anchusa were 
sent to Prof. B. L. Robinson of the Gray Herbarium, Harvard University, who 
kindly had them compared with an isotype of Anchusa capensis and reported 
that they appeared to be identical. 
It is not probable, however, that the aecial hosts of the leaf rust of rye are of 
much importance in this country at the present time. The aecia, with one 
exception, as stated above, have only been found where Anchusa plants have 
been mulched with rye straw for the purpose of producing the aecia. Lycopsis 
arvensis , presumably the Anchusa arvensis of northern Europe, occurs in 
North America from Nova Scotia to Ontario, Minnesota, Pennsylvania, and 
Virginia. So far as we have been able to determine, aecia of Puccinia dis¬ 
persa have never been collected on this species. Since Puccinia dispersa over¬ 
winters fairly commonly in the uredinial stage on rye, the rust maintains itself 
without the aecial stage. 
It hardly would appear probable that, were the development of the aecial stage 
in this country to occur in the fall, as it does in Europe, conditions affecting main¬ 
tenance of the rust would change to any extent. The rust would have to survive 
the condition either in the aecial stage on Anchusa or, what is more probable, pass 
