rust - a bit more

[Addison & Richardson]

Here is the info that I got from Ag. Canada:
>19 January, 1998
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>Here is the response to your questions as prepared by Dr. Jack Parmelee,
Honorary Research Associate, Biological Resources Program, Eastern Cereal
and Oilseeds Research Centre.
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>Rust on Arisaema.
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>Rust that infects Jack-in-the-pulpit (Arisaema) is caused by the fungus
Uromyces ari-triphylli.  This is an autoecious rust that attacks only
Arisaema and Peltandra spp.  in Canada and U.S.A.  All stages of this rust
are present in its complete life cycle.
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>PYCNIA and AECIA are systemic, and the latter are bright orange, quite
conspicuous, in Spring and early Summer.  As Summer progresses the cycle
continues by forming UREDINIA and finally TELIA as powdery, scattered,
yellow-brown and dark brown sori respectively.  Both these stages are
localized on the leaves and are inconspicuous compared to the systemic aecia.
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>Rust spores are borne aerially and could easily spread a mile or two
depending on climatic conditions.  My experience with other rusts
(Gymnosporangium) indicates that germinating teliospores on Juniperus
virginiana can infect alternate hosts (Amelanchier and Crataegus)
>15 - 18 miles distant.  An uninfected population of Arisaema would not be
safe from rusted plants 500 feet away, but of course the closer to the
infection source the higher the infection rate.  I suggest you rogue out
diseased plants as soon as discovered in the Spring and burn them at once.
This removes the source of infection for nearby healthy plants.
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>Uromyces ari-triphylli occurs widely in southern Ontario, to Quebec and
Nova Scotia and southward into Atlantic U.S.A., as far west as the Dakotas
and south to Florida and Texas.
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>In summary, this rust is limited to Jack-in-the-pulpit and related
Peltandra (also in Araceae) and no alternate host is involved.
>
>Signed J.A. Parmelee, 16/1/98.
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