Arisaema rust

[Addison & Richardson]

>1)Does any one know what the alternate host is?  Are alternate rust hosts
usually
>trees/shrubs and will they have the same orange spots?  I haven't noticed
any other
>plant material with similar symptoms but haven't specifically looked
either. How close
>does the alternate host have to be?

According to Pascal Pirone's 5th ed. (Diseases and Pests of
Ornamental Plants) the infecting organism is Uromyces ari-triphylli.  When I
looked this up in his index the only other reference was to a picture of the
rust on a jack.

Perhaps someone with a more detailed fungal reference could look for
more info.  I might try an e-mail to the fungal info service at Ag Canada (I
know the manager).


>
>2)So far, my treatment has been sporadically pulling out infested plants,
obviously not
>an effective solution.  One of the postings said the roots wouldn't be
infected.  Does
>that apply to the corms as well or should they be destroyed?

Pirone says "roots are apparently not invaded by the fungus.  It is
believed that the germinating spores of the fungus may infect young shoots
but cannot reach the corms, which are deeply imbedded in the ground.
Pirone says to pull up and destroy infected plants.  He thinks
spraying with a sulfur fungicide might prevent spread to uninfected plants.
It will not help already infected ones since it is a systemic disease.

In a way, I find this is confusing.  On the one hand he says it is
systemic yet it doesn't infect roots and corms....
but he says to get rid of the whole plant.....I suppose it would be
difficult to cut off the infected parts without contaminating the corm.
>
>3)How far do such air born organisms travel?  If the native population is
infected, is
>there any hope of having a bed of triphyllum 500 feet away uninfected?
>
I'll include this question when I e-mail Ag Canada.

Lois Anne Addison
bedrock.gardeners at sympatico.ca
Dunrobin, Ontario (35 miles west of Ottawa),CANADA
Cdn. Z5; USDA Z4 (lowest temp -40C; highest 37C)