Bad news--Arisaema

[Plylerd]

You should probably get rid of your infected Arisaema immediately. Your plant
has been infected by the rust Uromyces ari-triphyllia (Common name- Jack in
the
Pulpit Rust), a common rust which  appears on our native plants from June to
September. I have not heard of a cure, although any fungicide could be tried;
sulfur might be effective, although the risk of infection of other plants is
too great, unless you have an intensive care plant room. This name is taken
from the book Mushrooms of Northeastern North America by Alan, E. Bessett,
Arleen R. Bessette and David W. Fischer, three well known mycologists.
Dot in southeastern PA., zone 6 1/2