Help: RUST

[Marge Talt]

Mike, this is what I've been doing with my native populations of A.
triphyllum that exhibit rust.  Hard to do, but I grit my teeth and
remove all foliage with signs of the disease.  While I have not kept
any records, it seems to me the same clumps come back again -
sometimes with rust and sometimes without.  If foliage looks clean on
a clump with some rust on some leaves, I let the clean foliage remain
and often it never exhibits the rust spore....odd.

I figure they have a chance to come back clean and if I left them,
the spore would just spread.  Needless to say, the diseased foliage
goes in the trash and I am very careful not to handle any other
Arisaema or even weed around them without washing my hands first.

So far, knock on wood, my more 'exotic' species seem to be rust free
although many grow in the same neck of the woods as the native clumps
that sometimes exhibit rust.  I'd sure like to know what factors
determine which clumps of A. triphyllum will come down with this in a
given year.  Doesn't seem to have much to do with where they are
growing or whether the season is wet or dry...seems very random.

Marge Talt, zone 7 Maryland
mtalt at hort.net
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----------
> From: Mike Slater <mslater at VOICENET.COM>
> There is at least one alternative to destroying a plant affected
with
> Arisaema rust. (I believe I mentioned this several years ago either
on this
> list or on Aroid-L)
>
> The rust is native to my area on local Arisaema triphyllums.  I
planted an
> A. sikokianum tuber and it did well for several years and even set
seed. In
> the third or fourth year the plant got a severe case of the rust. I
> consulted with Judy Glattstein who is a friend of ours with much
experience
> growing Arisaemas and she told me (as I recall) that the rust is
only in the
> above ground portion of the plant and the tuber is not affected.
She
> recommended that I behead the plant (i.e. cut it off at ground
level) and it
> would likely survive and come back rust free the next year. This
was in
> June, early summer, long before the plant would normally go
dormant.  I took
> a deep breath and did as she suggested. It worked! The plant came
up the
> next year and bloomed (I didn't check it's sex) and lived on for
another few
> years and never had the rust again.  I believe the local outbreak
of rust in
> A. triphyllums had declined as I haven't had and cases in the
garden on A.
> triphyllum for over ten years either.
>
> The only species I have had the rust on are A. triphyllum and A.
sikokianum.
>
> So, if you live in an area with the Arisaema rust present in local
> populations, and thus spores in the air I would recommend you try
the
> beheading procedure.  However, if you live where the rust is
unknown (no
> local Arisaema triphyllum populations) and you have a case in your
garden
> you should probably destroy the infected plants immediately.
>
>
> Mike Slater, Southeastern Pennsylvania, USA, z6