Stagnospora curtisii

Mary Sue Ittner
Sun, 16 Mar 2003 22:59:24 PST
Dear All,

I was looking through some of my saved messages to see if I could come up 
with something to write for the Wiki Disease page on Stagnospora and how to 
treat it to go with Jennifer's picture of her sick bulb. I found a couple 
of messages from people in our group to other forums so I am repeating them 
and wondering if anyone has anything else to add:

 From Den Wilson.

"It is almost certainly Stagnospora curtisii and a scourge of Hippeastrum.
Fortunately, it rarely attacks other Amaryllids apart from Narcissus,
although I have seen very slight traces on some Rhodophiala but never on any
others. Not all Hippeastrum species are susceptible but those that are can
be badly disfigured. It is not easy to cure (I hope somebody contradicts me
on this) and is most active in cool damp weather when it manifests itself as
the familiar bright-red patches affecting any part of the plant from roots
to flowers. As the weather warms the fungus ceases to grow and fades to a
dull brown and the plant looks to have recovered completely. However, the
disease is perpetuated by dormant spores hidden mainly under the bulbs outer
tunic which become active again during the next cool period.

It appears resistant to just about every fungicide I've tried whilst in the
bright-red active stage but better control can be had when the bulbs are in
full growth (summer). Try peeling back and destroying (burn) the dry outer
tunic and spraying the whole plant with systemic fungicide. Follow this with
drenching the compost similarly. Afterwards, you will need to spray every
7-10 days until the plant becomes dormant (after which, of course, systemics
won't work). Finally, give the now dormant bulbs a drench of protectant
(contact) fungicide before drying-off for their rest period (copper-based
fungicides are good for this).

This fungus nearly always arrives via newly acquired bulbs. A good plan is to
give all new bulbs a one-hour bath in a fungicide to which a drop of
washing-up liquid is added to aid penetration.

Now....... If anyone has an easier method?

Best wishes.
Den Wilson
Isle of Wight
Stagonospora curtisii is best controlled in outdoor ag situations (such
as garlic) with a chemical known as Dyrene.  0ther common fungicides such as
mancozeb, benlate, Bravo, etc., can be used but some university tests done
here in California some years ago on narcissus showed Dyrene to be the best
control in the field.
     A hobbyist in Florida told me he was successful in controlling it on
hippeastrum and narcissus with Physan 20, also known as Triple Action 20.

Best wishes,

Bill the Bulb Baron

In response to this someone else said that many of the fungicides mentioned 
by Bill (dyrene, benlate) were no longer available. As someone who hates to 
use heavy duty chemicals I am wondering if anyone in this group has used 
Triple Action 20. I have used it for other things like cleaning areas in my 
greenhouse with some success.

Does anyone know whether Nerines can get this? I have one this year that is 
outside being rained on that has red on the leaves and I don't remember 
this in year's past. If it has it when should it be treated? It will be 
going dormant in summer.

Mary Sue

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