On Sun, 07 Aug 2011 15:41:01 +0100, Jeff Layman
wrote:

On 07/08/2011 13:31, Jake wrote:
On Sun, 7 Aug 2011 10:40:29 +0000 (UTC),
wrote:

Jake:
Having spent much of yesterday digging up all my impatiens, which have
succumbed to that fungus this year, and then buying up any remaining
decent bedding in the local garden centre to fill the more visible gaps,
it was heartening to read in Amateur Gardening today a prediction that
impatiens "could die out" within five years. Seems that T&M are
researching alternatives "in case".

I've got something in my head that I've read somewhere that other plants
are also possibly susceptible to this "downy mildew" fungus and
shouldn't be planted where impatiens have been affected. But I can't
remember where I read this and what plants were mentioned. Does this
ring a bell with anyone else?

Hi Jake

Could you describe what the fungus looks like?

I've got some impatiens, most of the flowers have gone (usually they last
till 1st frost), the few that are left the pink looks washed out with
white patches. The stems and leaves maybe look a bit yellow/brown but
mostly very light green.

Is this what you're seeing? Do I need to dig up everything& burn? To me
it looks more tattey than disaesed at the min - my natural reaction is to
leave them and see if more flowers come later.

Thanks!

Kate xxx

Hi Kate

Have a look at

http://apps.rhs.org.uk/advicesearch/...e.aspx?pid=205

That RHS page states "There are no fungicides available to amateur
gardeners for the control of this disease".

That's not entirely accurate. Amateurs cannot treat the disease once
the plants have it, but spraying with mancozeb (Dithane) can act as a
preventative to infection. See "3 Chemical control options" on the
final page at
http://www.stockbridgeonline.co.uk/w...ldew-guide.pdf

Whether or not you think it worth it to spray with Dithane is another
matter!

Thanks for this Jeff. It would be nice if the blasted fungus gave some
time to react but plants seem to succumb quickly and removing the
immediately affected plant doesn't stop the ones a foot (or six) away
going over the next day. The "white leaf underside" is really an
optional extra - there's no certainty you'll get it. By the time
something shows enough to be noticed it's too late.

Aside from anything else, an issue with using Dithane is that you
would be spraying the plants BEFORE there was any infection. If the
fungus is introduced (as I suspect is the case this year) then the
plants are already infected and Dithane will merely *possibly* control
spread.

Maybe next year I'll stop pulling up all the himalayan balsam - at
least it will fill all my beds, tubs, hanging baskets, gutters, gaps
between pavers and even, don't ask me how, a bit growing from a bit of
dirt at a branch junction in a crab apple tree.

Seriously, I wouldn't have had so many impatiens this year were it not
for the losses of perennials I suffered last winter. I only grew the
imps in bulk in case I needed to fill in gaps, as it turned out I did.
I'll replant the beds with something next spring, not being an autumn
planting fan. It'll be the imps in tubs and baskets that I really miss
next year.

Cheers
Jake
==============================================
Gardening at the dry end (east) of Swansea Bay
in between reading anything by JRR Tolkien.

www.rivendell.org.uk