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Brown spots and rot on Iris germanica

LoxleyLoxley Posts: 3,663
Brown spots and rot on Iris germanica... are the plants salvageable or is it best to get rid?
(We have about 20 of them on a site we're working on, and the landsape contractor has had them with the other plants under a sprinkler... obviously they have not enjoyed it... all have brown spotted and yellowing leaves to some extent, some have slimy gunk and necrotic areas around the leaf bases).... There are other irises on site elsewhere, which are still quite healthy - would not like to cross-infect them

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  • Lena_vs_DeerLena_vs_Deer Seattle WA, USAPosts: 61
    Hard to say without photos, but they should be salvageable in theory.  Depends on how hands on you want to be with it :)

    I once had some necrotic areas on rhizomes that looked like they were caused by moisture and infection. Slimy, too. Whole fans gradually would get pale and then die, Similar to what you described. But after digging it out a little around the clump I found that it was just eaten from under the bottom of the clump by earwigs and snails. It had a damps spot under the main rhizome. 

    So what you could try is to loosen soil around it for now, see if there's any damage visible below the top level. Trim all the sick parts, but keep healthy bits till they die out naturally. Lift the whole clump in fall and separate all good rhizome chunks and dispose of "mother" part. If there's any infection or spores, it is very likely to overwinter in old parts. You can add more drainage to old spot and sort of mosaic healthy rhizome bits back where the clump was.

    I have at least 7 different varieties of iris adjacent to lawn and they get watered with it. Plus 40 inches of rain annually outside of summer season. Sprinkler in general is not a problem as long as it has drainage appropriate for particular spot.  Also depending and what plant it's companioned with, maybe companion is crowding it in terms of ventilation? and just gives less chance for it to dry out.
  • LoxleyLoxley Posts: 3,663
    Thanks! These are sat in pots waiting to be planted. I can trim them up before they go in the ground, not sure what the client's going to say about it though (he doesn't understand gardening). It's a pity, they are flowering quite impressively at the moment.

    It's not easy planting irises in flower though - they are easily destabilised!

    We had the irises delivered about three or four weeks ago and have planted some of the very dark ones already, which seem to have been OK. (They were from a different nursery). 
  • Lena_vs_DeerLena_vs_Deer Seattle WA, USAPosts: 61
    Yeah, it's not gonna look good for sure if it's for someone's garden, especially if they don't have understanding of gardening and just want something pretty now. Can be a very upsetting thing to see put in a garden.

    Maybe then it would be better get rid of it after all. Perhaps nurse it meanwhile for some other order down the line. If client spots the sickly look, they may not want it in their garden either way, recovery or not. 
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