infection on Anemone nemorosa?

[JPB]

I just found these strange deformations on stem and leaves. Is it an infection?

Hans

[mark smyth]

'Super Allenii' suffers from this some years or something similar and makes huge leaves

[annew]

Yes - it is 'Big Leaf'(!). To be safe, I would remove the affected rhizomes and dispose of them (not on your compost heap).

[JPB]

Thanks for your replies, I'll remove the infected parts. Still I do not know whether it is a recurring infection (I had it before and I removed the infected plants) or that it is triggered by environmental conditions....

[annew]

I am not sure anyone is sure what causes it.

[Tim Ingram]

My understanding is that this is caused by a mycoplasma (a bacterium lacking a cell wall that infects the phloem of plants) and causes virus-like symptoms - often dwarfing and yellowing. I don't know if these have been identified in Anemone nemorosa but they occur in Trillium causing deformation of the leaves and flowers, and all sorts of effects on other plants. It does seem to be a problem  (like viral infections) which can easily be spread by vegetative propagation, and Anemone nemorosa naturally spreads clonally with little increase from seed so may be more vulnerable than other plants? We've never found this to be a big problem in the garden (presumably infected plants or parts of rhizomes gradually die out) and the fact that a mycoplasma lacks a cell wall means that transmission is limited to vectors like aphids and leafhoppers that suck sap from the phloem, so it can't spread in the same way as fungi for example. It is certainly a problem for the nursery when a lot of these plants are grown but usually visible in the abnormal swelling of the rhizomes.

[arisaema]

Always thought it was fungal? It's quite common in the wild in southern Norway, big leaves that eventually seem to turn brown and release spores...

[Tim Ingram]

Sad to say (though we have never had this in the garden) Anemone nemorosa also gets a fungal disease (Dumontinia tuberosa), apparantly on, rather than in, the rhizomes which causes a black rot (ref: 'Pests and Diseases of Alpine Plants', Ellis, Entwistle and Walkey). This produces typical small cup-like 'mushrooms' at ground level (there is a good picture in the book). Leaf rusts are pretty common in plants too but they don't mention these in Anemone.

[Armin]

Hans,
could it be caused by cat piss?
I consider this as a possibility.

[ArdfearnAli]

I have it on some seasons on nemerosa flpl (vestal) and robinsoniana. It doesn't seem to affect nemerosa atrocoerulea, ranunculoides or the hybrid seemanii. I put it down to either a virus or perhaps climate. I think the best option as said is to remove infected rhizomes and hope it doesn't re occur. I tend to find it in pots but it seems to be ok in the garden.

Alasdair

[JPB]

Hans,
could it be caused by cat piss?
I consider this as a possibility.

Armin, I don't know. I do have cats but i keep my plants in pots...

[partisangardener]

Finally I found the culprit for this desease
It is a virus (Alloiophylly virus)
https://books.google.de/books?id=6KZkRmlQHN8C&pg=PA16&lpg=PA16&dq=deformed+leaf+Anemone+nemorosa&source=bl&ots=RfbAAjpCr2&sig=zorkVo6Qu72AIgA4F0cTUc-meSo&hl=de&sa=X&ved=0ahUKEwiRmIvTlcfaAhWliKYKHZaYBU4Q6AEIPTAC#v=onepage&q=deformed%20leaf%20Anemone%20nemorosa&f=false

[arisaema]

It still looks somewhat like rust to me, Ochropsora ariae and Tranzschelia anemones both infect A. nemorosa.

[partisangardener]

The Symptoms of both are very different. First one has smaller leafs.  In this case on the contrary.
The second one has the spore pimples underneath which are in the virus disease totally absent.

The description in my link fits perfectly to what I observe here the last decades, especially with Vestal. Abnormally big and somewhat deformed leafs, mostly without or rarely with deformed flowers.