Twayblade mildew

Plant diseases
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markwilson
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Twayblade mildew

Post by markwilson » Thu May 16, 2019 12:10 pm

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Does anyone know anything about what I think is a mildew on Twayblade Listera (Neottia) ovata Could find nothing in Bladmineerders or the new Welsh list mentioned in this site. From West Somerset

o.ellingham
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Re: Twayblade mildew

Post by o.ellingham » Thu May 23, 2019 10:15 am

Hi :) ,
That is an interesting find, especially because there don't seem to be any records of PM on this host plant (in the taxonomic manual of erysiphales, nor in the USDA fungus-host database).

It is difficult to say for sure, but I think it most likely to be a disruption of the epidermal layer of the plant that has produced this powdery white appearance.

In future, you can give the surface a tough rub to see if the white comes off easily, if so then unlikely to be PM.

Microscopy would be the most conclusive way to investigate. Feel free to send any interesting samples to myself at Kew in future :ugeek: .

Happy hunting, Oli

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Chris Yeates
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Re: Twayblade mildew

Post by Chris Yeates » Thu May 23, 2019 6:38 pm

o.ellingham wrote:
Thu May 23, 2019 10:15 am
It is difficult to say for sure, but I think it most likely to be a disruption of the epidermal layer of the plant that has produced this powdery white appearance.
My thoughts exactly - the pattern of "infection" just doesn't look quite right.

Chris
"You must know it's right, the spore is on the wind tonight"
Steely Dan - "Rose Darling"

markwilson
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Re: Twayblade mildew

Post by markwilson » Wed Jun 05, 2019 3:49 pm

Drs Roger Cook and Oliver Ellingham have looked at specimens of twayblade leaf and have not been able to find positive signs of mildew. Thanks to them both. Mark Wilson

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