Downy mildew on Guelder Rose

[Simon Horsnall]

Whilst out walking today I came across a Guelder Rose, Viburnum opulus. Noticing some yellowing of the leaves I flipped one over and noticed a greyish fuzz. I brought it home and under the dissecting microscope it appears to be downy mildew like in appearance and a portion under the compound microscope shows branched, what I assume to be sporangiophores but I can find no evidence of sporangia. On checking the ecoflora website, I cannot find a downy mildew associated with V. opulus.

Am I missing something obvious?

[Chris Yeates]

Hi
impossible to comment without any images I'm afraid. Are the hyphae septate?

Chris

[Simon Horsnall]

Thanks Chris. I've passed it on to a mycologist to have a look at. I will update when I get a response.

Simon