Mildew or another fungus on Cherry Laurel?

Hi James

a bit less straightforward this one. For a long time powdery mildews on Prunus were referable to Podosphaera tridactyla, with sparse mycelium and frequent chasmothecia (those globose ascospore bearing bodies you can see on that ASCOfrance link I sent). Here we have the opposite case with abundant fluffy mycelial growth, accompanied – as you correctly point out – by distortion of the leaf. This is almost certainly

Podosphaera pannosa (Sphaerotheca in older books). This is a species commonly found on roses – in the wild particularly in my experience on Rosa arvensis – which has recently ‘jumped’ to Prunus laurocerasus in this country.

You can follow some of the saga here: http://www.fieldmycology.net/FRDBI/FRDBIrecord.asp?strAssoc=Prunus+laurocerasus&strName=Podosphaera+pannosa” class=”bbcode_url”>http://www.fieldmycology.net/FRDBI/FRDBIrecord.asp?strAssoc=Prunus+laurocerasus&strName=Podosphaera+pannosa

cheers

Chris

Oh so Mildews are not so simple – just like Rusts! I’m going to stick with my attempts to id Rusts for the moment!

There are very few problem areas with rusts, smuts and mildews; as long as you know those problem areas it’s pretty straightforward. In this case the problem I was highlighting was that in this rare instance a newer species has appeared than is mentioned in the books most people will be using.

Some years ago Bruce Ing produced a series of papers on powdery mildews in the Mycologist – I’ll join up some scans and make it available as a PDF for UK Fungi people . . . .

Chris

Plus your microscope for some!