Blisters on daffodil leaves

WillowBark

Does anyone know what may have caused these blisters on the leaves of one of my daffodils? Is it frost damage? It's only the one plant that's affected, all the others seem fine. Thanks.

Uff

How strange. Has there been a frost as the leaves were emerging WillowBark? I'm only guessing because I've never seen anything like that before. Might it be either a fungal or virus problem? I know that some bulbs, especially the onion family can have these problems. 
I await with interest to hear from someone who knows what it is. 

Pete.8

It looks a bit like some form of oedema, but I've never seen it on a daff before.
Is there a depression on the reverse of the leaf where the blisters are or is it more like a lump?

WillowBark

@Pete.8 There's no lump on the reverse, a very slight depression or ripple in the surface that would correspond with the blister above, but not nearly so obvious an anomaly as what can be seen on the top side. When I bent one of the leaves back to take a look at the underside, the leaf started snapping at a junction where the blister met normal leaf. That end of the garden can get quite waterlogged and muddy at this time of year, so I guess that might correlate with oedema?

WillowBark

@Uff I think it was one of the earlier daffs to start emerging, and we have had one or two frosts during that time, I think, so it could be that. I did wonder about viruses etc., but nothing I could find with a preliminary search online seemed to bring up quite the same symptom. It's also near to a bit of the garden that has high footfall, so I wondered if it had been damaged that way somehow, but it somehow seems too weird a pattern for that!

Pete.8

Strange..
As the leaves come from the bulb, I wonder if there's been some damage to that before the leaves appeared above ground.
So the damage was done to the leaves whilst still in the bulb.