Graham,
I see that you have posted photographs on this site of galls on Alexanders.
On a walk recently my wife and I found the below "galls" on the Alexanders at Skinners Wall, Manningtree.

The underside of a leaf.

The top of a leaf

Close up of the underside of a gall
On top of the leaf they were green smooth, rounded and greasy in appearance. On the underside they were transparent with yellow cups inside. Each cup had a yellow ball in its mouth. They appeared to progress to a flattened wound on the top of the leaf while below the yellow cups appeared to have emptied and were turning a shade of brown.
Not knowing what we had found, I 'Googled' it and came up with a result, the fungus, Alexanders Rust Fungus (Puccinia smyrnii)
A question remains, how common is this fungus. NBN Gateway maps show it prevalent on the West Coast, North Norfolk and Suffolk, but none in Essex.
Is this a new phenomena in Essex or is a case of under recording.
By the way thanks for your excellent forum articles, not my area generally, but none the less a very interesting read.
On a walk recently my wife and I found the below "galls" on the Alexanders at Skinners Wall, Manningtree.

The underside of a leaf.

The top of a leaf

Close up of the underside of a gall
On top of the leaf they were green smooth, rounded and greasy in appearance. On the underside they were transparent with yellow cups inside. Each cup had a yellow ball in its mouth. They appeared to progress to a flattened wound on the top of the leaf while below the yellow cups appeared to have emptied and were turning a shade of brown.
Not knowing what we had found, I 'Googled' it and came up with a result, the fungus, Alexanders Rust Fungus (Puccinia smyrnii)
A question remains, how common is this fungus. NBN Gateway maps show it prevalent on the West Coast, North Norfolk and Suffolk, but none in Essex.
Is this a new phenomena in Essex or is a case of under recording.
By the way thanks for your excellent forum articles, not my area generally, but none the less a very interesting read.