In message , Sandy
writes
Stewart Robert Hinsley wrote:
Some rusts have wide host ranges; others have narrow host ranges.
Hollyhook rust, for example, attacks a variety of mallows with
various degrees of severity. Hollyhocks, common mallow and it's near
relatives, and musk mallows are the worse sufferers. Shrubby
Lavateras aren't much affected.
Some rusts have alternate hosts - if I recall correctly one rust
attacks wheat and barberry.
I'd be surprised if a rust of Euphorbia infected other genera.

Talking of rust, I seem to be having a major problem with it this year,
so far affecting peas (mange tout) garlic, hollyhocks and rhubarb.

Is it transferable amongst these crops/plants, and what causes it, and
is there anything I can do to prevent/treat it?


I'd expect that you have four different rusts there.

Pea rust = Uromyces fabae
Garlic rust = Puccinia allii syn Puccinia porri
Hollyhock rust = Puccinia malvacearum
Rhubarb rust = Puccinia rhei-undulate
--
Stewart Robert Hinsley