In message , Nick Maclaren
writes

In article ,
Stewart Robert Hinsley writes:
|
| Some rusts have alternate hosts - if I recall correctly one rust attacks
| wheat and barberry.

It does. Looking at Collins indicates that most have alternate hosts,
and there aren't many rusts that affect a wide range of plants. I was
wrong there.

| I'd be surprised if a rust of Euphorbia infected other genera.

Try pea rust. They are the alternate host. And, given that 'pea'
includes a fairly wide range of legumes, ....

Yes. I suppose I should have caveated the possibility of an alternative
host.

Regards,
Nick Maclaren.

--
Stewart Robert Hinsley