On 11/06/20 15:32, Nick Maclaren wrote:
In article ,
Jeff Layman wrote:
On 30/05/20 20:19, Jeff Layman wrote:
I have a 3-years old Eryngium x zabelii 'Big Blue' which has collapsed.
I noticed a couple of days ago that one of the flowering stems (not yet
in flower) had turned back on itself as though it was suffering from
drought. I gave it some extra water, but it didn't help. An hour ago I
had another look and barely any of the plant is upright. Other plants
nearby are unaffected (including E. bourgatii and E. variifolium).

If it doesn't recover I'll dig it up and have a look. It's the sort of
thing I associate with vine weevil, but according to various refs they
almost never touch eryngiums.

Anyone seen anything like this in their eryngiums?

Yesterday I tried to pull off a couple of dead leaves and the whole
plant came up. The root was rotten and smelt of bad fungal decay. I've
no idea what could cause this. It certainly hadn't died of overwatering!

Almost anything, unfortunately. The fungal decay could be secondary.

I am getting a bit concerned that my garden soil may have Phytophthora
in more than one place. Last year I lost a /Grevillea rosmarinifolia/
which died within a period of one or two weeks from being apparently
healthy. This was a 2m x 2m plant I had had for around 6 years. Now I
have an Eryngium, which normally nothing touches, dying within a short
period. Both are susceptible to Phytophthora, the Grevillea very much
so, the Eryngium has some susceptibility. They are at least 10m apart.

According to the RHS, Phytophthora is becoming more common (climate
change?) and is probably the cause of more plant deaths than originally
thought. I think I'll get some Potassium Phosphite solution and water
the soil where those plants died.

--

Jeff