There were only two things that were different around that rose in the last couple of years versus the rest of its life:
1) we took out a huge (4 ft high by 3 ft wide in all directions) old jade plant that had been growing next to it (the jade plant was there before the rose) last Spring when it suddenly collapsed, and on examination, the base of it was all rotted.
2) I grew a clematis up a small trellis right next to the rose, and the clematis was touching the rose, but only in the first 6 feet, where there were hardly any leaves or anything. The clematis had powdery mildew most of the time.

Could this be canker? It is possible that some of the canes had marks on them - my DH was the one who got up on the ladder to prune it, and he is not very observant vis a vis plants. I did look when it started to die, but by then about 1/3rd of it was dead, so perhaps any marks were not visible anymore.

There is a tiny polyantha which has been growing about 2 feet away from the base of the dead rose since last Spring, and it still looks great.

We pruned the clematis back to about 2 feet yesterday, and cut the dead rose down, and tomorrow my DH is going to dig up the stump. My plan is to just add a bunch of compost & mulch to that area, and let it sit until next Spring, when I want to plant a Reve d'OR there.

Question - is there anything else I should be doing other than spraying the little polyantha and the remaining clematis with fungicide? Is there anything I could put in the soil?

It was almost frightening to watch the speed with which the old GS died - any thoughts or suggestions would be very welcome. Thanks -

Jackie

Did you get heavy rain last winter? Perhaps a pathogen in the soil got enough moisture to go after the root system.

Very worthwhile to investigate the rose roots for pathogens, rot. Sniff the soil after removal--sour smell?

Really odd. Sorry for your loss. Must have been a beauty!

It would probably take molecular scientists who are working on the Jade plants (if there are any) to try to see if it's disease is graft transmissable.

But the timing of the two deaths may be a clue,nonetheless.

The only other thing like that I've seen was our Reine des Violettes. A virused plant from ROY&T, it was planted in 1987, and grew happily (not even showing signs of the virus we knew must logically be there) until the spring of 2007.

Then, it suddenly broke out in signs of virus from top to bottom, gave us one last flush of bloom, and died.

Jeri

So, we dug up the soil, and replaced it with new soil, and I went to look for some sort of fungicide drench to pour over the new soil and the rest of the bed. Then I plan to leave it until next Spring.

I went to my nursery (it is the one described at the Sac Cemetery rose symposium as "the oldest continuously operating nursery in California" - the West End Nursery in San Rafael). The owner is very knowledgeable about many things, although they do not specialize in roses. He recommended "AGRI-FOS, which is a systemic fungicide that can be used as a spray or a drench, and kills many different fungus diseases. You can also use it to soak new plant roots in before planting. He said that anything else that might work is illegal in CA, as they have made most of the chemicals illegal. He laughed and said that they cannot make this one illegal, as it is the only thing that works to prevent sudden oak death!

So, we got some and drenched the area. I disconnected the irrigation, which is turned off now anyway. We will see what happens to the little polyantha rose - if it is still OK next Spring I am planning on planting a Reve d"or to replace the GS.

Jackie

Without knowing exactly what fungus was involved, I sort of THOUGHT that some sort or rot or fungus had gotten through the root system.

Your solution makes sense to me.

Jeri

In another area, I had carved out a little grove to be surrou nded by largerer shrubs and filled with the most fragrant roses and a pretty little bench, all getting afternoon shade from a lovely maple. But none of the roses thrived. Turns out, maple roots are shallow and strangling. Now I pay pay attention to what's happening underground.
.

Jackie

Verticillium is one exception, that one likes alternating wet/dry soil conditions. Main symptom of verticillium is one branch dying completely, then another. Maples are very susceptible, don't recall losing any roses to it though.

My guess from your description would be armillaria root rot, what you all in California call oak root fungus. Adding irrigation to plants that didn't have it before is one sure way to kill them with armillaria! but it doesn't have gray mushrooms. Honey-colored mushrooms around the base of the plant, but it does have blackish lumps and strings underground. What you saw was probably something else, there's a lot of things living down there underground. Taking advantage of the dead roots.

Best defense against armillaria and any other root rot is to manage irrigation and add compost. That way you don't get the soil moisture conditions that are conducive to infection, and you have a thriving microbial community to keep any one species from growing out of control.

Nothing you can spray on the plant tops will work on root rots. Soil drenches are iffy too, frankly, it's hard to get just the right amount spread through the soil, and it kills off the beneficial soil microbes, and the pathogens come back.

The jade plant could have died from armillaria as well. Lots of plants are susceptible to in (including oaks, hence the common name!) and like most root rotting pathogens, it's everywhere at small populations, just waiting for the right soil moisture conditions and the right host plant. And it will spread from plant to unrelated plant underground, growing from one infected root system to the next uninfected root system. That's the black strings you might see.