When roses are accidentally hit with Zero or Roundup, they usually show the
effects in the parts less affected, by turning the leaves a little stumpy
and curled. If there had been spot spraying of a herbicide you would expect
to find this on the branches adjacent to the ones dying back.
It could be a soil fungus such as armillaria, which affects any root coming
into contact with the fungus in the soil (usually on old affected roots of
trees, shrubs or other plants long since dead). This would account for the
partial die back. Have you noticed any toadstools growing in tight clusters,
and sandy in colour? They are seasonal, according to area - basically
whenever the mushroom season is for you.
I hope this helps.
Cheers,
Alwynne
"Andrew G" wrote in message
...
Hi everyone.

At work our ground cover roses have developed a problem.

About 4 weeks ago we noticed some slight discolouration in the foliage,
and
some of it was concentrated in patches.
We fertilised them with a liquid feed. It didn't make any difference.
2 weeks ago there were totally dead patches forming in some of the roses.
Best was to describe it would imagine if the branch had been snapped off
toward the base, and that whole branch died.

The dead leaves showed no signs of insect damage or fungal probs. Other
"good" leaves are ok, but about a week ago we noticed thrips. Treated them
for that, and also treated them for some very slight black spot.

Today we noticed another one with discolouring patch. There are probably
others that have developed it in the past week, but there are so many, and
this particular one we noticed cos we always walk past it.

All up there is probably about 80 roses. Not all of them have the problem,
just most. I know of a couple of perfectly good ones, amongst the others.

Moisture seems ok, if anything possibly a little too dry, but that doesn't
explain just dead patches.
They have been established for about 2 or 3 years, and it's the first time
it's happened. Another way to describe it, is if someone had sprayed just
small patches with a contact only herbicide.

Anyone with any ideas, or have seen this problem before?

My only guess is that some of the branches that are perhaps laying on the
ground have been covered with some fallen leaves and flowers from the
rose,
then the matter has rotted down on the branch and killed it. Kinda like
putting mulch around a tree hard up against the trunk can kill it.

Thanks for any help

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