[Scribbler]

Got a patio rose in a bed by a paved area. Lots of new growth, but it has just developed some large red spots on the uppermost stems. Any thoughts re the cause? Disease? Could it have been frosted? All the low stems are fine, but top ones have these spots, which made me wonder about frost.

[gobs]

Could be anything, but I would be well tempted to cut them out as it's pruning time anyway, to well below the spots, disinfect tool and dispose carefully, not to be alarmist, but that's how canker can start. :shock:

Not worth the wait and see, won't be hurt by a prune.

[Scribbler]

This is what it looks like. Bit of a Munty shot, but gives you an idea.

[Trillium]

Those red spots could well be a fungal disease. They often start with poor air circulation or splash-back from rain or watering.

Prune off the infect areas and burn, disinfect your tools as Gobs suggests, and spray with neem oil as a preventative. If the plant is crowded in with other plants, you'll need to sort that as well.

[gobs]

This is what it looks like. Bit of a Munty shot, but gives you an idea.

I'm sticking by my answer. No frost them, I'd lose them quick. how far do they go down? You might need to lose entire stems there, possibly.

[Scribbler]

Had a tentative prune yesterday, but stopped when I realised that the blotches are all on the windward side of the stems, which is also south facing. The sheltered sides of the stems are all clear.

Very odd. Another rose close by is clear.

[Trillium]

Do you have any grapes growing nearby in the windward side of the roses? The spotting is common to grape plants.

[gobs]

Frost/cold/wind damage would be brown/black as if burnt, curled up leaves then with white blotchy patches on them.