How to treat powdery mildew on rose stems?

GlendaJoy

We Moved to an apartment with a balcony facing east so not all day sun. We have been here a year and I sprayed originally a couple of times but it has now got really bad. Is it too far gone? I have pruned off the dead wood. Can I hand wipe it off with something like metho?

I canmove it to another garden somewhere else. Will it infect anything else?

MitchellMc

Welcome to the Bunnings Workshop community @GlendaJoy . It’s wonderful to have you with us and many thanks for your question on roses.

Unfortunately, the photo isn't quite clear enough for me to positively identify what is affecting the rose. Powdery mildew commonly appears most noticeably on the leaves, buds and young growth, although it can also affect stems. It is typically a white to light-grey powdery coating, so the colour you've shown wouldn't necessarily rule it out.

However, because there appears to be quite a substantial coating over the woody stems, I'd also be wondering whether you're dealing with something such as scale insects, particularly a white scale, rather than powdery mildew. If you could take a couple of close-up photos of the affected stems and any affected leaves, that would help us identify it.

I wouldn't recommend wiping the stems with methylated spirits at this stage. It could damage the plant tissue, and without knowing what we're treating, there's a risk of doing more harm than good.

If it is powdery mildew, it certainly doesn't mean the rose is beyond saving. Remove badly affected growth, dispose of it rather than composting it, and treat the remaining plant with a fungicide labelled for powdery mildew on roses. Improving airflow and giving the rose as much sunlight as your balcony allows will also help. When watering, concentrate the water around the soil rather than wetting the foliage.

Powdery mildew produces spores that can spread to other susceptible plants, so I wouldn't move an actively infected rose into another garden until you've identified and brought the problem under control. Also, clean your secateurs after pruning affected material.

Here's a helpful guide: How to maintain healthy roses.

Please share those close-up photos when you can, and we'll have another look.

Mitchell