Powdery Mildew On Roses

Question

I have researched the topic on the internet and learned that apart from the rose formulas which you can buy and spray on the rose to treat and control the infestation, I also learned about neem oil. I have three rambling or climbing Rose’s which I have planted over the last two years which I am trailing along a fence (Wedding Day). After a few sprays of formulated spray and also two sprays of neem oil which I had mixed with mild soap to mulsify the mixture the mildew was still present. I noticed one stem of the most mature rose had died and I decided it was time for a more direct treatment. I asked Google if I could apply, ‘Neat Neem Oil’ by way of using a small artists paint brush direct to the rose and if it would work or harm my Rose’s, I couldn’t find any answer on the internet hence writing to you with the results. I have checked for and damage to the stems or thorns of the rose and thankfully, all appears well and there is no sign of the mildew. I applied the Neem Oil seven days ago and hoping all is well? What is your opinion of my actions and do you have any help, advice or comments of my actions. Thank you Brian. South Wales, UK

Answer 1

You have to be really careful using Neem oil. If you use it while it is sunny out, it is almost guaranteed to burn your plants. Alternatively, you can use azadirachtan, which is the active ingredient in Neem oil.

https://www.gardeningknowhow.com/plant-problems/pests/pesticides/azadirachtin-vs-neem-oil.htm

As for now, I would cut away any heavily infected growth, and anything that is dead. Keep caring for it, as usual, and treat often if you know that the area will be humid, often.

Here are some articles that will help:

https://www.gardeningknowhow.com/plant-problems/pests/pesticides/azadirachtin-vs-neem-oil.htm

https://www.gardeningknowhow.com/ornamental/flowers/roses/roses-powdery-mildew.htm

https://www.gardeningknowhow.com/ornamental/flowers/roses