How to treat fungus on Rose?

laura5

Hi, I’ve got some sort of white disease at the bottom of my rose trunk and the bark has gone. I think it is because it wasn’t getting enough airflow last winter/spring (we had marigolds growing in the garden bed at the bottom of the roses). I’m assuming lack of airflow is the cause as it’s only the bottom foot of the trunk which is affected. 

The rose plant doesn’t seem as strong anymore, but not terribly affected. 

Is it a fungal infection or something else?  Do you think due to lack of airflow or a different cause? 

Can you pls advise treatment?  Is there a natural method of treating rather than chemical? 

thankyou! 
- Laura 

JacobZ

Hi @laura5,

A warm welcome to the Bunnings Workshop community, it is fantastic to have you join us.

It looks like your roses have powdery mildew growing on their trunk. 

Powdery mildew is a fungal disease, appearing as a white, powdery coating on leaves, stems, buds, and sometimes even the trunk.

One of the most common causes of powdery mildew on roses is poor air circulation. When roses are planted too closely together or positioned against a fence or wall, airflow is restricted, creating an ideal environment for mildew to grow. Similarly, watering roses from above, particularly in the evening, can increase humidity around the plant, further encouraging fungal growth.

The first step, which you've already taken by removing the marigolds, is to allow better airflow around the roses.

Now you can use OCP 750ml Ready To Use Eco-Fungicide to treat the remaining mildew and prevent its spread. The active constituent in this product is potassium bicarbonate, which, by creating an alkaline environment on plant surfaces, prevents fungal spores from germinating and spreading. It is considered a safe, organic-friendly alternative to chemical fungicides. Apply this product every 7-10 days, ensuring the mildew is sufficiently coated until you are confident it is gone.

Let me know what you think, and if you have further questions, please don't hesitate to ask.

Jacob