I planted a David Austin Gertrude Jekyll rose this spring. After closely inspecting the first and second flushes, it is clear I have rose midge stunting the new growth and bud formation. The rose gets about 6 hours of sun from morning to midday, and is in a large raised planter made of cedar wood. Compost and mulch are added in the spring and autumn. I am located in south Etobicoke. So for the two other roses in the yard have not been affected.
Do you have recommendations for a treatment plan? I understand this pest is notoriously difficult to get rid of. I have sprayed Safers Rose & Flower Insecticide on it twice so far.
Thanks for the help.
Thank you for contacting Toronto Master Gardeners with your enquiry.
Very happy to read that your other two roses have not been affected so far. You will definitely need to keep monitoring them, however, while your attention is focused on treating the affected rose bush.
Caused by a small gall midge fly, commonly known as the rose midge (Dasineura rhodophaga), rose midge disease is a plant pest infestation affecting roses. Adult midges lay their eggs on new growth, resulting in larvae that feed on the young and tender parts of the rose plant, causing damage and deformation. This hyperlink will take you to a very informative article that discusses the symptoms, conditions, and treatment of rose midge disease.
An Integrated Pest Management Plan (IPM) is perhaps the best way to prevent and treat rose midge infestations. The following resources are also exceptionally informative, and will help you formulate the best IPM for your particular situation:
1. For an overview of rose midge description, biology and life cycle, please see here.
2. And this link will take you to the Indianapolis Rose Society where they discuss some effective control measures.
3. And finally, Oregon State University also has a suggestion for a cultural control measure specifically related to mulching.
Hoping some of this information will help you keep your roses free of pests!