Rose problem

Asked May 17, 2019, 2:31 PM EDT

It looks to be a virus on 1 rose and another insect damage on the other. Please help. Thank you,

Anne Arundel County Maryland shrubs roses rose slug cercospora

1 Response

The holes on the leaves are caused by rose slug sawfly larvae. There are several types and they can be active through the fall. Look on the undersides of the leaves for the young larvae. If the infestation is light, pick off and destroy the larvae by hand. To control heavy infestations, use horticultural oil or spray with spinosad. Target the undersides of the leaves. See our website for more information
https://extension.umd.edu/hgic/rose-slugs-shrubs

The spots on the foliage looks like a fungal disease called cercospora. Remove dead and diseased leaves that have fallen by raking, and use mulch to create a physical barrier between the plant and fungal spores on the ground. Drip irrigation or watering at the base of the plants keeps the foliage dry and less susceptible to fungal infection. Practice good sanitation. If only one branch is affected, you can prune. However there needs to enough foliage on the plant so it can continue photosynthesis.

Monitor the plant and you will have to decide if you want to spray fungicides. Fungicide sprays are preventatives not curatives. It protects new growth only. Follow label directions if you want to use it. Also, you can look for disease resistant varieties of roses.

Marian