Care of NoKnock Rosebushes

Asked June 11, 2019, 1:01 PM EDT

Our bushes are few years old, previously healthy. First time This year all the leaves are covered with holes. They are blooming. Your recommendations for treatment please? Thank you

Baltimore County Maryland

1 Response

Sounds like rose slug damage. This is a common problem of knockout roses.
The holes on the leaves are caused by rose slug sawfly larvae. There are several types and may 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