Knockout Roses – Treat Before Sawflies Attack

Q: How do I treat Knockout roses before the leaves are attacked by sawflies this spring?

A: You have reminded me that now’s the time to treat my own roses as a defense against the sawfly larvae that chew holes in the leaves. I’ll treat my hibiscus to protect against the same pest as well. I suppose organic control could be achieved by regular spraying with insecticidal soap when damage is first noticed but I prefer drenching with imidacloprid (Bayer Tree and Shrub, Bonide Systemic Granules, etc).

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