Wordless Wednesday–What’s Wrong With My Rose Leaves?

damaged rose leaves with larva

Every year about this time (actually, slightly earlier) my neighbors know that I am an organic gardener because although I may have lovely rose blooms, my leaves look like those above.

Why? First of all, I’m not growing all Knockout roses, which don’t seem to get bothered.

But that’s not the answer you’re really looking for. If you look at the second leaflet on the lower right, you can barely see a tiny caterpillar-like insect. I have better photos from my post on the topic last year.

This is the larva of something called the rose sawfly.

Since it’s not a caterpillar, bt (bacillus thuringencis) doesn’t work.

The non-organic folks can use systemics to solve for this–but many of the rose systemics have the same neonicontinoids that may be implicated in bee deaths. So if you are non-organic, please reconsider this.

On occasion, and this year was one of those, I sprayed an OMRI certified herbal oil for this–just because the population seemed inordinately high. Insecticidal soap will also work–but again, spray at sunset so as to disturb as few beneficials as possible. Remember, these “good organics” don’t discriminate between good bugs and bad bugs–they just kill everything they land on–rose sawfly larva, spiders, bees–so try to spray when as few “good bugs” are around as possible.

I also had a caterpillar–a genuine one–eating my rose buds. That I really didn’t want. So I sprayed–at sunset, on an extremely cool day, when it was least likely that any beneficials might be around.

This is probably the first time I’ve sprayed the roses in 6 or 8 years. I really hate to do it–but when I do it, I try to do it responsibly!

2 thoughts on “Wordless Wednesday–What’s Wrong With My Rose Leaves?

  1. Laura B June 19, 2013 / 9:41 pm

    I do grow knockout roses and I have these guys on them also. Knockouts arent immune. They are on all my roses. I was wondering why bt wasn’t working. Thanks for the info!

    • gardendaze June 20, 2013 / 8:38 am

      Thanks for reading and commenting. I’m sorry to hear that at least for you, the Knockouts haven’t been able to resist these nasty pests–but maybe I’ve been able to help a little in giving you a way to control them at least!

      One of the things I’ve noticed about the Knockouts (I’m on the road this summer, traveling with several roses in pots as I do a lecture called Easy Care roses) is that the leaves of the Knockout roses are thicker thank any of the others I’m traveling with (I’ve also got a David Austin with me, and an Oso Easy, A Fairy, a Flower Carpet and a Drift–so a good sample of roses). I was thinking that that was made them tougher.

      But I guess they are not always tougher. Read my post tomorrow on EarthKind roses–or research the Earthkind roses program yourself. The original Knockout rose is one of the Earthkind roses which again, is supposed to be pest-resistant–but that doesn’t make it fool-proof!

      Have a great day!


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