Growing a collection of 90 kinds of roses, our rose growers understand how to grow healthy roses. This week, Natorp’s Rose experts are answering your questions on caring for Roses.
Rose Garden Questions
“My rose’s leaves are being destroyed! They are being eaten but I can’t find anything eating them. What can I do?”
I’ll bet you’re experiencing rose slugs, which are not a slug at all, but the larvae of a sawfly. They look like a thin, small, lime green caterpillar feeding on the undersides of the leaves. There can be multiple generations, so you’ll need to stick with the controls. Applying a systemic insecticide at the base of the plant is your first step. For insecticides, Insecticidal soaps or Horticultural oils sprayed on the undersides of the leaves helps. Just a strong stream of water and hosing them off can help. Good thing is, those rose leaves may look bad, but for the most part, the roses keep flowering. By the way, after the first good flush of rose flowers, deadhead and feed your roses.
“How do I treat rose rosette?”
A lot of research is being done now to find a cure for the rose rosette, or find resistant roses! Make sure it’s rose rosette; other issues look-alike including plain old maroon red growth. If it is rosette, do not wait to pull them. If you do, you’re allowing the mites to spread and infect other roses. Pull and pitch. Research is showing you cannot spread the mites by clothing or tools, nor can you spread this virus by the tools you’re pruning with. And in most cases, if you pull out the infected roses and get most of the roots, there is no reason why you can’t replant roses there, other than you know the mites are in the area and can re-infect the new roses. But make sure that’s what you have before you start pulling.
“How do I stop the holes in my rose?”
Have you noticed green caterpillar-like critters on the bottom of the leaves? These are the normal culprits.
There are a couple of ways to treat them:
- Apply imidacloprid (soil drench) as well as foliar sprays of insecticidal soaps, hort oils, etc. on the undersides of the leaves
- Hose off with a steady stream of water
You want to be vigilant because there can be multiple generations.
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