How To Deal With White Spots on Knockout Rose Leaves

So we’ve got a question from Ed. He says, ‘I have several knockout roses, and I’m already seeing white spots and holes on the leaves. I have sprayed a three-in-one insect disease and mite control, have not seen any improvement as of yet. Any suggestions would be appreciated.’

Okay. So, Ed, I’ve used that same spray on my knockout roses at home, and you have to apply it more than once. So you apply it seven days later, you apply it again seven days later, you apply it again, at least three applications.

So to prevent that pain, this year I went to a granular, which is called Tree and Shrub Protect, and I put it right into the soil. The plant, every time it rains, which we’ve had plenty of, that chemical goes into the soil, the plant absorbs it, and it runs inside the sap system.

It’s also, I believe, a little safer for the bees than the topical sprays as well. And I’m at work a lot, so by the time I get home, sometimes they get ahead of me. Now, those leaves are not going to repair themselves. I have a lot of people who think the leaf itself will regrow and fill that tissue, and it does not do that. So you want to make sure that you get it down early and stay ahead of it. And this year, I’m using that granular, I will let you know if it works better than the spray. Just because by the time I get home from work, I realize that they got into it two days ago, and now I have holes in my leaves. I’m trying to use that as a preventative this year.

You can take the leaves off or you can leave them on. It’s really up to you. If more than half of the leaf is damaged, I would take the leaf off because it’s going to continue to degrade. If it’s just a few small holes, you can leave it be for the time being. If it’s just a few, I usually recommend just leaving them on because it still, the leaves still have nutrients making food.

Fertilize it really heavily, that helps it recover and helps it naturally fend off a lot of issues it could have. And if we could get it to warm up a little bit, that will really help. That has a lot to do with why you’re not really seeing any, because there’s really not anything going on right now because everything’s just kind of at a hold. We should see an explosion of growth with all that heat that’s coming. That heat’s going to really help.

Questions? Email us at [email protected] or call one of our two locations: Portage (330-499-0101) or Everhard (330-492-1243).

Questions? Email us at [email protected] or call one of our two locations: Portage (330-499-0101) or Everhard (330-492-1243).