Asked on Jun 17, 2019

Is there an organic fix for knockout roses covered with holes?

by Mimi

Nothing else surrounded them are effected. Is there an organic fix? See pic:

  10 answers
  • Joy30150932 Joy30150932 on Jun 17, 2019

    Try spraying them with a mix of one part hand liquid hand soap and 40 parts water and spray the leaves. Do this in the shade and give it 15 minutes to work. Then spray off again with the hose. Repeat if necessary.

  • Robyn Garner Robyn Garner on Jun 17, 2019

    "The rose slug is actually not a slug. It is larvae of sawflies, which lay their eggs on the underside of rose leaves. These annoying pests feed on the leaves of Knock Out roses, leaving holes in them. In large infestations, rose slugs can lead to loss of vigor, and wilting and leaf dropping. In extreme circumstances, rose slugs can defoliate entire shrubs. Spraying the infested shrub with ready-to-use insecticidal soap weekly or biweekly helps control rose slugs. Be sure to cover the entire plant with the soap, including the top and underside of the foliage."

    "it's important to positively identify the pest involved. Rose slugs range in color from light green to black and look similar to small slugs or caterpillars. Like caterpillars, these larvae have legs and leglike protuberances."

    "Treating them with garden chemicals requires catching them in the act of eating your rose leaves, though. Hosing them off your Double Knock Out rose may be all you need to do, but for heavy infestations, consider using insecticidal soap or spinosad."

     Caterpillars can be controlled by spraying Bt, a natural insecticide.

  • Lynn Sorrell Lynn Sorrell on Jun 17, 2019

    Neem oil... Weekly use of a neem oil spray at a normal concentration (0.5% - 2%) will not hurt honey bees at all. You can also rest assured that while neem hurts aphids, whiteflys and the like, it does not harm ladybugs and other predators that eat the aphids, or the tiny wasps that are parasites on many pests. Cutter bees will make half-moon shaped notches in the leaves of some rosebushes. With cutter bee damage, I just leave them alone and treat it like a badge of honor. Cutter bees do a lot of good and having them choose some of my roses to make their nesting materials with is a small price to pay. While they can do considerable damage to many leaves, the rose will grow back, just keep it well watered and put some Super Thrive in the water to help them deal with the stress and shock. Some beetles like to punch holes in the foliage of rosebushes to suck out the juices as a means of nourishment. The same is true of some rose slugs (sawfly larvae), but they usually will not stop at a few holes. Instead, these pests end up devouring or skeletonizing the entire plant. Spraying the rosebushes with a good insecticide that has the culprit listed will help to gain control of the situation. The rose leaves with damage to them may be removed if desired, but again, affected rosebushes will usually bring forth new foliage that will perform better. Rose chafers can also cause this type of damage but will usually attack the blooms as well. Caterpillars are another common pest of roses. Their damage usually presents as numerous irregular areas near the center of the leaves, or entire leaves eaten. Most of these can be hand picked off and dropped into a bucket of water. Likewise, the use of Bacillus thuringiensis is another nontoxic approach for them.(this is Mosquito Bits/Dunks)

    • Ellis Ellis on Jun 18, 2019

      Yes, a very fine nursery I frequent recommends Neem oil for insect problems. I've used it myself, and it works. I always start with Neem oil, and only move on to more powerful remedies if absolutely necessary.

  • Maricela Ramirez Maricela Ramirez on Jun 18, 2019

    I recommend to use dish soap w/ out any perfumes and water. Spray over the plant and it works 100% and I recommend the dish soap w/ out perfume so it won’t damage the plants. And this I use it in all my plants

    • See 1 previous
    • Nancy Weinberg Nancy Weinberg on Jun 21, 2019

      I have been using dish soap in the garden and have never had the problem you describe.

  • Maricela Ramirez Maricela Ramirez on Jun 18, 2019

    Thank you for this important information, for now on I won’t use it anymore at all.

  • I use soap and water and I've never had an issue with it damaging the plants. I use it inside and outside. I would try it on the roses as well, but as recommended above, I would use a very gentle, free of perfumes and dyes soap.

  • Annie Annie on Jun 16, 2021

    Try the Neem oil that should work. It's definitly bugs at work here

  • Chloe Crabtree Chloe Crabtree on Jun 16, 2021

    I believe this is the larvae of sawflies causing these holes. You can try a stiff stream of water on the leaves. Once the larvae are dislodged, they will not be able to reattach to the leaves. If that does not work, you can use Neem oil on your roses.

  • Maura White Maura White on Jun 17, 2021

    I used soapy water (seventh generation dish soap watered down) on my roses and that killed whatever was eating mine.