One of the biggest mistakes people make when they first buy a Knockout Rose is to think these roses are immune to everything.
It’s true they need less maintenance than traditional roses and have higher disease resistance. But they are not immune from health issues.
There are a lot of natural enemies your Knockout rose bush can face, such as an infestation of aphids (Macrosiphum rosae), Japanese beetles, spider mites, and other types of bugs.
Aphid infestation is a major concern for gardeners because they extract plant sap from plant tissues, hindering growth.
Aphids also produce honeydew while feeding, leading to sooty mold growth that darkens foliage and prohibits light from getting to the plant.
In the natural way of things, lacewings (green lacewings), larvae, ladybugs (also known as lady beetles), and parasitic wasps can help you with your aphids problem, but they can be the cause of new issues in your garden.
The good news is that the hardiness of these plants makes them less sensitive to some insecticidal products than regular roses.
What Is A Good Safe Bug Spray For Knockout Roses?
Bug sprays designed for traditional roses will also work on Knockouts, but did you know you can use other sprays as well?
Here are some standard bug spray options that work with these beautiful plants.
As mentioned, Knockout roses are a strain of rose bred for lower maintenance and higher disease resistance.
Spectracide Immunox has earned a very positive reputation among chemical sprays. It has the ability to fight some fungal and bacterial infections besides being a contact insecticide.
The big downside to this (and many other) chemical insecticides is they can also kill honey bees and other beneficial insects.
The best time to use Spectracide is at dawn or dusk when your garden’s allies are elsewhere.
Follow instructions to avoid accidentally further harming predator and pollinator species.
Bonide is another trusted product containing 1% percent pyrethrum spray.
Pyrethrum spray is a natural compound extracted from the chrysanthemum. It is safe for use on roses.
Only 5 tablespoons of Bonide is necessary for a gallon of spray bottle. It’s a cost-effective solution for both Knockouts and traditional rose species.
A third trusted option is Safer Brand’s Insect Killing Soap concentrate.
Safer Brand is well-known for pre-mixing natural and chemical insecticides. All you need to do is add water.
Correct measuring is often the difference between a safe treatment and damage to rose plants. So many consumers choose this brand over mixing their own.
By far, the best general insecticide is neem oil.
This natural tree extract contains several compounds that affect insects, some bacteria, and fungi. And they help maintain your plant’s health.
You only need a small amount of clarified hydrophobic neem oil to make a large batch of neem foliar spray.
In spray form, the oil tends to work on contact, suffocating the target insects.
Best of all, neem oil evaporates in an hour or less with no residue, making it safe for use around pollinators and predator insects. Use it only at dusk or dawn.
The only problem most people have with neem oil is the slower results.
Related: More on Neem Oil for Roses
It will take approximately 2 weeks to see real progress due to how the neem interrupts the natural functions of insects upon ingestion.
But the oil is safe enough to use as a preventative measure against future infestations.
Neem foliar sprays need no extra ingredients, but many users like to add horticultural oils or insecticidal soap.
Be warned that these additions may leave behind residue. Also, you will need to make sure any extra ingredients you add are suitable for use on roses.
Neem can even help in the control of Rose black spot disease and powdery mildew.
Do It Yourself Spray
You can also make your own spray, and here’s how to do it:
1. Prepare Ingredients: Gather one teaspoon each of horticultural oil, baking soda, and insecticidal soap.
2. Mix Ingredients: Combine the horticultural oil, baking soda, and insecticidal soap in a quart of water. Stir well to ensure they are thoroughly blended.
3. Transfer to Spray Bottle: Use a funnel to pour the mixture into a clean spray bottle. A transparent bottle helps you see the contents clearly.
4. Apply to Roses: Apply the spray to both sides of the rose bush leaves, as well as the shoots, buds, and blooms. Focus on rose leaves and the underside of leaves to eradicate pests that are present.
By following these steps, you can create an effective insecticidal mixture and easily apply it to your roses for protection.
Don’t want to use the spray?
If you do not want to or cannot use spray for any particular reason, one way to avoid infestations is to plant garlic, chives, catnip, and leeks.
These plants repel aphids due to their strong smell, deterring these pests from approaching.
Some Final Rules Of Thumb
Many types of spray out there might work on varieties of Knockout roses. But it’s always best to play it safe and use only pesticides meant for traditional rose varieties.
It is also a great idea to do a strong spray of water to remove pests. Ensure it’s forceful enough to dislodge insects but gentle enough to avoid harming the rose plant’s leaves and flowers.
Also, consider prevention habits. Use regular neem treatments or spray when you discover signs of pest infestation on nearby plants.
Knockout roses are stunning, and it can be easy to forget that higher resistance doesn’t equate to immunity.
By keeping these tips in mind and using the correct products, you can keep your roses looking beautiful and in peak health for years to come.