Pests & Diseases

Voles are eating the roots of My Knock Out® Roses.

Traps and poisons are the two most successful methods of controlling voles. If you want to try the organic route, there is a product called Shake-Away Rodent Repellent which uses the scent of fox urine to discourage voles from burrowing into the soil beneath your roses. The product is in a powder form that can be sprinkled around the roses you wish to protect.

What steps can be taken to treat powdery mildew?

Powdery mildew can be a common problem of roses, particularly when conditions are favorable in spring and fall. Powdery mildew is a fungal disease that appears as a soft white coating on stems, leaves, and buds of rose bushes. It commonly occurs when there are many overcast days with high humidity and mild temperatures. Generally speaking, powdery mildew becomes less of a problem after the arrival of summer which typically brings with it long, hot, sunny days. The mildew problem will go away with improved weather conditions. There are a few options for correcting the problem.

1. An application of horticultural oil should smother the spores and reduce spread of the problem. It is best to try this as soon as possible upon visible symptoms. An early sign of powdery mildew is a slight curling upwards of the foliage.

2. You could try trimming back the worst affected areas and wait for new, clean growth to flush out.

My Knock Out® Roses are starting to get black spot.

In some very humid, black spot prone areas, you may see some black spot. Don't worry--while the plant may drop some leaves, it won't be detrimental to the overall health of the plant. Make sure when you water your roses, that you water at the base of the plant. Watering overhead (with a sprinkler or hose), leaves water on the foliage which is an invitation for fungal disease. Your Knock Out® Roses will be much happier if you water at the base of the plant. Also, they prefer a long drink of water every once in a while rather than frequent small watering.

The deer have eaten most of the blooms on my Knock Out® Roses. Will they bloom again or are they a total loss?

Knock Out® Roses are not deer resistant and unfortunately, as you probably know, when deer are hungry, they ll munch on anything. Don't worry though, Knock Out® Roses are really tough. They bloom repeatedly from spring through frost, so hopefully when it's time for them to bloom again, you will see more flowers. You may want to try a product like Liquid Fence to keep the deer away.

Do we need to protect our Knock Out® Roses from being eaten by insects?

Knock Out® Roses are not pest-resistant, but they are extremely tough so even if bugs get after them, they should be fine. You can use a spray product formulated for roses if the bugs are particularly bad in your area. The best way to remove Japanese Beetles is by hand though--pick them off one by one and put them in a container of warm soapy water. Placing a bird feeder nearby can also be effective!

There are holes in the leaves of my Knock Out® Rose. They are not only on the edges and I don't see any beetles or other bugs. They are not symmetrical holes, either. Any tips?

The leaf damage you are seeing could be from what's called rose slug (also called sawfly). Look on the underside of the leaves. Do you see any tiny green inchworm looking critters? Rose slugs will chew the leaves of plants--leaving trails where they've munched through, but they won't be detrimental to the overall health of your Knock Out® Roses.

Watch this video to learn more

Japanese Beetles are attacking my Knock Out® Roses.

Pick each Beetle off and drop them into a bucket filled with warm soapy water. Putting a bird feeder nearby may also help. Japanese Beetles won't be detrimental to the overall health of the plant so if you can stand them, it's fine to leave them alone too. You may want to try a product like Milky Spores to control them--we recommend just pulling them off one by one though (not fun but effective)!

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