Rose Aphids & Japanese Beetle Pests of Roses

- Roses host a variety of noxious pests -

Summary: Roses can be difficult to grow because of the many insect pests and diseases that plague this garden favorite. Aphids and several leaf-feeding beetles can be the most damaging but fortunately there are now relatively low toxicity solutions to these pests.

Jack DeAngelis, PhD

OSU Ext. Entomologist (ret.)

Aphids & black spot fungus on rose

Roses are host to a wide range of insect and disease pests. The following Oregon State University Extension publication "Controlling Disease and Aphids on Your Roses" was published in 2000 and gives basic information about rose care. A pdf version also is available (click on "print version" link to download the pdf file).

For most gardeners aphids and black spot leaf fungus will be your main concerns. Another fungus, powdery mildew, can become a problem for some roses, in some years. The very best treatment for aphids is overhead watering combined with insecticidal soap. Use the "wet-soap-rinse" procedure described in the spider mite control article (see Related Articles below). Soap works great and is non-toxic to you and to beneficial insects and mites.

Peace Rose, Photo by Elizabeth DeAngelis

Japanese beetles and roses

In some regions (including the eastern US) Japanese beetle and rose chafer are severe pests of rose (see Related Articles below). Adult beetles can do significant damage to foliage and flowers if left untreated. Adults emerge in early summer and immediately start to feed on a wide range to host plants but rose is one of their favorites.

Many rose gardeners combine hand-picking with a foliar (leaf) spray of insecticide when beetles are present. A good choice for an insecticide in this situation is EcoPCO WPX (see below). As a wettable powder EcoPCO WPX is easy to apply with a garden sprayer, relatively low toxicity and easy on beneficials at least compared to conventional insecticides.

Insecticides and traps

Japanese beetle (Popillia japonica) can be a severe pest of roses but this beetle does not occur in all regions. Check with your county Extension office or garden center for local information about this pest. If Japanese beetle does occur in your area use Japanese beetle traps to detect when adults emerge and then treat foliage to prevent feeding injury. Also, be sure to check the article below for other ways to control this pest.

New botanical insecticides like EcoPCO WPX (right) can be safely used for Japanese beetle control on roses. See label instructions for this application and please read and carefully follow these instructions. Apply when beetles start feeding in early summer or when your traps start to collect beetles. Re-apply as necessary. Hand-picking beetles into soapy water also is effective.

Related articles

+ What are Japanese Beetles?

+ Using Insecticidal Soap Against Aphids & Spider Mites

+ Managing Aphids on Garden Plants

+ Managing Spider Mites on Garden Plants

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