Insecticide for Rose Bushes

Insecticides can harm helpful insects, too.

Maintaining a proper schedule of insecticide treatment can be the difference between award-winning rose bush blooms and a completely lackluster season. Rose bushes can survive without insecticide treatment but you may be disappointed by the results. Prevention is key as some insects carry diseases from which, once afflicted, your rose bush is not likely to recover.

Types

General-purpose insecticide preparations are available at garden centers. These insecticide mixes can be used to treat or prevent an infestation. When dealing with an infestation, look for a supplemental insecticide specific to the insect. According to Clemson University's Home and Garden Center, the pest should first be identified and treatment should begin with the least toxic chemical.
With a little knowledge of the most common pests of rose bushes and the insecticide sprays to use against them you are well on your way to protecting these beautiful plants.

Aphids

A variety of aphid species are well-known pests to any gardener but to the rose bush grower the rose aphid, or Macrosiphum rosae, is likely to be the culprit. The insect is about 1/8-inch long, soft, pear-shaped and pink or green.
Insecticidal soap alone can be effective against aphids when sprayed directly onto the insects. Any products containing one or more of the following insecticides are also affective: bifenthrin, cyfluthrin, esfenvalerate, horticultural oil, insecticidal soap, lambda cyhalothrin, malathion, neem oil, permethrin or pyrethrin.

Japanese Beetle

These hard-shelled beetles are mostly black with metallic green and gold colors. They feed on the buds and flowers and may also attack the leaves. Traps for the beetles should be used with caution as they can end up attracting more beetles, thereby escalating the infestation. If you use traps keep them at least 50 feet from the plants.

Look for insecticide spray preparations containing one or more of the following: bifenthrin, carbaryl, cyfluthrin, esfenvalerate, lambda cyhalothrin, malathion, neem oil, permethrin or pyrethrin.

Mites

More of a spider than an insect, these tiny pests can be difficult to see with the naked eye. If you notice yellow or white spots on the leaves or can see a fine web on the underside of a leaf, you may have a mite infestation.

Mites can be controlled by using insecticidal soaps and horticultural oil. Make sure when treating the rose bushes to cover all surfaces.

Thrips

Tiny brown insects, thrips live and feed inside the flowers. Thrips are more attracted to lighter-colored roses and can be detected if you are finding misshapen blooms and damaged petals. Try blowing into the flower and look for movement of the insects if suspected.

While the first step to dealing with a thrips infestation is to remove all affected blossoms, insecticides can assist in winning the battle. When using an insecticide spray it must be applied prior to the buds being invaded. Insecticidal soap may be used as well as products containing one or more of the following: acephate, bifenthrin, cyfluthrin, esfenvalerate, lambda cyhalothrin, permethrin or spinosad.

Rose Scale

Although several species of scale can attack rose bushes, Aulacaspis rosae, or rose scale, is the most prevelant. Scales produce a waxy secretion that covers the adult and can make it difficult for insecticides to penetrate. The young scales are susceptible to insecticide spray treatment.

Horticulture oil can be used against the mature scales. For the immature scales, any product containing one or more of the following will be effective: acephate, bifenthrin, cyfluthrin, esfenvalerate, lambda cyhalothrin, malathion or permethrin.

References

• Clemson University's Home and Garden Center: Rose Insects
• University of Illinois' Rose Garden: Insect Pests