Rose of Sharon & Japanese Beetles
The Rose of Sharon is an impressive plant with attractive green foliage and a showy display of large flowers. It is also particularly attractive to Japanese beetles. They love to feed on the plant and can do considerable damage, if left unchecked. Physical, chemical and biological methods can be used to protect a Rose of Sharon tree from the attack of Japanese beetles.
Rose of Sharon
The Rose of Sharon is a tall, tree-like shrub that can grow to more than 10 feet tall. The plant displays many large, showy blossoms that can range from white, to pink, red, blue, or purple, and there can even be different colors on the same plant. The foliage is also striking, with large, glossy, serrated leaves. Rose of Sharon grows best within hardiness zones 5 through 9. Once established, it needs little attention.
Japanese beetles are one of the most damaging of garden pests. Adult beetles are about a half inch in length. They are scarab-like, with metallic-green heads and copper-colored wings. They feed on about 300 species of plants in the United States, Rose of Sharon among them. The beetles usually feed in groups that are attracted to the plants from the odors emitted by damaged leaves. The beetles will eat leaves, flowers and wounded or overripe fruits. The grubs of the beetle grow underground, feeding on roots that damages plants.
Physical Removal and Protection
Small Rose of Sharon plants can benefit from having the beetles removed by hand. This can be accomplished by simply shaking the branches over a bucket of soapy water in the mornings when the beetles are slow. Netting can also be used to protect small Rose of Sharon plants from further infestation.
The Rose of Sharon can also be treated for Japanese beetle infestations with insecticides such as cyfluthrin, bifenthrin, cyhalothrin, permethrin or carbaryl. The protection these sprays provide usually lasts about two to three weeks. Insecticidal soaps, orange peel and other home remedies are largely ineffective against Japanese beetles. The foliage should be completely sprayed with the insecticide. Repeat application may be necessary. Spraying the soil around the base of Rose of Sharon plants can also help to reduce the risk of damage from the grubs.
Japanese beetles can also be caught in large numbers in specifically designed traps that are sold at garden centers and nurseries. They contain baits that either mimic the smell of female beetles or a food source. The traps can be hung away from the Rose of Sharon. The beetles are attracted to the smell, enter the trap and die. Sometimes this approach can backfire, however, attracting far more beetles than the trap can accommodate.