Pests on Knockout Roses
According to horticulturists at Louisiana State University, knockout roses, first introduced by breeder William Radler in 2000, have become the most popular variety of roses in the country. A big part of the success of this group of hybrid shrub roses is its superior resistance to pests and disease. However, no plant is entirely immune to pest invasion, so proper planting and care is important to ensuring that the plants will remain strong enough to live up to their reputation. Does this Spark an idea?
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Common Rose Pests
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Japanese beetle at work. The four most common pests of roses are aphids, Japanese beetlles, rose chafers, sawfly larvae and rose midge.
Symptoms of Rose Pest Infestation
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Rosebud infested with aphids. The obvious symptom of pest infestation of roses is the presence of insects on the flowers, foliage or stems of the rose bush. Aphids generally cluster on the stems and shoots of rose bushes, while Japanese beetles, with their characteristic metallic green bodies and copper-colored wings, can be found on leaves or stems. Skeletonized leaf surfaces and partially eaten blooms are another sign of their presence. Rose midge causes buds to blacken and die.
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Cultural Control
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Well-tended roses. Especially with disease-resistant plants like knockout roses, the best way to guard against pest infestation is to maintain your plants under ideal conditions. For knockout roses, this means planting the bushes in a sunny location--one that receives at least 4 hours of full sun per day--and making sure the soil is moist and well-drained.
Knockout rose bushes should be pruned about every three years in the early spring. This means removing or cutting back some of the longest and oldest branches. Between regular prunings, dead wood can be removed any time it is observed.
Treating Pest Infestations Without Chemicals
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There are many ways to treat pest infestations on roses without using chemical pesticides. Some pests can be hand-picked and disposed of in soapy water or simply sprayed away with a hose. Blackened buds or shoots should be removed and disposed of. If you plan to display roses from a bush that has been troubled by insect pests, you may even bag the blossoms with clear plastic until they are ready to be cut.
Pesticide Control
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If chemical control of rose pests does become necessary, use the mildest available products. For aphids and spider mites, this is generally insecticidal soaps that are available at any good gardening store. Experts at the Alabama Cooperative Extension System recommend carbaryl to control beetles and caterpillars on roses. Use any pesticide only according to package directions and follow all recommended precautions.
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References
Resources
- Photo Credit rainbow roses image by Photoeyes from Fotolia.com Japanese Beetle image by Jim Mills from Fotolia.com aphids on a rose bud image by Renata Osinska from Fotolia.com wet rose image by jimcox40 from Fotolia.com
