Oso Easy Cherry Pie rose. Photo courtesy Proven Winners
As rose troubles continue to plague gardeners, we will look this week at a few more common problems. Last week, we covered black spot, anthracnose, rose mosaic virus and rose slugs.
Japanese beetles tend to congregate on the flowers, buds and leaves of roses and hundreds of other plants. The beetles skeletonize the leaves. Photo courtesy Kansas State University Extension
Japanese beetles. Pretty soon, it will Japanese beetle season, that is if any of the pupae survived the winter to emerge as the attractive, green metal bugs.
These bugs skeletonize the foliage of roses and 400 other types of plants. They also dine on flower petals. Frequently, systemic insecticides are recommended to control Japanese beetles, but these products are nonselective, meaning they kill bees, butterflies and other pollinating insects along with bugs we don’t want. Try these methods instead:
- Remove any damaged leaves and flowers and soon as you notice them. Holey leaves and chewed petals are like neon signs and attract more beetles to the feast.
- Spray the plants with a strong stream of water to knock off the beetles.
- In the mornings, knock the beetles into a bucket of soapy water and dispose.
- When startled, the beetles fall to the ground. Take advantage of this by placing newspapers or cloth under the roses and shake the plants. Slide the bugs from the paper or cloth into a bucket of soapy water and dispose.
Although not deadly, powdery mildew weakens a plant, making it susceptible to other diseases or insects. Photo courtesy University of Kentucky Extension
Powdery mildew. Besides roses, a lot of plants get this fungus disease, including lilac and garden phlox, with some being more susceptible than others. This disease creates a whitish or grayish powdery coating on the foliage, stem and flower buds. Although not deadly, it is unsightly and may weaken the plant.
To control this disease, plant roses in full sun and with good air circulation. Once mildew hits, there’s nothing that will get rid of it. Fungicides may keep the disease from spreading to healthy leaves. Remember that fungicides are particularly deadly to bees, so always follow the label directions.
Webs on plants are another sign of possible spider mite infestation. Yellow or orange stippled leaves are another common symptom.
© Dreamstime.com/Taviphoto
Spider mites. Spider mites cause tiny orange, white or cream dots on the leaves, called stippling. Mites may show up when it’s hot and dry. Knock them off with a strong spray of water from the hose.
A hard spray from the hose is a quick and easy way to knock aphids off of roses and other plants without the need for insecticides. © Dreamstime.com/Armando Frazao
Aphids. Sometimes called plant lice, these slow moving insects suck the life out of plants, causing distorted leaves and flowers. Aphids can be lots of different colors and are easy to see. Control with a hard spray of water from the hose. There are lots of predatory insects, such as lady beetles, that feed on aphids, so a non-selective insecticide is not usually recommended.
Roses may have other problems, so look for disease- and insect-resistant plants and know what you have before you treat it. And remember, a few blemishes are nothing to worry about. Mother Nature is not perfect, either.