Common Disease Problems
Black Spot: A fungal disease that affects the leaves. It usually occurs during hot, humid or rainy summers. Black circular leaves appear on the upper and underside of leaves. The outer margins of the circles are ragged. The spots can enlarge and merge. The leaves often fall off the plant and the plant may be defoliated. Burpee Recommends: Remove all debris from under the plants. Avoid getting the leaves wet. A mulch under the plants will prevent spores from splashing up. Rosa rugosa is very tolerant of black spot.
Powdery Mildew: This fungus occurs on the top of the leaves in humid weather conditions. The leaves appear to have a whitish or greyish surface and may curl. Burpee Recommends: Avoid powdery mildew by providing good air circulation for the plants by good spacing and pruning.
Rust: A number of fungus diseases cause rust colored spots on foliage. Burpee Recommends: Remove infected plant parts. Contact your Cooperative Extension Service for recommendations.
Common Pest and Cultural Problems
Aphids: Greenish, red, black or peach colored sucking insects that can spread disease as they feed on the undersides of leaves. They leave a sticky residue on foliage that attracts ants. Burpee Recommends: Introduce or attract natural predators into your garden such as lady beetles and wasps who feed on aphids. You can also wash them off with a strong spray, or use an insecticidal soap.
Deer: Plants may be eaten to the ground. Burpee Recommends: Try a deer repellent or physical barrier for young plants.
Scale: Small bugs look like brown, black, gray to white bumps on the stems of plants. Scale may not have any apparent legs and may not move. Scales have a sucking mouth part. Scale may produce honeydew so leaves and stems may be sticky. Scale can weaken the plant causing it to grow very slowly and may wilt at the middle of the day. Burpee Recommends: Completely spray the stems with Insecticidal soap.
Spider Mites: These tiny spider-like pests are about the size of a grain of pepper. They may be red, black, brown or yellow. They suck on the plant juices removing chlorophyll and injecting toxins which cause white dots on the foliage. There is often webbing visible on the plant. They cause the foliage to turn yellow and become dry and stippled. They multiply quickly and thrive in dry conditions. Burpee Recommends: Spider mites may be controlled with a forceful spray every other day. Try hot pepper wax or insecticidal soap.
When will I get fruit? You should begin to get fruit the second year after planting. If your plants bloom the first year, it is best to remove the flowers to keep the strength in the plant.
What parts are edible of the Rosa rugosa? The rose hips as well as the rose petals are edible.
How do I get more flowers during the summer? To get more flowers through the summer months, remove the spent blooms. If you do this, however, you will sacrifice the first crop of hips. Stop deadheading in late summer to let the hips form in the fall.
Can I plant Rosa rugosa at the seashore? Yes they tolerate wind and salt spray. Their tolerance to salt also makes them ideal for planting close to the street where they may get exposed to road salt as well.
I sprayed my Rosa rugosa with a pesticide or fertilizer and now all the leaves are falling off what do I do? Rosa rugosa does not tolerate its leaves being sprayed by chemicals; do not spay the leaves. Fortunately Rosa rugosa is very disease and insect tolerant and usually does not need to be treated.