Aphids, Mites, Scale & Whiteflies
Aphids reproduce rapidly and like tender new growth. Spider Mites are found on the undersides of leaves and may cause stippling damage. Scale have dome-shaped armored coverings and attach to stems of roses that are grown in damp or shady conditions. Whiteflies are found in warmer climates or greenhouses and typically feed on the underside of leaves.
- Orange Oil Cleaner – Dilute 1 teaspoon per gallon of water. Use as needed by spraying on leaves thoroughly. Wet leaf surfaces until the cleaner drips off of them.
- Soap Spray – Mix ½ teaspoon mild dish soap and 1 teaspoon cooking oil in a 1-quart sprayer filled with water. Spray liberally over the entire plant.
- Ladybugs – To keep aphids in check, release ladybugs on the affected plant. They will stay as long as there is shelter and host bugs to feed on.
- Blast with Water – Insects may also be dislodged by a strong jetstream of water.
Slugs & Snails
Slugs and snails can wreak havoc on roses and love to eat the foliage of young plants. They begin feeding in early spring and continue through the growing season until frost and can be quite a nuisance.
- Beer – Pour an inch of beer into the bottom of a shallow can or dish. Set it in the garden. Slugs and snails, attracted to the yeast in the beer, crawl in and drown.
- Handpick – Collect at night and remove from the garden area.
- Coarse Sand, ¼”-minus Gravel, or Hazelnut Shells – Apply sand or gravel in trails around roses, or topdress beds with crushed hazelnut shells. Slugs and snails prefer not to cross abrasive surfaces.
Powdery Mildews, Blackspot & Rusts
Powdery Mildew appears as light gray or white, powdery spots. It is transferred by wind and needs to be treated quickly to prevent spreading to other plants.
Blackspot is caused by a fungus and spreads by rain or overhead watering and may cause leaf drop if untreated.
Rust commonly occurs in the spring and fall and first appears as small orange spots on the leaves and can cause leaf drop if untreated.
Powdery Mildew, Blackspot and Rust all thrive in warm temperatures and high humidity.
- Baking Soda Spray – Mix 1 tablespoon baking soda and 1 teaspoon cooking oil in 1 gallon of water. Place in a spray bottle or tank sprayer and apply liberally. Repeat as needed.
- Sanitation – Remove infected leaves and destroy. Do not compost. Keep the ground surrounding your roses free of leaf debris and weeds.
- Cold Water – For Powdery Mildew, spray affected leaves with cold water early in the morning and allow leaves to dry in the sun
Keep an eye out also for yellowing leaves in the spring and summer. This is the plant's way of communicating a problem to you. If your rose is showing yellowing leaves in the fall, this is normal and not a problem.
- If yellow leaves fall when tapped, your plant has too much water.
- If yellow leaves stay on when tapped, your plant is too dry.
- If the yellow leaves are crunchy, your plant is too dry and too late to save. Cut back as needed to promote regrowth.