Roses have a number of potential problems that can make them more difficult to grow. Planting them in a good garden location and selecting a winter-hardy and naturally disease-resistant cultivar is the best way to avoid many problems.
Learn more about the potential disease, insect, and animal pests, as well as the environmental conditions that can negatively affect roses and how to manage them below.
Several common disease problems detract from a rose’s natural beauty. Disease organisms can cause unsightly leaves, poor flower production, and even death of leaves, canes, or entire plants. Identifying the fungus, virus, or bacterium causing the problem is the first step to solving it.
More information about common rose diseases can be found in this publication: Common Rose Diseases.
Black spot is a common fungal disease on roses that can be identified by the roughly circular black spots on the upper surface of the leaves. Infected leaves eventually turn yellow and fall prematurely.
Learn more about identifying and managing this disease in this article: Rose Black Spot.
Powdery mildew is a widespread disease of roses. The disease is easily recognized by the white powdery appearance of infected leaves, twigs, and flower buds. Infected leaves may also appear distorted and fall from the plant.
Learn more about identifying and managing this disease in this article: Powdery Mildew - Ornamental Plants.
Rose Mosaic Virus
Rose Mosaic is a viral disease. The symptoms are varied but often include yellow (chlorotic) line patterns, yellowing that occurs in circles (ringspots), or irregular areas of yellow and dark green tissue, giving a mottled appearance. Stunted plant growth also may occur.
Learn more about identifying and managing this disease in this article: Rose Mosaic.
Crown gall causes round galls to form on stems or roots, often near the soil line of the plant. Galls may vary from the size of peas to over an inch in diameter. Galls can interfere with the plant’s ability to move water and nutrients through the stem, which may result in stunting or decline of the plant.
Learn more about identifying and managing this disease in this article: Crown Gall.
Rose Rosette Virus
Rose rosette is a fairly common disease of roses that can cause significant damage. Although more commonly known on weedy multiflora roses, it is also found on cultivated roses Symptoms of rose rosette can vary greatly but typically include rapid growth of shoots, "witches' brooms" (tufts of branches growing close together), development of tufts of small, deformed, reddish leaves, and excessive thorniness.
Learn more about identifying and managing this disease in this article: Rose Rosette.
Mossy Rose Gall
Mossy rose gall is aptly named as it is a moss or thread-like growth that develops on the leaves. These abnormal growths are caused by insects but look much like a disease. You cannot readily see the insect, but you can see the abnormal growth they cause. Mossy rose galls formed on the leaves of the rose are harmless.
Learn more about identifying and managing this disease in this article: Mossy Rose Gall.
Rose rust causes leaves to turn yellow, starting near the bottom of the plant. Powdery orange to black spots form on the underside of the leaves with a corresponding yellow spot on the upper surface. As the disease progresses, it causes leaf drop. Rose rust is more common in the cooler spring and fall months as it prefers mild temperatures and wet conditions, but it can also form during the summer months.
Learn more about identifying and managing this disease in this article: Rose Rust from the University of Wisconsin.
Cankers cause dark sunken areas to develop on the stems. The fungus responsible for these symptoms will kill the stem tissue causing the portion of the stem beyond the canker to wilt and die.
Learn more about identifying and managing this disease in this article: Canker on Roses, Shrubs, and Vines from the University of Maryland.
Large beetles emerge from mid-June through July with a shiny metallic green head and thorax and coppery red wing covers. Beetles are typically found in clusters feeding on flowers and foliage of a wide variety of plants, including roses. Populations can be very large. Foliage is consumed by eating the tissue between the veins but leaving the veins, a type of feeding called skeletonization. Flowers and fruits may be devoured completely and plants often turn brown in August because of the feeding damage.
Learn more about identifying and managing this insect pest in this article: Japanese Beetle.
The larvae of roseslug eat the soft part of leaves, leaving behind a network of veins and one epidermis layer. The exposed epidermis quickly turns brown and crisp. Because the leaf's veins are left intact, the damage is called skeletonization (the “skeleton” of the leaf remains). This damage may also be called “window-paning.”
Learn more about identifying and managing this insect pest in this article: Rose Sawfly - Roseslug.
Leafcutter bees create circular holes 1/2 inch or less in diameter cut from the edge of rose leaves and flowers. The cuts are very neat and nearly perfectly round, making the holes appear “punched out” with a large paper punch. Control for these beneficial insects is not recommended.
Learn more about identifying and managing this insect pest in this article: Leafcutter Bees.
Small, soft-bodied green or pink insects are found in clusters on shoot tips or flower buds. Aphids secrete sticky honeydew that accumulates on lower leaves and can attract ants and turn black with sooty mold.
Learn more about identifying and managing this insect pest in this article: Rose Aphid from the University of Minnesota.
Thrips cause white or brown streaks in flowers and/or irregular streaks on the upper surface of the leaves. In severe infestations, foliage or flowers can become deformed. Insects are very small (1-2mm) and often cannot be seen without magnification.
Learn more about identifying and managing this insect pest in this article: Thrips from the University of Illinois.
Feeding injury from spider mites causes the foliage to be discolored with very tiny yellowish-green speckles. Severe damage causes “bronzing” or "bleaching" and damaged leaves may drop off the plant. Close examination of infested foliage may reveal very fine webbing on the stems at the base of the needles.
Learn more about identifying and managing this insect pest in this article: Two Spotted Spider Mite.
Feeding by scale insects may cause yellowing or wilting of leaves, stunting or unhealthy growth, and eventually, death of all or part of the plant when infestations are heavy. Scale insects also secrete sticky honeydew that accumulates on lower leaves and can attract ants and turn black with sooty mold.
Learn more about identifying and managing this insect pest in this article: Scale Insects.
Corn rootworm beetles wandering away from corn fields are frequently a late-summer pest in gardens where they feed on flowers and vegetables, including roses. Beetles can ruin flowers by feeding on the moist buds or petals.
Learn more about identifying and managing this insect pest in this article: Corn Rootworm Beetles on Flowers in the Fall.
Two common garden animal pests can cause extensive damage to roses. During the growing season, deer browse plants eating flower buds and foliage (despite the thorns!) Rabbits can cause similar damage, eating branch tips, leaves, and emerging shoots. Damage can be more severe in the winter when other food sources are limited.
Management of these animal pests looks similar in winter and during the growing season. Exclusion is the most effective. This can include fencing, wraps, or caging of the plants. Repellents often have limited success. Taste repellents, such as capsicum, and area repellents, such as rotten eggs or predator urine, must be reapplied often as they are easily washed off. They also should be rotated or switched frequently as animals quickly get used to (and start to ignore) the repellent.
When animal pest pressure is high enough, growing something other than roses that are less palatable or less likely to be browsed may be beneficial.
More information about managing these pests, including specifics on fencing and the use of other management techniques, can be found in these links:
- How to Protect Trees and Shrubs from Animal Damage Over Winter
- Rabbits: Damage Management
- White-tailed Deer: Damage Management
- Susceptibility of Plants to Rabbit Damage
- Susceptibility of Plants to Deer Damage
When roses are growing in less-than-ideal conditions, experience weather extremes, or are not cared for properly, problems can occur. These issues are sometimes difficult to identify because roses experiencing issues related to site conditions or care are stressed and weakened, making them more susceptible to insect and disease issues. It is important to identify the primary cause to fix the problem.
Most roses will see some winter dieback in Iowa. For hardy shrub, landscape, species, and miniature roses, it may only be a few cane tips and rarely negatively impacts the overall health or blooming of the plant. For non-winter-hardy roses, like hybrid tea, grandiflora, floribunda, and some climbing types, the dieback on the plant can be extensive when they are not protected. This is especially problematic for grafted roses because the upper portion (scion) may be completely killed. After the new growth begins in spring, prune out dead stems back to living tissue.
Roses that see winter dieback must be protected over the winter to minimize the damage. Learn more about protecting roses in winter in this article: How to Overwinter Roses in Iowa.
Suckers & Vigorous Rootstocks
Most hybrid tea, grandiflora, and floribunda roses are grafted. The desirable cultivar is grafted to a rootstock. The rootstock, while similar, often does not look the same. It may bloom poorly or have flowers that look drastically different. Flowers from rootstock are often small, with a single set of petals (usually light pink) surrounding a tuft of yellow stamens. The point where the showy cultivar (the upper portion or scion) attaches to the rootstock is called a graft union. The graft union resembles a swollen knob or bump on the stem.
When above-ground growth from the rootstock (the portion below the graft union) is allowed to grow, it can be very vigorous and quickly overtake the desirable cultivar. This can effectively change the growth habit and flowering of the plant. Sometimes the scion will die (often due to cold temperatures) and the only living portion left is the rootstock which then easily grows new canes.
Suckers and any growth from any point below the graft union should be pruned out as soon as it is noticed. Do not treat the cuts with herbicide, as it could damage the plant's overall health. Pull soil away from the base of the plant if necessary to cut the sucker off as close to the base as possible.
Several factors can cause poor bloom on roses, including,
- Roses not in full sun (plant roses in locations that receive 6+ hours of direct sunlight a day)
- Too much fertilizer, which can cause excessive growth and few flowers (fertilize at the appropriate rate and time of year)
- Stressful environmental conditions, such as too little moisture, excessively hot temperatures, etc. (provide supplemental irrigation if needed and plant roses in a location that is best suited for their growth)
- Improper pruning (be sure to prune roses at the right time according to their type)
- Excessive winter kill (provide winter protection)
- Improper deadheading/lack of deadheading (deadhead at the appropriate time/remove spent flowers to encourage new growth)
- Some types or cultivars are not rebloomers and only bloom for a limited period or may have a large flush of blooms and then only flower sporadically the rest of the season (plant a different type of rose)
Pale, Yellow Leaves
When leaves are chlorotic (yellow) or have interveinal chlorosis (green veins, but yellow in between) can be caused by improper fertilization, shady conditions, or root damage caused by overwatering or poorly drained soils. More information on the proper care of roses can be found in this article: Growing Roses in Iowa.
Brown Leaf Edges
Brown leaf edges or brown, dry leaves can be caused by underwatering, drought conditions, excessive heat, or excessive fertilizer applications. More information on the proper care of roses can be found in this article: Growing Roses in Iowa.
- All About Roses
- Growing Roses in Iowa
- Rose Types and Cultivars for Iowa
- A Brief History of the Rose
- How to Select and Use Roses in the Garden
- How to Prune Roses
- How to Overwinter Roses in Iowa
- How to Plant and Transplant Roses in Iowa
- How to Propagate Roses
- Rose FAQs
- Caring for Roses in Iowa (publication)
- Miniature Roses (publication)
- The Griffith Buck Roses (publication)
- Griffith Buck: Rose Hybridizer (publication)
- Roses for the Home (publication)
- Common Rose Diseases (publication)
- Flowers and Their Meanings: The Language of Flowers
- State Flower of Iowa