What Are the Red Shoots on Roses?

Management Guidelines for RRD

• Remove symptomatic shoots by pruning.
• Discard all diseased foliage immediately in the trash.
• If symptomatic shoots continue to appear, remove the plant.
• If RRD was in the area last year, prune it back heavily in late winter.
• Throw away all of the pruned leaves because they may be home to mites.
• Follow dormant pruning with an application of dormant oil.
• Treat monthly with horticultural oil. As stated on the product label, do not use during times of high temperature.
• Scout and remove wild roses in the area.
• Check for signs of pests on landscape roses in the area and follow these steps if you find any.
• Do not use leaf blowers near roses.
• For new installations, do not overcrowd plantings. Use proper spacing.
• To stop the spread of disease, plant roses and other plants together.
• Irrigating during droughts, keeping fertility high, and controlling fungal diseases are all ways to improve health and vigor.

Miticides to control mite vectors in home gardens are not entirely effective. Monthly applications of horticultural oil may slow the spread of the disease. Commercial landscapers and nursery workers have access to more miticides that are effective at getting rid of eriophyid mites. In places where RRD has been a problem, roses should be pruned hard in late winter or early spring, before the new buds open. Do not prune too early or winter injury may occur. You should pick up the trash by hand, and you shouldn’t use a leaf blower because it could spread mites to other roses nearby. Foliage should be discarded in a sealed bag and disposed of off-site. Since the mites overwinter primarily in old blooms, many mites will be removed by heavy pruning. Following winter pruning, plants should be treated with dormant oil to reduce the population of remaining mites.

The mites will die in a few days in the absence of a host. However, they can survive on fallen debris. Before replanting, it is very important to get rid of and destroy all foliar material, especially dead leaves, flower parts, and buds. The mites may also blow to other roses in the area, both cultivated and wild roses. If the mites or virus are on these roses, it’s likely that a new planting will get them in the future. So, wild roses like the multiflora rose should be taken away because they can hold the virus and/or the mites. Other cultivated roses in the area should be scouted and removed if symptoms are present.

New research proves that the virus is in the roots, so it is very important to cut out the root ball of plants that are infected. Consider a one- to two-month fallow period before replanting roses since some roses can sprout from root pieces. Destroy sprouts if they develop.

When putting in new roses, make sure to carefully check each one to make sure it is healthy and free of signs of pests and diseases, including RRD. Use proper spacing between plants and do not crowd roses. Mites are more likely to crawl from plant to plant if packed closely together. Studies have shown that tall barrier plants can help stop new infections when they are put on the side of the garden that faces the wind.

It is helpful to install a mixed planting using some non-rose material to reduce disease spread. When you plant different kinds of Rosa plants together, you mess up the disease cycle and make it take longer for the disease to spread (Figure 12).

Roses should be monitored throughout the season for symptoms of RRD. If sick plants are replaced, another infection could start if other roses in the area have RRV. So, the best way to manage is to teach whole neighborhoods or communities how to spot the disease and quickly get rid of plants that show symptoms.

Stressed plants are more likely to become diseased. Roses will be healthier and more vigorous if you water them during dry spells, keep the soil fertile by testing it, and get rid of fungal diseases or insect pests as soon as possible.

If RRD is thought to be present in a new part of the state, the plant(s) should be checked for eriophyid mites. The mites are too small to see in the wild, and only a trained professional with a powerful microscope can look at them.

Because of this, clients should cut 6 to 12 inch long symptomatic shoots, preferably shoots with open flower buds. Wrap the shoots in newspaper or dry paper towels and place them in a sealed plastic bag. If the sample is not going to be delivered immediately, it should be stored in the refrigerator. You can bring samples to the county extension office, and they will send them to a specialist to be looked at.

When eriophyid mites are not found, digitals are always helpful because they may show other signs of the problem. If the plants are symptomatic and eriophyid mites are present, the problem is most likely RRD. The diagnostic lab will test to rule out RRV when chemical damage is suspected or when the virus shows up in new parts of the state because it costs a lot to test for.

Snapshot of RRD symptoms

• Elongated shoots
• Red or yellow leaf mottle
• Leaf distortion
• Excessive prickles (thorns)
• Succulent, thickened stems
• Witches’ broom (rosette)
• Flower distortion, discoloration or blight
• Branch dieback
• Reduced winter hardiness
• Increased susceptibility to other diseases

A witches’ broom or rosette is a common sign of RRD. It is made up of a bunch of shoots or branches that all come from the same point or very close to it (Figure 5). Leaves within the witches’ broom may be stunted, distorted, and pigmented red or yellow. You can usually see witches’ broom, leaf discoloration, and/or leaf distortion on at least one branch, but they can spread randomly across the whole plant (Figure 6). The flowers may be distorted, mottled or blighted and fail to open fully (Figure 7). Severely infected plants may not produce flowers. Some cultivars may have new shoots with RRD that get thicker and taste better than the cane they come from (Figure 8). Defoliation and dieback are common with RRD and susceptible rose plants may die in two to four seasons. Infected roses have reduced winter hardiness and are more likely to be damaged in cold winters. Growers often remove the plants prior to death because infected roses are no longer visually appealing (Figure 9).

Plants with RRD are under stress and are weaker than healthy plants. Stressed roses are more susceptible to other diseases such as black spot and powdery mildew. For information about other rose diseases, see Extension Fact Sheet EPP-7607 “Diseases of Roses. ”.

Symptoms of RRD may resemble injury from herbicides. If herbicides touch rose leaves in late summer or fall, the plants may be hurt right away, or the chemical may be stored in the buds. In the latter case, damage becomes evident when buds swell and leaves emerge the following spring. Some herbicides can give roses a witches’ broom look and make their leaves turn yellow or become short and thin (Figure 10). However, excessive thorniness and unusual red pigmentation do not usually occur with herbicide injury. Since most herbicides don’t pick on specific plants, other plants in the area may also change shape and color in strange ways.

Figure 1. Rose rosette disease (RRD) makes rose shoots longer, leaves wilt, and leaves get strange red or yellow spots.

Figure 2. Normal new growth on many roses is red. This should not be confused with symptoms of RRD.

Figure 3. The healthy new growth on this rose has developed into dark green foliage with normal flowers. The part in the middle at the top is affected by RRD; the leaves are still wilting and changing color, and the plant may not flower.

Figure 4. An excessive number of prickles (thorns) on shoots is a symptom of RRD.

Figure 5. Rose shoots with RRD have a group of shoots coming out of almost the same spot on the stem, giving them a witches’ broom (rosette) shape.

Figure 6. One portion of this rose (bottom left) shows witches’ broom and leaf discoloration caused by RRD.

Figure 7. Blooms may show discoloration, mottled color or fail to open normally.

Figure 8. On a normal cane (left), the new shoot has a smaller diameter than the older growth. RRD might make the stem thicker (right), which makes the new growth thicker and more succulent than the older growth.

Figure 9. Diseased roses should be removed, since they harbor the virus and the mite. Often, the plants are not removed until they are visually unappealing.

Figure 10. Leaf distortion and yellowing of a rose caused by drift from herbicide use in the landscape.

Figure 11. The eriophyid mites that transmit RRV are microscopic. Eriophyid mites are present on this magnified rose bud and a few are circled.

Figure 12. Mixed plantings of roses and non-host material may slow the spread of RRD in landscape plantings.

The disease is caused by a plant virus, the rose rosette virus (RRV). This virus has not been transmitted by sap; it is transmitted by grafting or feeding of eriophyid mites. Phyllocoptes fructiphilus is the primary arthropod that transmits RRV. This mite is very small and likes to hide in buds, on open flowers and sepals, at the base of shoots, in the spaces between leaves, or under scars on leaves (Figure 11). The mite acquires RRV when it feeds on infected plants. The disease is transmitted when an infective mite vector feeds on the plant. A few weeks to months after infection, plants will begin to develop symptoms of RRD. Even though the mites can only move short distances on rose plants, wind currents can carry them to new roses. Infective mites can also be carried to new sites on gloves, clothing, or tools. Both the mite and virus are specific to roses (Rosa spp. ); no other hosts have been identified. The mites survive the winter by hiding near or within buds, spent flowers, leaf axils, or leaf scars. It’s possible that the virus won’t do anything during the winter, but symptoms will show up on new growth in the spring.

Management of RRD requires a multistep approach and uses integrated pest management (Table 2). All landscape roses are thought to be susceptible to RRV. Studies are in progress to determine if resistance or tolerance is present in cultivated roses. There is no cure once a plant is infected. Growers have attempted to remove symptomatic canes by pruning, however pruning is often ineffective. The tiny mites may stay on the plant or newly infected canes, which may not show any signs of illness for months, or the virus may live in the roots. So, plants showing signs of the disease should be cut down as soon as possible, including the root ball. Dead heading roses throughout the season may be useful since mites accumulate around the open blooms. Maintaining proper health and vigor of roses in the landscape may be helpful.

Why New Leaves on Roses Red? |Daphne Richards |Central Texas Gardener

What are the symptoms of rose rosette disease?

The main symptoms are vigorous red shoots, distorted leaves, bushy clusters, and defoliation. It can be difficult to differentiate between healthy new growth and the symptoms of Rose Rosette Disease. Many panicked gardeners share pictures of suspected infection, only to be reassured that their rose is pushing out normal new shoots and canes.

Are red leaves on a rose bush normal?

Red leaves on a rose bush can be normal to the growth pattern of the bush, however, this can also be a warning sign of big problems. It is good for the rose-loving gardener to know the difference between normal growth and the warning of a big problem that has come to your home garden or rose bed.

Why is my rose bush turning red?

This damage can cause the foliage on the rose bush to change coloration as the foliage dies, turning it red in color, which then tends to turn a mottled red and yellow coloration. This, too, is a normal thing to witness in the rose bed or garden as the weather changes with the seasons.

How do you know if a Rose is damaged?

Deformed, crinkled, and brittle leaves with yellow mosaics and red pigmentation. Small leaves and shrunk petioles along with short and intensely red shoots on roses. Plant gets damaged in slightly cold weather. Thickened roses with a rapid increase of thrones. Rose stems turning red and getting vulnerable to natural damages.