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Figure 1. Ringspot patterns on rose leaves. |
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| Figure 2. Vein clearing symptoms associated with rose mosaic |
| Two important diseases on rose plants are rose mosaic virus and rose
rosette virus.
ROSE MOSAIC VIRUSRose mosaic virus is fairly common in Kansas rose gardens. It has a wide range of symptoms, including ringspots, wavy lines, chlorotic vein banding, an oakleaf pattern, a mosaic pattern, and a yellow net pattern. Symptoms start showing up late spring and are present throughout the growing season. Symptom expression varies with the cultivar and the time of year. Some plants infected with rose mosaic virus remain symptomless. Transmission of the virus is through vegetative propagation of infected plant material. Infected grafting material can include buds, scions, or root stocks. It is also suspected that the disease can be spread through virus-infected pollen, although this is not considered a very important or successful avenue of transmission. An important point to remember about virus-infected plants is that once they become infected, they remain infected for the life of the plant. Rose plants with rose mosaic virus tend to be more susceptible to winter injury. Although the virus produces unsightly foliage and tends to reduce plant vigor, it will not kill the plant. There are no practical control measures for virus-infected plants. Severely diseased plants should be removed and destroyed. Certified disease-free roses should be purchased whenever possible.
ROSE ROSETTE VIRUSRose rosette is a more destructive virus disease than rose mosaic virus. It is a serious problem in Kansas on wild roses (Multiflora sp.). It has also been found occasionally in domestic rose plantings. Infection is thought to start with rapid elongation of a new shoot. The rapid shoot growth may continue for several weeks to a length of two to three feet. Following shoot elongation, a witches' broom or clustering of small branches occurs. The stems develop excessive thorniness and produce small, deformed leaves with a reddish-purple pigmentation. Stems and petioles of multiflora sp. may have reddish blotches or streaks.
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Figure 3. Purple, distorted foliage assoicated with rose
rosette. |
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Figure 4. Prolific thorn production resulting from
rose rosette. |
| The mechanism of virus transmission has not been confirmed. It is
suspected that the virus is transmitted by an eriophyid mite.
Rose plants infected with the rose rosette virus die rapidly, usually within one to two years. Again, there is no effective control measure for virus-infected rose plants. In garden settings, infected plants should be removed and destroyed.
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Web updated 9/01/06 |