Cause Several viruses are associated with the range of symptoms of rose mosaic, including Prunus necrotic ringspot virus (PNRSV), Apple mosaic virus (ApMV), Arabis mosaic virus (ArMV), and Strawberry latent ringspot virus (SLRSV). The disease does not spread naturally and has no known insect vector, but grafting transfers it to healthy plants. Transmission of ArMV and/or SLRSV could occur by Dagger nematodes but this has not been extensively studied. Viruses can be in the rootstock or scion or both and may not show symptoms. 'Madame Butterfly', 'Ophelia', and 'Rapture' are highly susceptible. Some report the disease does not spread; others indicate it may spread very slowly over many years. Root grafting between infected and healthy plants can also spread the disease. Cuttings from virus-infected mother plants had 35% reduction in rooting.
Symptoms Symptoms may range widely depending on time of year, temperature, and type of virus(es) infecting the plant. Characteristic symptoms include chlorotic line patterns (zigzag pattern), ringspots, and mottles in leaves sometime in the growing season. There may also be yellow net and yellow mosaic symptoms. Symptoms often are evident in spring and early summer but may not be on leaves produced in summer. Vein-banding may be on leaves in long hot periods. Flower distortion, reduction in flower production, flower size, stem caliper at the graft union, winter survival, and early leaf drop, and increase susceptibility to cold injury have all been reported. Some infected cultivars may not show any symptoms at all.
- Purchase stock that is clean and/or certified as tested and free of all known viruses.
- Remove and destroy infected plants. However, the disease will not spread unless you propagate from or onto an infected bush.
- Heat-treat scion stock plants 4 weeks at 100°F before grafting.
Reference Golino, D.A., SIM, S.T., Cunningham, M., and Rowhani, A. 2011. Evidence of root graft transmission of two rose mosaic viruses, Prunus necrotic ringspot virus and Apple mosaic virus in rose rootstocks. Phytopathology 101:S62.