Symptom Identification and Control Methods of Hydrangea Ringspot Virus

[Distribution and Damage] Hydrangea (Hydrangea macrophylla), also known as bigleaf hydrangea, is a deciduous shrub planted throughout China. Many viruses infect it, with ringspot being the most common.

It is generally latent; severely affected plants are stunted with few or no flowers.

[Symptoms] Leaves are crinkled, and stems sometimes show necrotic spots. In inoculated diseased plants, old leaves develop chlorotic spots, brown ringspots, or oak-leaf patterns.

[Pathogen] The virus HyRSV, also belonging to the potato virus Y group. Particles are filamentous, measuring 470-650nm x 13nm. Thermal inactivation point 70-75 degrees C. Dilution endpoint 10-5. Longevity in vitro 21-35 days (at room temperature). This virus has distant serological relationships with potato virus X, cactus virus X, white clover mosaic virus, and others.

[Disease Development] Hydrangea is the only natural host. Artificial inoculation can infect more than 20 plant species. Globe amaranth, Chenopodium quinoa, and cucumber can serve as indicator hosts. Primrose can serve as a propagation host. Infected perennial roots are the main source of infection. Cuttings or divisions can transmit the disease, and grafting or tools can also carry the disease.

[Control Measures] Pay attention to tool disinfection. Select disease-free mother plants for propagation, or carry out heat treatment at 38 degrees C for 4 weeks. Breed disease-resistant varieties.