Cause There are 9 different viruses reported on Forsythia. Tobacco ringspot virus (TobRV) and arabis mosaic virus appear to have been found in Washington. These are nematode-transmitted viruses.
Symptoms TobRV has been isolated from symptomless plants and from plants showing a yellow net symptom. Yellow net is where the veins on leaves become chlorotic (yellow) while the area between the veins remains green. Infected plants may also be stunted, show cane dieback during the summer and be more subject to winter injury.
Cultural control
- Select and plant only virus-tested (and found to be free of all known viruses) stock.
- Control nematode vectors.
- Remove and destroy affected plants.
Reference Kaminska, M. 1985. Some aspects of virus infection in Forsythia spp. in Virus Diseases of Ornamentals. Acta Horticulturae 164:263-271.