Stem Gall

Forsythia viridissima occasionally develops galls or abnormal growths on stems, but specific information about causal agents and management is limited. The condition appears uncommon and of minor concern for ornamental growers in the PNW.

Galls are abnormal growths triggered by the pathogen and cannot be reversed once formed. Prune out galled tissue when practical, cutting well below the affected area. Avoid wounding plants during maintenance, as many gall-forming organisms enter through fresh injuries. For severe or recurring gall problems, consider whether the species is well-suited to the site conditions, as stressed plants tend to be more susceptible.