Experts and BHG readers answer.
Are the corky swellings on the stems of my euonymus bush a disease or insect? What should I do for the plant?
Your euonymus bush has crown gall, a plant disease caused by a soil-inhabiting bacterium (Agrobacte-rium tumefaciens). Many species of plants are susceptible to the bacteria, which can remain in the soil for several years. The bacteria produce a substance that stimulates rapid cell growth in the plant, causing gall formation on the roots, crown, and sometimes branches. Galls are most often found at the soil line (crown) of the plant. You can't eliminate crown gall from your euonymus, but the plant may survive for many years. Prune out and destroy affected stems below the galls. Disinfect pruning shears after each cut. If you want to replace the shrub, replant with a resistant species. Among those resistant to crown gall are abelia, andromeda (Pieris), barberry (Berberis), deutzia, holly (Ilex), leucothoe, Oregon grapeholly (Mahonia aquifolium), serviceberry (Amelanchier), and sumac (Rhus).