Rose of Sharon fungus. - Ask Extension
Trimming my Rose of Sharon (about 10' high) after a wicked winter - and noticed this mushroom-like fungus at the base. Can you please let me know ...
Knowledgebase
Rose of Sharon fungus. #925865
Asked March 11, 2026, 4:03 PM EDT
Trimming my Rose of Sharon (about 10' high) after a wicked winter - and noticed this mushroom-like fungus at the base. Can you please let me know how to treat this, if treatment is required. Many thanks.
Bucks County Pennsylvania
Expert Response
Hello and thank you for your question. The growths in your photos appear to be crown gall. Here is some information from Penn State Extension on the subject: Crown gall on Rose of Sharon, caused by the bacterium Agrobacterium tumefaciens, appears as rough, woody, tumor-like swellings (galls) on roots or stems, often near the soil line. These galls can grow up to 6 inches, disrupting nutrient flow, weakening the shrub and causing stunting or dieback. The bacteria enter through wounds caused by planting, grafting, pruning, or winter injury.
Unfortunately, there isn't any positive treatment for this bacterium; here is what Penn State Extension says you have to do next:
Management and Control
Jeanne
Unfortunately, there isn't any positive treatment for this bacterium; here is what Penn State Extension says you have to do next:
Management and Control
- Remove and Destroy: Severely affected plants should be removed, including the root system and surrounding soil, and disposed of in the trash, not composted.
- Sanitation: Sterilize tools (shears, saws) with rubbing alcohol, 10% bleach solution, or disinfectant between cuts to prevent spreading the bacteria.
- Prevention: Purchase only certified, disease-free nursery stock.
- Replanting: Avoid planting susceptible species (roses, grapes, fruit trees) in the same spot for at least 3 years, as the bacteria can survive in the soil.
Jeanne
