Rose Cane Galls: Bacterial Tumors on Stems

Quarter-Sized Growths on Rose Canes

Northern Michigan roses (near Alpena) have round, quarter-sized growths on stems. Green ones contain "seeds"; later, worms enter and eat them. Bug eggs or something else?

Diagnosis: Crown Gall (Cane Gall)

These are bacterial galls—tumors caused by soil bacteria (Agrobacterium tumefaciens) entering through wounds (thorn scratches, insect bites, pruning cuts).

Key Facts

• Bacteria live in soil; enter via wounds
• Once in one cane, can spread to others
• Won't kill the rose but may stunt growth
• "Seeds" = bacterial masses; "worms" = secondary insects

Management

Next spring, prune below galled areas. Dispose of galls by burning or trash (not compost). New growth will be clean.