Crown Gall (Agrobacterium tumefaciens)
Damage: Galls are somewhat round, rough, andvary
in size from
1/2 to several inches in diameter. The tissue inside these galls is usually
very firm, but later may show decay. Affected plants may be stunted,
produce small chlorotic leaves and maybecome more sensitive to environmental
stresses such as winter injury. Severely infected plants decline and
eventually die.
Cause: The crown gall bacterium enters plants
through wounds made by
transplanting, cultivation,grafting, and pruning. Other wounds caused by insects,
animals, or people can serve as avenues for infection to occur.
Prevention: To control crown gall, avoid wounding
susceptible plants at or near the
soil line. Prune infected branches and roots well back into healthy tissue.
To
prevent possible spread of the disase, sterilize pruning tools between cuts
with a 10% household bleach solution.Chemical treatment may be practical for
homeowners with valuable landscape plants. If plant is extremely infected
with galls,
removal may be necessary.