Most galls do not adversely affect plant health. Therefore, management is generally not suggested to protect plant vitality. Chemical applications are an option, but are often ineffective since the precise timing of sprays is critical. To be effective, sprays must be timed to coincide with initial insect/mite activity before gall formation begins. Once galls start to form, they conceal the causal organism and it is too late for treatment. For insects/mites that overwinter on the host plant, horticultural oil applications can be made before insect/mite activity begins in the spring.
Ray Ridlen is an agriculture/horticulture educator for the Oklahoma County Extension Service. His column addresses frequently asked horticulture questions. For more information, call 713-1125.