Controlling Oyster Scale on Mature Maple Trees

A homeowner struggles with persistent oyster scale on mature maples despite two spray treatments. The infestation remains, prompting a search for more effective solutions.

Systemic Soil Treatment: A Better Approach

Sprays often fail to penetrate the protective waxy cover of scale insects. A systemic insecticide applied as a soil drench is far more effective. Bayer Advanced Tree and Shrub Insect Control (active ingredient: imidacloprid) is taken up by the roots and transported throughout the tree. When scale insects feed on sap, they ingest the toxin and die.

Application Timing and Method

• Apply as a drench around the root zone in early spring as buds begin to swell—this coincides with peak sap flow, ensuring rapid distribution.
• Follow label rates; typically one application provides season-long control.
• Water thoroughly after application to move the product into the root zone.

Additional Tips

Check local garden centers for availability. If the trees have already begun fall color change, delay treatment until spring. Avoid spraying the canopy—systemic treatment eliminates the need for foliar applications and reduces harm to beneficial insects.

Product details: Bayer Advanced 12-Month Tree & Shrub Insect Control.