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Bald Cypress Knees Near Foundation: Root Barrier Installation

Root Biology

Cypress "knees" are pneumatophores—woody projections from roots that aid gas exchange in wet soils. They indicate active roots nearby. Cutting 10–15% of the root system (a 30–40° sector) on a healthy 50-ft tree usually causes only minor, temporary dieback on that side.

Root Barrier Best Practice

Use 24-inch deep high-density polyethylene (HDPE) barrier (e.g., DeepRoot, Root Solutions).
Install vertically along the foundation, not in a circle around the tree.
Trench with a narrow spade or trencher; cut roots cleanly with loppers or a saw.
Backfill with native soil; do not amend.

Herbicide on Cut Roots?

Applying glyphosate (Roundup) to the severed root ends away from the tree is safe if roots are fully severed and no vascular connection remains. Usually unnecessary if barrier is close to the foundation.

Free Expert Help

Contact your state forestry agency (e.g., NYSDEC) for a free on-site consultation by a service forester.

Trees: Bald Cypress Knees Threatening Foundation: Root Barriers or Removal?; Bald Cypress Knees in Yard: Cut Them, They'll Return If Soil Stays Wet; Do Stump Killers Kill the Entire Root System?; Bald Cypress Knees Invading Neighbor's Yard: Limited Options; Neighbor's Cypress Roots Damaging Driveway and Foundation; Coast Live Oak Near New Basement: Protect Critical Root Zone; Removing 50-Year-Old Italian Cypress: 24-Inch Grinding Is Fine; Bald Cypress Knees vs. Roots: Identification and Management; Bald Cypress Knees Threatening Foundations: Root Barrier Solutions in Texas; Cypress Knees and Foundation Risk Management

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