Roundup Near Newly Planted Live Oak: Unlikely Cause of Death

A homeowner sprayed Roundup around a newly planted 5-foot live oak to control weeds, avoiding foliage. The tree declined; they're told Roundup can't harm trees without foliar contact. They ask if it's possible.

Roundup (Glyphosate) Mechanics

Glyphosate only translocates in phloem of actively growing green tissue. It:

• Does not move through soil
• Does not absorb through bark (unless cambium exposed)
• Does not affect roots of non-treated plants
• Is routinely sprayed on tree trunks for vine control

Possible Explanations for Tree Decline

• Root exposure: A broken root at soil surface absorbed herbicide
• Sprayer contamination: Residual herbicide (broadleaf weed killer?) in tank
• Planting shock: Coincidental timing—new trees often defoliate from stress
• Watering issues: Too much or too little
• Planting depth: Root ball buried too deep

Diagnosis Steps

1. Scratch bark: green = alive
2. Check planting depth (flare visible?)
3. Review watering (1 inch weekly, not daily)
4. Confirm sprayer was clean

Generic Glyphosate

Products labeled "glyphosate" with same active % work identically to Roundup at lower cost.