Mexican Fence Post Spots: Sunburn vs. Insect Damage

Two Diagnoses by Spot Size

Large Spots = Sunburn

• Cacti thicken south-side skin for UV protection.
• Nurseries rarely mark orientation.
• Planted rotated = burned tender tissue.
• Permanent cosmetic damage only.

Small Spots = Scale Insects

• Tiny, numerous = cochineal or similar scale.
• Nearly impossible to eradicate chemically.
• Manual removal (squishing) only effective method.

Verification

Email photo to greg8365@hotmail.com for confirmation.

Prevention

Always mark south side at nursery; plant same orientation.