Why Hydrogen Peroxide Isn't the Answer for Nectarine Gummosis

What Is Gummosis?

Gummosis (amber sap oozing) is a symptom, not a disease. In stone fruit, it's usually caused by the fungus Botryosphaeria dothidea (canker).

Why H₂O₂ Fails

• Hydrogen peroxide produces hydroxide radicals that damage fungal, bacterial, and plant cells.
• Cankers reside between bark and sapwood—topical application cannot reach them.
• 3% household H₂O₂ is likely too dilute for fungal control.

Proven Cultural Controls

1. Prune in spring when callus forms quickly; avoid fall pruning.
2. Cut to the swollen branch collar; no stubs or flush cuts.
3. Sanitation: remove and destroy (burn/bury) cankered limbs.
4. Fertilize per soil test; avoid late-summer nitrogen.
5. Control insect borers (peach tree borer).
6. Water during drought to reduce stress.

Bottom Line

Hydrogen peroxide is costly, ineffective, and potentially phytotoxic. Focus on the cultural practices above for long-term canker management.