Saving a Black Chokeberry from Powdery Mildew and Treatment Damage

Rescuing Aronia After Powdery Mildew and Hydrogen Peroxide Burn

A black chokeberry (Aronia melanocarpa) in Northern New Jersey developed powdery mildew during a hot, humid spell. An organic fungicide was ordered, but before it arrived, a homemade hydrogen peroxide and baking soda spray was applied. The mildew disappeared, but many leaves turned black and began dying — classic chemical burn.

Immediate Steps

1. Remove damaged foliage: Pick off all blackened leaves, bag them, and discard — do not compost.
2. Deep water at the base: Soak the root zone thoroughly; avoid overhead watering to reduce humidity.
3. Apply a labeled fungicide: Use the organic product when it arrives, or switch to a chemical fungicide rated for powdery mildew on Aronia if needed.

Why This Happened

Chokeberries prefer consistently moist, well-drained soil. Heat stress weakens the plant, inviting mildew. The homemade spray, while sometimes effective, can scorch tender foliage, especially in sun or high temperatures.

Prevention

• Mulch to retain soil moisture.
• Water early in the day at soil level.
• Improve air circulation by thinning nearby growth.

With prompt care, the plant should recover and push new growth.