Meyer Lemon Fruit Problems: Discoloration, Rot Smell, and Rust Mites

Symptoms on Young Meyer Lemon Tree

A two-year-old Meyer lemon has healthy dark green foliage but fruit develops brown discoloration as it ripens, smells like rot, yet looks normal inside. The skin texture is normal but the fruit is darkened—sometimes entirely, sometimes partially. Sooty mold was ruled out.

Possible Causes

• Black Spot (Fungal): Circular, dark, sunken spots on fruit. Treat with copper spray in early spring, repeat in 6 weeks.
• Boron Deficiency: Causes dry, brown flesh. Dissolve 1 tbsp borax in hot water, mix into 9L water, apply to soil once yearly.
• Citrus Rust Mites: Cause russeting and fruit damage; easy to control.

Recommended Organic Treatment

Use 100% pure neem oil (Dyna-Gro) as a fungicide, miticide, and insecticide. It absorbs into leaves, doesn't wash off, and protects new growth. Apply to new leaves as they emerge.

Additional Resource

Citrus pest and disease guide: The Garden Citrus Advice.