Leaf Miners, Black Spot, and Fertilizer Strategy: Organic/Synthetic Rotation

Rachel: Leaf miner trails in rose leaves. Asks about Miracle-Gro vs. other fertilizers, Daconil for black spot, wet spring caused spots.

Fertilizer Philosophy: Alternate Organic/Synthetic

Spring: Synthetic granular (balanced rose food). Fall: Organic (Mills Magic, alfalfa meal, composted manure). Replenishes soil biology stolen by growth/bloom.

Supplement: Liquid (Miracle-Gro Bloom Booster or Miracle-Gro for Roses) every 2 weeks during bloom season—targets flower production.

Black Spot: Systemic + Contact Rotation

Immunox (myclobutanil) – contact, coats leaf. Ortho Disease Control (triforine) – systemic, inside-out. Use one in spring, switch mid-season. Prevents resistance. Spray proactively every 2–3 weeks.

Daconil (chlorothalonil) works but not systemic—strictly protectant. Good in rotation.

Leaf Miners

Most rose insecticides (spinosad, neem, pyrethroids) control miners. Read label for "leaf miner." One application usually clears season.

Cleanup

Remove spotted leaves. Sanitation + spray = control.