Shot Hole Disease on Cherry: Coryneum Blight Management

Diagnosis Confirmed

Cherry leaves: brown spots → fall out → "shot hole" appearance. 20–30 holes/leaf. Rapid yellowing/defoliation (20–30% bare). = Coryneum Blight (Shot Hole), caused by Wilsonomyces carpophilus.

Disease Cycle

• Overwinters in infected buds/twigs.
• Spring rain splashes spores to new leaves.
• Wet weather favors spread.
• Fruit/flower infection also possible.

Management Program

1. Sanitation: Rake/destroy all fallen leaves, fruit, pruned wood.
2. Cultural: Prune for air flow; avoid overhead irrigation.
3. Fungicides (Start at Bud Break):
   • Copper (Bordeaux mix) — traditional, organic-approved.
   • Mancozeb — protectant, multi-site.
   • Chlorothalonil — effective, check label for stone fruit.
4. Timing: Apply at petal fall, shuck split, then 2–3× at 10–14 day intervals if wet.
5. Coverage: Thorough—entire canopy.

Key Point

This expert (Steve Young, Water Quality/Home Improvement) got peer confirmation. Shot hole is manageable with diligence—especially sanitation and early sprays.