Leaf spot (Diplocarpon)
Diplocarpon spp.
10 host plants · Fungal
Last updated
Red tip photinia (Photinia davidiana) develops leaf spots from Diplocarpon fungi, especially on young vulnerable growth. Plant in full sun, space for air circulation, remove fallen leaves, and avoid overhead irrigation or summer pruning. Apply fungicides to emerging shoots in early spring if disease recurs.
Leaf spot and blotch diseases are primarily cosmetic on established plants, though repeated years of heavy infection can weaken them. Rake up and remove fallen leaves to reduce the spore load going into the next season. Avoid overhead watering that splashes spores from the ground onto lower leaves. If the problem is severe, protective fungicide sprays during spring leaf emergence can help, but sanitation does more than chemistry for most leaf spots.
Quick Reference
Management
Spring (April-May) during new leaf growth; secondary vulnerability in fall (September-October) as temps cool. Young foliage most susceptible.
Spring and fall; cool wet conditions (50-65°F) with 8+ hours continuous leaf wetness. Rain-splash dispersal (Diplocarpon mespili on Crataegus and Cotoneaster).
Cultural Controls
- Plant in full sun.
- Space plantings and prune to improve air circulation.
- Clean up and destroy fallen leaves.
- Avoid overhead watering, or limit it to times when foliage can dry quickly.
- Avoid summer pruning, which promotes a flush of susceptible new growth.