Troubleshooting
Royal medlar problems — and how to fix them
Royal medlar (Mespilus germanica 'Royal') is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Quince leaf blight (Diplocarpon mespili)
Causes irregular brown spots on leaves, leading to early defoliation. Remove fallen leaves; apply a preventive copper fungicide spray at bud burst in high-risk seasons or wetter locations.
Brown rot (Monilinia fructigena)
Fungal disease causing fruit to rot on or off the tree, often displaying white spore rings. Harvest promptly, remove all rotten or mummified fruits, and ensure good canopy airflow through light annual pruning.
Honey fungus (Armillaria spp.)
Can infect roots of stressed trees, causing sudden decline. Improve drainage; remove infected stumps nearby. No chemical cure; prevention through good soil health is essential.
Prevent royal medlar problems before they start
Most royal medlar issues are care-mismatch, not bad luck. Dial in the basics:
Royal medlar problems — FAQ
Why is my royal medlar quince leaf blight (diplocarpon mespili)?
Causes irregular brown spots on leaves, leading to early defoliation. Remove fallen leaves; apply a preventive copper fungicide spray at bud burst in high-risk seasons or wetter locations.
Why is my royal medlar brown rot (monilinia fructigena)?
Fungal disease causing fruit to rot on or off the tree, often displaying white spore rings. Harvest promptly, remove all rotten or mummified fruits, and ensure good canopy airflow through light annual pruning.
Why is my royal medlar honey fungus (armillaria spp.)?
Can infect roots of stressed trees, causing sudden decline. Improve drainage; remove infected stumps nearby. No chemical cure; prevention through good soil health is essential.