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What are these brown spots on my quince tree’s leaves and fruit?
- Quince Leaf Blight is the fungus Diplocarpon mespili, which ruin your quince crops.
- It also hits medlars, pears, hawthorn, and pyracantha, but is almost never serious on those.
- It is closely related to Rose Black Spot, and is worst in a wet summer.
Leaf Blight causes lots of brown splotches on leaves with dark dots in the middle.
These start off reddish-brown then turn darker brown or black, typically joining up to make larger, irregular shaped patches on the leaves.
Once they spread enough, the rest of the leaf usually turns yellow and falls off.
The disease can spread to the fruit, which will show the same spotting and blotching, and often distort.
In severe cases, the soft wood at the tips of the shoots can be blighted and can die back.
Quince leaf blight treatment
As with most fungal infections, good hygiene works wonders. The disease is worst in areas where humidity is high and air movement low.
- Rake up and burn the leaves of infected trees when they fall.
- In Autumn, do the same with all leaves from the area where the tree is growing.
- Cut out infected shoots and burn those too.
- Remove dead twigs and branches anytime.
It may take a couple of years to eradicate, but the consistent burning of debris will kill overwintering spores.
Disease resistant Quince varieties
According to the RHS, the cultivars ‘Serbian Gold’ and ‘Aromatnaya’ were least affected by leaf blight in the wet Summer of 2023.
They were not disease free, but had little or no early leaf drop when more susceptible varieties were almost defoliated.
Spraying with Fungicide
There are no fungicides available for use in the UK on fruit trees intended for eating.
If you are not eating the fruit, you could spray your quince tree immediately and again in Spring just as the leaves open.
- Provanto ‘Fungus Fighter Concentrate’ and Toprose ‘Fungus Control & Protect’ contain tebuconazole & trifloxystrobin, Provanto ‘Fungus Fighter Concentrate’ only contains tebuconazole.
- Rose Clear Ultra contains both triticonazole against fungus and acetamiprid against insects. It is effective against Quince leaf blight, but overkill.