Quince Leaf Blight can be a nuisance on fruit trees such as medlar, pear and especially quince (hence the name). Usually the first evidence is of lots of small spots on the leaves. Quite quickly these turn from red to brown or black and they often join up to make larger, irregular shaped patches on the leaves which go yellow and drop early.
The disease can spread to the fruit which will show the same spotting and blotching and which may also distort as a result. In severe cases the soft wood at the tips of the shoots can be blighted and can die back.
As with nearly all fungal infections, good hygiene works wonders. Rake up and burn the leaves of infected trees when they fall. Do the same will all leaves from the area where the tree is growing in autumn. Cut out any infected shoots and burn those also (never compost infected matter). Spray your quince tree with a copper based fungicide immediately and then again in spring just as the leaves open.
It may take a couple of years to eradicate, but the burning of debris kills overwintering spores. The disease affects trees in areas where humidity is high and air movement low, so if your quince trees are prone to blight you may have to adopt the burn and spray regime for some time