Plant Doctor Archive

Quince tree with leaf spot

I bought a Quince tree several months ago. It had a blight on its leaves at the garden centre and this has continued after planting. It seems to be a typical feature of these trees as I see the neighbour has one which also contains this blight. The blight is very damaging to new leaves and I find the tree is struggling to grow new foliage. I give it adequate water, so I am wondering what spray is best, if any, to rid the tree of this condition.

Quince trees (Cydonia oblonga) provide wonderful fragrant fruits used in cooking, but the trees themselves are also rather unique and attractive. Quinces are not quite as hardy as other members of the rose family, such as apples and pears, but can be grown in colder areas if protected from the severest frosts.

Quinces are very susceptible to leaf spot diseases if planted in warm humid areas and are especially vulnerable in places with humid summers. From your letter it does sound like this is your problem and there are a number of things you could try.

Firstly, I suggest you look at where your tree is growing. You need to make sure that there is plenty of air movement around the tree, and that it isn't being permanently shaded by other trees or buildings. When you water the tree, don't water the foliage, as this will only encourage fungi to grow. Remove any twigs or fallen leaves from around the base of the tree; this will reduce the amount of fungal spores in the area.

If the leaf spot disease is still a major problem, look for a fungicide spray for ornamentals at your local garden centre. Avoid spraying when the tree is in flower or near the time the fruit is ripe; you don't want to kill either the bees or the eaters of the fruit! Good luck.

Advice by Dr Dan Blanchon from Unitec's Diploma in Sustainable Horticulture and Bachelor of Resource Management.

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