Diseased flowering plum tree

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Q: We have a tree or large shrub that has been growing in our front yard since 1990. It’s approximately three metres in height; the trunk itself is about one metre. It gets full sun, rain and wind. I was told that it is a flowering plum ‘Lizette’. The problem is that the leaves turn dark in colour in Spring and fall off. Eventually, the leaves grow back, but are small and there are no flowers. Apart from that, the tree/shrub appears to be healthy. It was pruned slightly a few years ago, but not lately. I have sprayed it with a copper spray mixture in the past, but that doesn’t appear to have helped. Could you offer some advice, please.

The problem could be a fungal disease called “Scab” (Venturea inaequalis), common on flowering crabapple and apple. The host plant is probably Malus ‘Liset’ which is supposed to be highly resistant according to the literature. Without a sample of the problem or proper identification of the host plant I will assume it is scab attacking a Liset flowering crabapple.

Remove and dispose of infected leaves in the garbage, not the compost. Thin branches within the plant canopy and any surrounding vegetation to increase air circulation. The only spray recommended is garden sulphur. Please read instructions as directed as suphur can potentially burn host plant on very hot days. Then pray for some good weather so the plant can regrow some new leaves. Maintain adequate watering, feeding, and mulching to ensure proper plant health.