Plant Doctor Archive

Fungus on tree

I HAVE a nice ornamental spring-flowering tree which I think may be some sort of plum, although it doesn't bear fruit. It has pink flowers and reddish coloured leaves. About half a metre up from the base it had a fungus growing from the trunk, like a little shelf sticking out. I removed the fungus but the next year it did the same thing. I now notice there are two dead branches on that side of the tree. Should I cut them off, even though it will make the tree lopsided? Will the tree recover and can I do anything to stop the fungus returning?

YOUR tree is almost certainly a species of Prunus which includes plums, apricots and cherries of which there are several ornamental flowering varieties. It sounds like it is infected with a fungal disease that has spread into the trunk and branches. The shelf-like fungus you removed is the fruiting body of the fungus (like a mushroom) and the rest of the fungus will be growing inside the woody parts of the tree. The dead branches are a sign the tree is gradually succumbing to the disease and I'm afraid there's very little you can do to save it once the disease has reached this stage.

However, it may hang on for years yet, so to try to keep it going you could remove the dead wood by cutting back to healthy tissue, which should be fresh and white looking - stained dark or brown is a sign of the disease. Spray the tree thoroughly in winter a couple of times with a copper-based fungicide and in summer try to provide ideal growing conditions by watering and fertilising if necessary and controlling any other pests and diseases that may also take advantage of its weakened state.

Otherwise, to save yourself trouble, cut the tree right out and replace it with another spring flowering tree unrelated to Prunus, like the Judas tree, Cercis siliquastrum.

Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.