Bacterial Canker in Plums

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Bacterial Canker – dead buds in spring time

The Curse of Bacterial Canker

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Bacterial Canker – dead blossom in spring time

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Bacterial Canker – Gummosis

Bacterial Canker is evil. Walking the orchard this spring, to get a feel for how the trees have fared over the cold and wet (or warm and wet in this case) winter, I noticed that a few of the plum trees in the little orchard didn’t look great. On a few the blossom had withered and turned brown, on some the leaves had also turned brown or just remained as undeveloped buds which were dry to the touch. And on one tree in particular, we had the awful sight of gummosis, a potential sign of canker. With two of the trees we’ve had no fruit in the five years they’ve been in the ground, despite being on semi-dwarf rootstock, and the leaves did something similar last year. We’ve recently joined the RHS (Royal Horticultural Society) and they have a fantastic service whereby you can send samples in and they will carry out a pathogenic study for you, so you know what you’re dealing with.

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A common symptom of Bacterial Canker – early buds die, later foliage looks good with the possibility of ‘shotholes’. The leaves will drop early in the year.

Three days later and the three sample we sent off came back positive for Bacterial Canker – an opportunistic canker that infects wounds or prune cuts, remaining dormant over winter in the tree, to pop up in the spring. The infection causes leaves to drop early, allowing the infection to re-enter the tree through the leaf wound, and so infecting the tree for next year. The gummosis is a sign of a few tree problems, but the fact we also had dead leaf buds and blossom pointed to Bacterial Canker. In an older tree we could cut out dead wood and treat the tree to prolong its useful life, but as these trees are so young, and main branches were infected, I decided to pull them up and dispose of them. We’ve had problems in the orchard with cherries first, and now plums, and I suspect that the ground is having a part to play with it. Since that bad winter four years ago, where we were waterlogged for several months, the stone fruit has suffered. The majority of the cherries died in that winter, some survived but succumbed to a canker of sorts in the spring and summer, and now this warm wet winter seems to have done similar to the plums. The apple trees, touch fruit wood, are looking okay, so we’ll order more local varieties to replace the plums. I’ve also read that the rootstock M116 is a good choice for wetter sites than the MM106 we have the rest of the small orchard apples on, so I’ll try and track down somewhere that sells that rootstock.