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Shothole
Abby2
Posts: 101
Just wondering if anyone can advise me. I have 3 flowering cherry trees, a Kanzan and two Amanogawa. All appear to have signs of shothole on the leaves although I can't yet see any sunken patches, oozing or canker on the branches.
After doing some googling, I'm still not clear if this will eventually kill my trees so am unsure of what I can do to treat them at this stage? Would be such a shame to lose all three 
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I had it confirmed by a chap at the garden centre that the trees do indeed have shothole. What would be really useful at this stage is to know whether anyone has successful eradicated this disease using a winter wash or fungal treatment? This is what was advised but both treatments are expensive and I'd rather invest in new trees and get planting them now if the treatment will be pointless!
Many thanks for any advice you could offer...
Hi Abby,
The pathogen causing canker and shothole in Prunus is bacterial - Pseudomonas.
The bacteria live on the surface of the leaves and during wet conditions in spring or early summer they can gain entry to the leaf via the stomata, causing the development of infection and resulting in patches of dead tissue, which fall out to leave the shothole symptoms.
Stem cankers only occur when the bacteria gain entry to the stem via leaf scars after leaf-drop or via wounds e.g. from pruning or damage.
Pruning of Prunus should only be carried out between July and August, when plant tissues are at their most resistant to infection.
If you notice any cankers, these should be pruned out at this time, well back into healthy tissue. It may be advisable to paint the pruning cuts with wound paint to prevent re-infection.
Pruning equipment should be sterilised with Jeyes Fluid or a similar disinfectant and all the prunings should be burnt or included with general waste for landfill.
I have 3 cherry trees in my garden all affected by bacterial canker. So far, some smaller branches have been lost to the disease but the trees themselves seem to be fine at the moment.
Brilliant thanks - thats all very helpful. I will try the Bordeaux mixture on the young tree as suggested and be vigilant about cankers forming on the larger ones. I have only ever pruned in August so hopefully will have minimised the risk a little. Good tip about sterilising equipment - I will do that from now on!
Bordeaux mixture has been withdrawn from the market, due to the copper toxicity in the soil causing harm to earthworms and other beneficial organisms.