🐛✗ Tested and false“You can still eat plums or damsons affected by pocket plum if you cut away the deformed part”
Pocket plum doesn't leave a good portion to salvage: the whole fruit fails to swell or ripen properly, stays hollow with no stone ever forming, and turns papery as it ages. There's no unaffected core to trim down to, because the deformity runs through the entire fruit rather than sitting in one spot.
What to do: Pick and bin (don't compost) any fruit showing the flattened, hollow, stoneless shape as soon as you spot it, rather than trying to salvage part of it.
1 source
“Spraying a copper fungicide like Bordeaux mixture at bud burst prevents pocket plum”
RHS states plainly there are no fungicides available to amateur gardeners for control of pocket plum in the UK. Copper-based Bordeaux mixture, once recommended for this, has been withdrawn from amateur sale.
What to do: Rely on cultural control — remove and destroy infected pockets/pouches and prunings promptly, since there's no home spray available.
1 source
- RHS: Pocket plumThere are no fungicides available to amateur gardeners for the control of pocket plum
“Some plum or damson varieties are resistant to pocket plum, so you can plant your way out of the problem”
Neither RHS nor the Pacific Northwest Extension handbook names any plum, damson or ornamental Prunus variety as resistant or more susceptible to pocket plum. Both cover identification and cultural control, but neither has a cultivar-resistance section for this disease.
Our read This isn't a case of sources disagreeing, it's that the claim doesn't appear to have been tested or published by either institutional source we checked, so there's nothing to confirm or bust.
What to do: Don't choose a variety on resistance claims for this disease specifically; rely on removing infected material and accept that any Prunus tree can be affected in the right weather.
2 sources
“Removing infected fruit and branches promptly reduces how much pocket plum comes back next year”
The fungus survives winter on old diseased fruit still clinging to the tree or lying on the ground, and in bark and bud scales, ready to infect new growth the moment buds break the following spring. Taking that infected material away before it can shed spores cuts down the amount of fungus left to overwinter on the tree, though it won't stop reinfection completely if other Prunus trees are growing nearby.
Our read Neither source spells out a measured before-and-after reduction figure; the case rests on the overwintering mechanism both describe rather than a trial result.
What to do: Prune out infected twigs, witches' brooms and affected fruit before the white fungal bloom appears and releases spores, and put the removed material in the bin rather than the compost heap.
2 sources
“Pocket plum only takes hold after a cool, wet spring right when the buds break”
Infection of leaves, shoots and fruit happens specifically in wet, cool weather at bud break; a dry spring at that window gives the fungus far less opportunity to establish. RHS's own page doesn't discuss weather at all, so this comes from the Extension source rather than being confirmed twice over.
Our read RHS's page is silent on weather conditions, so this rests on the Pacific Northwest Extension source alone rather than being cross-confirmed by both.
What to do: Watch for the disease especially after a wet, cold spring, and check developing fruit through midsummer, since the deformed pockets don't become obvious until they reach full size in July and August.
In Scotland: A cool, wet spring right as buds break describes an ordinary Scottish spring more often than not, which is the exact window this disease needs.
1 source
