🐛✗ Tested and false“Blistered, puckered leaves on a blackcurrant or redcurrant bush need to be cut off to stop the damage spreading and protect the harvest”
The red and yellow blistering on currant leaves is caused by the currant blister aphid feeding at the shoot tips, and cropping usually remains unaffected by it. Management for all three currant aphid species is built around squashing small colonies by hand and encouraging predators like ladybirds and hoverflies, not stripping affected foliage. Once a leaf is already blistered, the aphids that caused it have typically moved to feed on newer growth nearby, so removing the older leaf mostly costs the bush healthy leaf area for no real gain.
What to do: Check new growth for small colonies through spring and squash or wipe them off by hand rather than cutting out already-blistered leaves, and leave the bush's natural predators to do the rest.
1 source
- RHS, Currant aphidsCropping usually remains unaffected by the currant blister aphid, and control relies on tolerating populations, monitoring, hand-squashing colonies and encouraging natural predators rather than removing damaged foliage.
“Currant bushes need spraying with an insecticide once aphid colonies are spotted, or the infestation will keep building”
No chemical control is recommended for any of the three currant aphid species; they're part of a garden's normal biodiversity that usually doesn't need eliminating. James Hutton Institute's own monitoring in northern Britain separately confirms these aphids aren't known to transmit any plant virus, which removes the disease-spread justification some gardeners reach for when deciding to spray. Spraying also works against the bush by killing off the ladybirds, hoverflies, parasitoid wasps and earwigs that are the natural predators keeping colonies in check.
What to do: Skip the spray, squash small colonies by hand where they're dense enough to worry about, and let predators established in the garden handle the rest.
2 sources
- RHS, Currant aphidsNo specific chemical control is recommended for currant aphids; management relies on tolerance, hand-squashing colonies and encouraging natural predators such as ladybirds, hoverflies, parasitoid wasps and earwigs.
- James Hutton Institute, fruitdisease.hutton.ac.uk, Ribes pestsSeveral aphid species colonise currants in northern Britain, and most damage leaves but are not known to transmit any viruses.
“Currant aphids feeding on the leaves will noticeably cut the size of the currant harvest”
This depends on which of the three currant aphid species is involved. Cropping usually remains unaffected by the currant blister aphid, and the permanent currant aphid does not normally affect the crop either, but the currant-sowthistle aphid is the one of the three which may affect cropping. A blanket claim that currant aphids reduce yield is true for one species and false for the other two on the same bush.
Our read Because the claim as usually repeated does not name a species, it reads as broader than the evidence supports for two of the three aphids involved, which is why this lands as disputed rather than a straight bust.
What to do: Identify which currant aphid is present before worrying about yield: distorted, yellow-mottled leaves point to the currant-sowthistle aphid, the one capable of affecting cropping, while blistered leaves or compressed shoot tips from the other two species are more likely to stay a cosmetic problem.
1 source
- RHS, Currant aphidsThe currant-sowthistle aphid is the only currant aphid which may affect cropping, while cropping usually remains unaffected by the currant blister aphid and the permanent currant aphid does not normally affect the crop.
