It's called fasciation - we've had a few threads about it over the last few years - the Search box will probably bring them up. Fascinating,fasciation.
Just rained 35mm in an hour according to my weather station. Bit wet.
There are two things they hate - roots being allowed to dry out and waterlogging. I suspect the latter in this case - I would lift the rootball from the pot and check the drainage holes aren't blocked. Some ericaceous composts are also a bit too 'heavy' for them and sometimes have clumps which hold too much water. Peat-based is better than loam-based ericaceous compost when it comes to blueberries. A third possibility is vine weevil grubs which gives you another good reason to check the roots.
Yes, the spines are much less pronounced when it grows larger and you can rub them off after picking. There is no limit to the number you can grow per plant but you must remove fruit when they are ready as the plant will stop producing if they start developing seeds inside (the fruit often turn slightly yellow when that happens so pick them when dark green and at any size from 15 to 25cm long.)
Yes, it won't help it fruit this year but it will thank you next year! Use ericaceous compost as they require acid soil. To do well they need to be in a pots of 50cm diameter or larger.
Try mixing one or two drops of washing-up liquid (or other very mild detergent) with water in a hand sprayer and spraying them. This breaks the surface tension of the water and effectively drowns them. On stronger plants you can use the spray attachment on a garden hose to blast them off. Encouraging wildlife such as ladybirds, hoverflies and small birds is the best thing to do in the longer term as these all eat aphids.
One possible cause is the roots drying out - they absolutely hate that.
I agree with Alan, they are lily aphids - here;'s one zoomed in:
1) Geum urbanum (wood avens) - another weed you don't want to let seed.
2) Tree seedling, probably birch.
3 & 4) Possibly one of the nightshades if not something you have sown.
Last edited: 09 June 2016 19:21:02