Leaves are perfect...no obvious blight. Great looking bush..about 5 yrs old....but no fruit sets.
Not all black currant cultivars are self-fertile. That means a second bush might be required for cross-pollination to set fruit. If you know your cultivar, you can research whether that is the problem. This document may be helpful: https://www.crfg.org/pubs/ff/currants.html
Over the last two weeks my redcurrant bush started yellowing very rapidly. I started after I fed it sulphur of iron to lower the soils ph. Could be a coincidence? The ph isn’t very low anyway it seems. I added some soft fruit feed a few days ago but no improvement still.
Under or over watering is often the reason for yellow leaves so check that point. Also, since it started with the application of iron sulfate, I suspect that caused the yellowing. Possibly too much was used and it burned the plants.
Did you do a soil test before trying to lower the pH? That is always advisable before trying to change it.
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/raise-acid-level-soil.htm
To plant a black current bare root current what kind of potted soul should I buy
Choose a slightly acidic soil with a pH range of 5.5 to 7.0. These plants thrive in loamy or sandy soils. However, heavier soil can also result in a fairly good yield. Moisture retention is also important for the healthy growth of blackcurrants so add a layer of mulch on the soil.