Help with currants and rose

I have two champagne currants and one Rosa rugosa.  For a few years the currants leaves have been yellowing.  I see no pests.  They get compost yearly.   It was just the one currants and I cut it back completely.   It is growing back but with same yellowed leaves and it's companion also had some yellowing.  Now I am noticing some of same with the rose.  For context,  this is a city garden,  zone 5b, initially straight city fill clay amended with horse manure (12 years ago).  Yearly leaf hummus and mushroom compost. They still fruit and flower. Thoughts?

It sounds like you are giving nutrition so I would rule that out.

Yellow leaves often mean over watering.  Have you had a wet spring?

Maybe it is fungal?

Anne Miller wrote:It sounds like you are giving nutrition so I would rule that out.

Yellow leaves often mean over watering.  Have you had a wet spring?

Maybe it is fungal?

We did have a wet spring and underneath is heavy clay... so maybe.

Heavy clay that stays wet is a classic setup for root issues. The yellowing on currants in those conditions often comes down to waterlogged roots more than nutrients — they really struggle to take up anything when the soil stays saturated. Worth digging down near the base after a wet period and seeing how long the water sits there. If it's more than a day or two, some grit worked in around the root zone or a simple French drain nearby might help more than more compost.

I'm thinking it is a nutrient deficiency. Am I imaginging that it is mainly older leaves that are affected? The RHS suggests either Nitrogen or Magnesium deficiency. I'm thinking Magnesium as the fruiting hasn't been affected.

magnesium deficiency image from RHS

Apparently too much Potassium can cause this, as it is taken up in preference. RHS suggest either Epsom salts on free draining soil, or Dolomite limestone on acidic soils. A foliar spray with Epsom salts may give a short term boost, and confirm the diagnosis.

Is your area wooded with a lot of wild goosberry (Ribes americanum)?