Nectarine trouble

Dear all (especially @misterQ ) I need help!
I attach a picture of my nectarine bought as a "patio tree" in 2019(I think). In the past it hasn't fruited much at all, and suffered from lots of peach leaf curl. However, by constantly removing and binning dodgy leaves, and using a winter fungicide, it's now looking rather good, and this year set many fruit.
Unfortunately all but one got mouldy and had to be removed. The bits I could salvage tasted good, and I'm waiting for the last one to ripen.
Do you think it's just the density of foliage retaining too much humidity? A lot of them cracked as they grew, probably because of dry spring, but since then, it's rained a bit (Wales... )
Suggestions gratefully received.

 

It does have a lot of foliage, probably a dwarf mutant.
Usually splitting occurs when you get rain after a dry spell.

My apricots that were looking good are getting attacked before totally ripe by every pest known, birds slugs snails, I doubt I will see any after looking great just a week ago.

 

I was wondering whether to be be brutal and take out branches to increase air flow. It's basically a leaf umbrella at the moment.

 

I dont know I've never seen one with that amount of foliage.

 

It is extremely well foliated and I think opening it up to improve circulation would be a good idea.
I would like to know what you have been feeding it as many of my plants could well benefit from a similar diet.

 

Thanks @NigelJ ! Tbh I haven't fed it anything though it might have caught a bit of the horse manure that I threw on plants in the other border. The horse manure from my 2 field ornaments is pure manure, no straw, that has rotted down for a couple of years, so probably good stuff.
I hate to remove branches, but it is rather dense.

 

With that umbrella effect the roots are probably not receiving much water from rainfalls. Time to start pruning in Summer after fruiting. You also need to water at the base if you are not watering it.

 

Thanks @waterbut
You've all sadly confirmed what I thought I'd have to do - cut out some of the branches to improve air flow. With the amount of rain we regularly get here, I don't water it, but this spring was a bit different and probably caught me out.