Problem with my Dogwood

Hi all,
Hopefully you can help identify if there is a problem with my Dogwood (Cornus Florida)
I only acquired it last autumn, i didn't get to see much leaf before they fell.
Growth this year seemed to be coming in OK but with vibrant light green coloured leaves.
Things over the past few weeks seem to have slowed and the majority of the leaves appear to be bleaching with interveinal chlorosis. I have it growing in a container, in a shelted area, quite shaded by an acer though it does get some early sun. Its potted up in Growmoor tree compost, I have fertilised it, half strength, (24-8-16) and Ph is floating about 7.5.
Could it possibly be Ca/Mg deficiency? Should I repot it in ericaceous compost? I'm hoping someone says they've got one and this is normal, sadly I feel its not. I appreciate that this dogwood may not really be suited to container growing but god loves a trier.
Thanks in advance,
Warm regards,
Alan.

 

It's not something I've grown but looking it up I see it likes acid to neutral soil.
7.5 is slightly alkaline and it does look like chlorosis .
I'd give it a watering with cheated iron and see what happens, if it is chlorotic then it should green up in a couple of weeks.

 

Have grown the ordinary dogwood and they seem bullet proof, but your young plants seem to be a flowering variety and the RHSs site suggest ph 7.0 or below.
Cornus florida | flowering dogwood Shrubs/RHS Gardening

Above 7.0 some nutrients become less available so that many be the cause and a dose of Epson salts, or iron as @pete suggests, may give some immediate help, though using ericaceous composts, or even good old garden soil ( if its 7.0 or below) would seem the better long term solution.
Chlorosis | Focus on Plant Problems | U of I Extension

 

Thank you. I do agree, ph is out. The feed its had containd Iron, however, if its locked out then....
I think I'll repot it in ericaceous.
Cheers guys.

 

Epsom salts are magnesium, so good for magnesium deficiency.
As I understand it Chlorosis is iron deficiency.

 

Are you saying you used a a liquid feed?
Any iron in a normal liquid feed is unlikely to be enough and as you say will be locked up by the ph of the soil.
If you add chelated iron or sequestered iron it overcomes the ph problem.

 

Often see Epson Salt recommended for chlorosis on Raspberries etc, though as you say it could be iron, this link explains how to determine which its the problem.
Chlorosis | Focus on Plant Problems | U of I Extension

Epson Salts has a lot use uses in the garden and found this site suggesting its a good slug deterrant, so will give it a try as it feeds the soil at the same time.
You can get big bags of it cheaply at the Pound shops, just the same as the more expesive fancy bath salts.
10 Reasons You Should Be Using Epsom Salt for Plants - Bob Vila

 

See, I knew I was going to learn something new by joining this site.
To save disturbing the tree I'll purchase some sequestered iron.

 

Interesting read @ricky101.
The new growth or the old growth is interesting.

I'm not so sure about the Epsom salts, I spent years spraying and watering my citrus plants with it before one watering of iron sorted out the problem for me.
Citrus are not considered ericaceous but they do seem to prefer things slightly on the acid side.