My poor Tulip Tree.!!

My beautiful Tulip Tree - Liriodendron tulipifera.. No flowers this year and I think it is having its leaves destroyed by leaf miner, do you all agree or do you think something else.. I am conscientious and scrupulous about picking the leaves up now and autumn when they all fall.. There is a Sycamore , my Bonsias and a cherry tree near by but none are affected.. All thoughts welcome please as it is gorgeous usually, except for this attack on the leaves...

​

 

It might also be the after effects of Scale Insects, Marley. My friend's Acer Brilliantissimum was badly attacked by them leaving the same markings on the leaves as your tree.

 

Oh dear... It doesn't look like leaf miner that is on other trees around the village I have to admit.. I am worried as the infected leaves are turning yellow and dropping quite quickly.. Maybe I will try and get my S in L to come and have a look then.. He is really busy this year though on a massive job that takes him and the team away all week, so not seen him at all.. Ho hum

 

Hmm thanks @pete it is mentioning the black/brown spots that appear first.. I will have a search on images in minute..

 

OK well the leaves just turn yellow all over I cannot see the darker veins they are all the same colour yellow when they turn.. Roots are not compacted and nothing deep rooted growing near except a couple of roses and some ferns which all look in excellent health and the Maple close by isn't affected though.. I shall have a closer look at the leaves when I get back in a while as have to dash now.. Thanks @pete

 

@pete Doh what am I thinking.!!!! I think you are spot on as I do have the darker veins and the mottling.. Thanks Pete you are a star.!