A little help from my friend

The area I have been calling a food forest want to be has changed. We removed a large old apricot tree. I'm not going to lie it made me quite sad to remove it, but it was down to one living branch, and that didn't look great. Out it went. It's surprising how much it opened that space. I planted a bare root apricot, an Asian pear and a pear. The trees are doing well, except the apricot is growing pretty low, and the little existing branches are dead. It's very strange. The growth is above the graft, so I'm just going to let it do it's thing.
I decided to plant blueberries in pots and put them between the apricot trees. There are also two pots with sweet potatoes. The mature tree should give some much needed afternoon shade. Being a a tight budget I used the black nursery pots. I always worry about planting in them because I worry about the soil super heating the roots. I lined the pot with cardboard. I was thinking it will hopefully keep the soil a little cooler. I have been thinking maybe I should paint the outside of the pot white, or cover them in burlap, and I still might in the future, but for now mother nature is taking care of it for me. I have a volunteer growing, I believe it's a pumpkin. Boy is it growing well. I was going to put watermelon there, but I decided to just enjoy the free no work pumpkin.  It's started to grow around the pots. Problem solved the large leaves of the pumpkin will shade the black pots.  I just love it when nature helps me out. Not only will we enjoy the pumpkin, but it will provide shade for the pots, ground cover for soil health, and maybe a little weed suppression. This beautiful pumpkin plant is definitely my friend.

A volunteer pumpkin, so cool!  I'm beginning to really focus my attention on what is volunteering and where.  Tomatoes (many) every year.  Potatoes are growing, perhaps from ones I missed last year.  Lamb's quarters.
I figure if they want to grow, that's what I'll eat.

I’ve had good luck keeping potted plants cooler by slipping the pots inside slightly bigger ones and stuffing the gap with leaves or straw, kind of like a quick DIY cooler. The soil stays way steadier on hot days. Your trick with cardboard works too, but this gave me longer relief in full sun. Volunteer pumpkins are gold for shade, I let them roam wherever they want.

Hmm... A thought: did you plant the apricot close to where the old one was? Prunus fruits put out autotoxicity chemicals in the soil, so if it's too close to the old tree's site, that could possibly explain why it's not doing super well... If it started declining only after planting, that is?

I didn't plant it in the same spot, but pretty close. The tree looks dead now. Maybe that's why?   The other 2 trees I planted in the area the same way look great. I do have a volunteer, maybe a group of volunteers that may be apricot. They are  in the middle of the pumpkin jungle, so I haven't closely inspected it/them. If they are, I may try to move them this winter. Or I have to move the pear tree, because they are way to close to coexist.
Thanks for both of your helpful comments.