Verry beautifull.The fire weeding works great,never tryed but your garden looks verry good thanks to it.
I also got white dots dicoloration on my Prima paw paw and it growed giant leaves 40 cm big.I think it lacks somme nutrient because its just half a hear in the ground.
One grafted sunflower grew small leaves and then it dropped them ,looks dead and the otther sunflower kept its leaves but are small.
I think i lost 50 dollars tree with the sunflower that shed its leaves because it was posted for sale as a potted plant but i receives the tree in a bag with soil instead of a pot.
For such valuable trees id give them more time,maybe they recover.Have patience and dont hurry to replace those 2 trees.