Mold resistance has more to do with bud structure, not root structure.

Looks like leaf miner damage. https://en.wikipedia.org/wiki/Leaf_miner

Trace element deficiencies like iron would yellow new growth up top. This damage is not nutritional. It’s from some pest sucking on your leaves.

Grafting perennials makes sense. Grafting annuals makes far less sense. Time is money.