Larryrolson

I don't think that's a disease problem at all. It looks to me like some kind of chlorosis caused by a nutrient deficiency. I would hit it with some all-purpose fertilizer with trace minerals or some rotted manure or compost and keep it watered well.

I'm not a big fan of maple trees. They have a shallow root system and suck the life out of everything near them. True very young trees need some shade. I wouldn't use a tree to give them that shade though it will stunt their growth if there is competition in anyway from them. Once they're halfway mature, and it looks like yours are in good shape, they do better in full sun.

I have done all mine from seed. I enjoy starting things from seed, and I have had some success and some failure. I am told that they turn out true to form from seed.

If you would like to try seed I would recommend looking up the website of the University of Kentucky. Several years ago they were very kind and send me an envelope full of seed from there select trees in the orchard.

These trees have a habit of suckering and I let them do it. Sometimes a good sucker will produce better than the mother tree

Good luck