[trees]

Any tree (even a variety selected for consistent fall color) can show variation from year to year. That said... if there's not even a HINT of red in the leaves, then chances are it's not true to type.

I agree with treedoc's assessment that stress-related morphological changes would most likely be the biggest things to show up.

My experience is that a red maple cultivar selected for red will show red regardless of stress, it just may not be intense and may certainly have some yellows and oranges mixed in, but if you're not seeing red in the leaf, I'd put money on it not being true to type.

That's my 2 cents.

[johnkeegan]

...so back to my original question. Could this "Red Sunset," in fact, be a "Red Sunset" that just had a dismal fall color due to a combination of shade and transplant shock? For if shade would affect the fall color, wouldn't the shock of losing 80% of its roots also affect chlorophyll production (therefore sugars, therefore red color) because of a lack of availiable nutrients?

[trees]

I don't think so. 'Red Sunset' should have some red in it regardless of how dismal the color.

I've seen 'October Glory' trees go dormant in early september due to extreme transplant stress, but sure enough, they put on a sickly red for a few days before leaf drop.