Growing Things: Some guesswork required for leaf drop, tomato 'catfacing'

Q: We have two 12-foot Ohio Buckeye trees beside our driveway, about six feet apart. Last year the leaves on one of them suddenly started turning bright red in August, and soon all were red, and then they fell off. The other tree stayed perfectly green, eventually turning yellow as normal.
It happened again this year, and I can’t see what the problem could be. Their conditions are identical, and if it’s some tiny pest at work it would surely spread to the other tree. Last year we too