
Dormant season and keep cuts light — it is a small, low-branching tree and hard reduction just buys weak watersprout regrowth. The species-specific work isn't pruning at all: leaf blotch (Guignardia aesculi) overwinters in the fallen leaves, so raking and hauling the litter every autumn buys more clean canopy next July than any cut will.
Nearly everything that looks fatal on a central Indiana buckeye isn't — blotch browning spreading from the interior outward, scorched leaf margins on the sun side, and bare branches by late August are annual events on a healthy tree. Genuine decline is branch-by-branch: twigs that fail to break bud at all the following May, thinning from the top down, and cankers or bleeding at the trunk.