
Spend on diagnosis before treatment. Drivers: an arborist site visit, and where a wilt is suspected, laboratory confirmation from a sample — the Purdue Plant and Pest Diagnostic Laboratory accepts homeowner samples and costs far less than treating blind (UNVERIFIED: current fee schedule). After that, cost scales with cause. Watering and mulch are nearly free. Deadwood pruning prices by crown size and access. A fungicide program prices per application per tree and recurs every year, which is the part to weigh carefully. An oak wilt response can include trenching to sever root grafts between trees, which is heavy equipment work. Be skeptical of any quote written before the cause has been named.
This is normally a tree trimming job, $250–$1,400, most near $550. A range, not a quote.