Found it — and it's a textbook cold-then-warm herbicide injury.

Bird Point's early post pass (Corn Post 2025) went on May 5, a heavy mix of Capreno + Status + atrazine + Warrant. Look at the weather that week:

The field got sprayed right on a near-frost cold snap (lows of 37°F), then temperatures shot up 30°+ into the 80s within ten days. That's exactly the swing that makes corn over-metabolize the herbicide and injure itself — Capreno (a bleacher) and Status (a dicamba growth regulator) are both known to burn corn under a cold-then-rapid-warm pattern.

The clincher is the natural experiment across your fields. Seven corn fields got the same two-pass post program last year. What separated them was the date of that first pass:

Sprayed into the May 5–6 cold snap → all low:

Bird Point (Yarbrough) — May 5 → 179.6

Norwood — May 5 → 181.8

Ingalls — May 6 → 181.5

Waited to May 10 (cold snap passed, steady warm-up) → all fine:

Denton — 209.1 · Gaines — 210.9 · Jessup — 212.6 · Ransom — 210.2

Same recipe, same program, ~30 bu/ac gap — split cleanly by whether the post landed on the cold snap. Bird Point isn't uniquely damaged; it's the biggest field in the group that got sprayed too early, so the injury cost you the most bushels there.

A couple of things worth noting: Bird Point's May 5 pass covered 457 of its 720 acres, with the rest picked up May 22 in good weather — so if you walked it, the injury was probably patchy, worse on the acres hit May 5. And nothing else in the record points elsewhere: planting (Apr 17) was normal, the planter data looks clean, and it was actually your earliest-harvested corn, so weathering at harvest isn't it.

The takeaway for this year: hold the post pass when a cold snap is in the forecast, especially with a Capreno/Status mix. Want me to check Norwood and Ingalls in the same detail to confirm they saw the identical cold snap, or pull the applied-vs-target rates on that May 5 pass to rule out an over-application on top of the weather?