Conversation so far:
What is the pine tar incident with George Brett?
In The Pine Tar incident with George Brett, Yankees manager cited a rule that any foreign substance on a bat could extend no further than 18 inches from the knob.
What happened after the Yankees manager Billy Martin cited a rule that any foreign substance on a bat could extend no further than 18 inches from the knob?
The umpires measured the amount of pine tar, a legal substance used by hitters to improve their grip, on George Brett's bat; the pine tar extended about 24 inches.

Question: What did he do?
Self-contained rewrite: What did the umpire do after Yankees manager Billy Martin cited to the umpires a rule, stating that any foreign substance on a bat could extend no further than 18 inches from the knob?