After nearly six months of testimony, hearings in California on alleged unfair labor practices at America's biggest peach grower finally closed on Thursday—and sparks flew all the way to the end of the hearing and beyond.

As CNBC first reported in 2013, Gerawan Farming was surprised when the United Farm Workers (UFW) union resurfaced in 2012—after a 20-year absence—to demand negotiations on a labor contract for more than 3,000 farm workers at one of the world's largest fruit growers.