Great move in the article to show shifting distributions, not only a plot vs time of a shifting average etc. Possible confound not discussed: Have there been a

Great move in the article to show shifting distributions, not only a plot vs time of a shifting average etc. Possible confound not discussed: Have there been any changes in market or transportation or harvesting-technology or labor factors which would affect decisions about "harvest date" ? Were any new varieties systematically planted with/after X apparent breakpoint? Have direct effects, if any, of increasing CO2 been removed?