Why was Dukakis so weak in the South?

[President Johnson]

I know the South already drifted away from the Democrats by 1988, but they still had a significant base of power in this part of the United States. Despite, Dukakis was extremly weak in South. In most states of the former confederacy, he got totally blown out by double digits (in some cases 20 points; states that were later won by Clinton). Only Missouri in the upper South was somewhat close. Why did Dukakis so poorly here or why was Poppy Bush so strong?

Bill Clinton by comparison did much better, but made it such a difference he was a Southerner himself? If so, this effect somewhat faded away quickly after his reelection 1996 because because Al Gore didn't benefit much from his heritage (though he did better in the South than Kerry in 2004). Lloyd Bentsen also didn't really help Dukakis in the South the way LBJ did for JFK.