Why does Avery tell the Logan he can no longer shop in Vicksburg?

Mr. Jamison comes to the house. He tells Papa that one of the Wallaces has been threatening to put a stop to his black customers shopping in other stores. Mama is scared, but Papa asks her not to worry. Soon after, Papa says he has togo back to the railroad, even though he worries something will happen with the Walllaces when he is gone. Then T.J.'s father comes to the house. He tells the Logans he can no longer shop anywhere but at the Wallace store, because Granger and Wallace are charging him more money and calling in debts he can't pay. This is true for many other townspeople also. Papa is disappointed, but he understands. He tells hi