I am also trying to isolate Erwinia to taste some products to control this pathogen. Maybe you can use the crystal violet pectate medium, for the detection and isolation of Erwinia.
All the selective media for E. amylovora are, in fact, semi-selective. I would recommend to perform isolations simultaneously in different general/differential and/or semi-selective media. in particular, the most frequently used are King's B medium, Sucrose Nutrient Agar and CCT. You can find the recipes in the EPPO bulletin on E. amylovora: