I have English limited space for my vegetable garden and like to plant basically the same type of vegetables every year (tomatoes,, bell and hot peppers, okra, collard greens, kale, green beans cucumbers, scallions, squash and herbs). I find it difficult to rotate by beds each year. Is there anything I can do or add to my soil where I don't have to be concerned about fungus or diseases to my plant because I didn't follow the rotation rules?
If your bed is small, then you may not be able to rotate your crops. Select resistant varieties if possible. See the resistant varieties from Cornell http://vegetablemdonline.ppath.cornell.edu/Tables/TableList.htm
Take a look at some monitoring and management steps for preventing or reducing fungal and/or bacterial diseases http://extension.umd.edu/growit/fungal-and-bacterial-diseases-vegetables