How do I rewrite Solr search results to show related entity reference field? 1: I have two node types: "Plants", and "Pests". related using a field in the plants node type called "affecting_pests". 

How do I modify the solr Search result view; in the case of a Pests result, to display " name of pest==>affected plant " in the results title, and instead of link to pest page, redirect to the parent plant that the pest affects?
Assuming you are using the apachesolr module, implement hook_apachesolr_search_result_alter() in a custom module. The function you create will receive the $document object that you may modify. You will have to add logic in there to locate and load the appropriate related entity.