Asparagus Diseases click on any image to view larger Purple spot lesions on asparagus spears Diseased asparagus crowns: Phytophthora on left, healthy at center, Fusarium crown rot on right. Stand decline and dead stems due to Fusarium crown rot Purple spot, caused by Stempylium vesicarium on asparagus stems Asparagus crown shown reddish brown discoloration and rot due to Fusarium Rust pustules (uredinia) on asparagus stem Overwintering stage (telia) of rust on asparagus stem Early season rust pustule (aecium) on asparagus stem