Pathogenic fungi are fungi that cause disease in humans or other organisms. The study of pathogenic fungi is referred to as  medical mycology .. Although fungi are eukaryotic organisms, many pathogenic fungi are also microorganisms.Fungicides, such as ziram are used to protect plants against fungal infections.athogenic fungi are fungi that cause disease in humans or other organisms. The study of pathogenic fungi is referred to as  medical mycology .. Although fungi are eukaryotic organisms, many pathogenic fungi are also microorganisms.