Complex sentence: Another plant-associated type of mildew is downy mildew, caused by fungus-like organisms in the family "Peronosporaceae" ("Oomycota").
Split into simpler sentences: Another plant-associated type of mildew is downy mildew. Downy mildews are caused by fungus-like organisms in the family "Peronosporaceae" ("Oomycota").