Genus Peronospora, commonly known as downy mildew, is a group of fungi that affect a variety of crops, including grapes, potatoes, and onions. While the name "Peronospora" is specific to this genus, there are several synonyms that refer to this same group of fungi. Some of the most common synonyms include Bremia, Phytophthora, and Plasmopara. These fungi are notorious for causing devastating damage to agricultural crops, particularly in humid and cool growing regions. Understanding the different names and classifications of these fungi can help farmers and scientists more readily identify and combat outbreaks of downy mildew in their crops.