P. brassicae may refer to:

• Phyllosticta brassicae, a fungal pathogen
• Phytometra brassicae, a moth that is very destructive to plants
• Phytophthora brassicae, a water mould
• Pieris brassicae, a pest butterfly
• Plasmodiophora brassicae, a plant pathogen
• Pyrenopeziza brassicae, a plant pathogen

• 20 Greatest Hits (Kenny Rogers album)
• 20 Greatest Hits (Simon & Garfunkel album)
• 20-h
• 20 High St, Nantwich
• 20 High Street, Nantwich
• 20 Hours in America, Part I
• 20 Hours in America Part I and Part II
• 20 Hours in America (West Wing episode)
• 20 Hoxton Square
• 20-hydroxyecdysone
• 20 in 10
• $20 in 20 seconds
• 20 Inolvidables (Los Bukis and Los Temerarios album)
• 20 ITK 35
• 20 ITK 38K
• 20 ITK 40 VKT
• 20 Jahre - Live in Frankfurt
• 20 June 2009 Kirkuk bombing
• 20 June 2010 Baghdad bombings
• 20 kilometer race walk
• 20 kilometer walk
• 20 kilometre race walk
• 20 kilometres
• 20 kilometres (disambiguation)
• 20 kilometres race walk